Charles Otto Dhonau

Anatomy

The word anatomy is derived from two Greek words, meaning, to cut apart, which literally means dissection.

Anatomy is used to indicate the study of the physical structure of organized bodies.

Anatomy is the science of organization or the science of organic structure.

Human anatomy is divided into two great divisions, known as (a) general or descriptive anatomy and (b) surgical or regional anatomy.

Descriptive anatomy deals with the separate parts of the human body.

Histology is that part of descriptive anatomy where the separate parts of the human body are studied by means of the microscope.

Osteology is that part of descriptive anatomy describing the number, form, structure and uses of bone.

Myology is that part of descriptive anatomy which treats of muscles.

Neurology is that part of descriptive anatomy which treats of nerves.

Syndesmology is that part of descriptive anatomy which treats of ligaments.

Angiology is that part of descriptive anatomy which treats of the blood-vessels and lymphatics.

Surgical or regional anatomy describes the relation which certain parts,—muscles, nerves, arteries, etc.,—bear to each other.

CHAPTER IV. HISTOLOGY.

Definition.

—Histology is that part of descriptive anatomy which treats of the intimate structure of the tissues as seen under the microscope.

Histology as taught in most professional schools constitutes a one year's course, but for the embalmer this is not entirely necessary and with the short term of schooling now existing it is quite impossible, but certain of the fundamental principles of histology are important. For this reason a few of the more important tissues have been discussed, not, however, in great detail, but only superficially, merely to have the embalmer acquainted with them.

A Cell.

—A cell is defined as a nucleated mass of protoplasm endowed with the attributes of life.

Protoplasm is the name applied to the semi-fluid, granular substance contained within the cell.

The simplest forms of animal life are organisms consisting of only one cell which are called protozoa.

Cells having similar shape and similar functions are grouped to form tissues.

Tissues are grouped together to form organs.

Every cell consists of a cell body and a nucleus. The cell body consists of a substance known as protoplasm. The nucleus is the essential part of a typical cell and is the controlling center of its activity.

Fig. 1—A, A vertical section of the cuticle; B, the lateral view of the cells; C, the flat side of scales like (d) magnified 250 diameters.

Cells divide or reproduce themselves by means of direct or indirect division. In direct division the nucleus and the cell wall simply divide into two equal divisions and results in the formation of two new cells. In indirect division the process is much more complicated, and several stages must be passed through before there is a complete division.

The process of fertilization consists in the conjugation of two sexual cells. The male sexual cell is called the spermatazoon, and the female sexual cell is called the ovum.

The nucleus of the ovum in its earlier development stages is known as the germinal vessicle.

In the living organism many cells are destroyed during the various physiologic processes and are replaced by new ones. When a cell dies, changes take place in the nucleus which result in its gradual disappearance. This process is known as chromatolysis.

Tissues.

—A tissue is an aggregate of cells all having a common function.

Those important tissues with which the embalmer should be more or less acquainted are the following:

Skin, nails, hair, superficial fascia, deep fascia, lymphatics, glands, cartilage, bone, teeth, nerves, muscles, tendons, aponeuroses, ligaments, fat, mucous membranes, serous membranes, synovial membranes, arteries, veins and blood.

The Skin.

—The skin or integument (intego, to cover) is the outside covering of the human body. It is the first tissue that is cut when operating upon the body.

Fig. 2—A cross section of the skin. (Gray)

The skin is the seat of the organs of touch. The multitudes of sensory nerve endings convey the sensations of temperature, pressure and pain to the brain, thus informing the brain at all times, to keep the body from harm, and in a strong and healthful condition.

The skin is also the regulator of the body temperature, for connected with the skin are sweat glands, and sebaceous glands, each having important excretory functions.

The skin is also a protective coat, very elastic, and varies greatly in thickness. It is thinnest in the eyelids and thickest over the back of the neck, back of the shoulders, palms of the hands and the soles of the feet.

The color of the skin depends upon two things, first, on the pigment, which is found, one of the discriminating points between the races, named by the color of the skin as white, black, yellow, etc.; second, the color depends upon the amount of blood in circulation, the deepest hue being in the parts exposed to the air, light and the varied temperatures. Besides these the color of the skin varies with age, pinkest in the infant and becoming yellow with old age. It varies with exposure and with climate, the people living in the north having a much different complexion than those living in the south under the tropical sun. The color of the skin also varies with certain diseases, being extremely pale in anaemia, brown in Addison's disease, and yellow in jaundice.

The skin can be said to be moveable, although in places it is attached firmly to the underlying structures, especially on the scalp, the soles of the feet, and the palms of the hands.

Upon close examination the skin discloses a multitude of openings, creases, furrows, depressions, folds and hairs.

A dimple is a permanent pit or depression due to the adhesion of the surface to parts beneath.

Structure.—The skin consists of two intimately connected structures, the one is the true skin, corium, or dermis and is the deepest layer of the skin; and the other is the false skin, cuticle, or epidermis, and is the outermost layer of the skin.

The true skin, is composed mostly of connective tissues and elastic fibers. It is the real seat of the sense of touch, for it is here that the sensory nerves have their termination. In this layer we also have the termination of the minute capillaries of the skin.

The false skin, contains no blood vessels or nerves, and being without these it is practically dead tissue, and to illustrate this fact one can take a needle and run it through this outside layer without the least pain or the drawing of blood.

The false skin is the part which slips off in case of skin slip. In as much as the minute capillaries end at the termination of the true skin, when putrefaction and fermentation begin there is an oozing of water from the capillaries and the surrounding tissues, between the two layers of skin, causing a blister to form, and known as skin slip.

At the lowest part of the false skin is a layer of germinal cells, from which all the other cells are derived, and becoming more flattened and horny as they are pushed farther away from the blood supply; and also a layer of pigment cells, which give the discriminating color to the skin.

In the skin are seen numerous sebaceous and sweat glands.

The sweat glands are the organs by which a large portion of the aqueous and gaseous materials are excreted by the skin. Sweat glands are found in almost every portion of the skin, and are situated in small pits below the surface of the skin, surrounded by a quantity of adipose tissue or fat. They are small, round, reddish bodies, consisting of a single tubule, convoluted in form, which extends up through the skin and opens on the surface. The size of these glands, of course, vary, being especially large in those regions where the flow of perspiration is copious as in the axilla.

The sebaceous glands are small, sacculated, glandular organs, lodged in the substance of the skin. They are found in most parts of the skin and are usually connected with the hair follicles. Each gland consists of a single duct, more or less capacious, which terminates in a cluster of small secreting pouches or saccules. These glands secrete an oily fluid, which keeps the skin soft and also oils the shaft of the hair.

The Nails.

—The nails are a peculiar modification of the epidermis and have the same cellular structure as that of the epidermis. The nails are found on the dorsal surface of the fingers and toes and act as a protection, and enable one to pick up small objects, or to grasp more firmly any object. Were it not for the nails it would be impossible for one to pick up a needle from off the floor.

Each nail is convex on its outer surface, and its chief mass which is called the body lies upon the nail bed, or true skin; the free end projects out over the surface of the finger, and is that part which is not attached below, and since it is the continuation of the epidermis, it likewise will have no nerve or blood supply and therefore can be trimmed without pain to the individual.

The root is implanted in a groove in the skin and is composed of cells which have not become horny. The root is white in color and is the little half moon which you can see next to the skin.

The matrix is that part of the true skin beneath the body and the root of the nail, and is so called, because, it is that part from which the nail is produced and so long as the matrix at the root of the nail is uninjured, the nail will be reproduced after an accident.

After death the nail turns black, due to the infiltration of blood into the matrix.

Treatment by the Embalmer.—The blackened condition of the nail due to the infiltration of blood into the matrix can in many cases be overcome by carefully rubbing the nail at the time the body is being injected. After the discoloration is removed the fingers should be kept elevated so that the blood will not settle there again.

The Hair.

—The hair, like the nails, is a peculiar modification of the epidermis and consists of practically the same cellular structure as the epidermis. Hair is found on nearly every part of the body excepting the palms of the hands and the soles of the feet, the borders of the lips, etc. It varies much in length, thickness and in the different races of mankind. In the eyelids it is short, on the scalp it is of considerable length. In other parts as the eye-lashes, the hair of the pubis region, the whiskers and beard the thickness is remarkable.

A hair consists of the root and the shaft. The root of the hair or that part implanted in the skin presents at its extremity a bulbous enlargement, called the hair bulb. Into this bulb we find the small arterial capillary circulating and at its termination the beginning of the venous capillary. In this way the hair is nourished in life. We also find a small nerve going to the hair bulb. The shaft is the remaining part or that part coming out from the skin.

The hair grows from its roots and as it grows it pushes itself out from the skin and owes its growth to the small capillary circulation, carrying pure arterial blood to each and every hair, and for this reason you can understand for yourself the erroneous idea of what is termed the “post-mortem growth of hair.” Only a few weeks ago one of the students declared that he had actually seen a subject shaved and the body at the time of the funeral was placed in a vault to await the arrival of a close relative who had to come from Europe.

Three weeks later the student, together with the undertaker and relatives, went to the vault to view the remains. The body was in a perfect state of preservation, only for a large growth of beard as the student supposed. This student had observed rightly, but he did not go far enough. He did not think of how the hair actually got its nourishment. The hair owes its life to the circulation of the blood, just as much as the heart or any other organ does, and will die and cease to grow just as soon as the body dies and the circulation is cut off. What this student saw was only an apparent growth, for after the body dies the tissues begin to shrink, squeezing the blood and fluid substances out of them, thus giving the hair cylinder a more projected appearance.

The student was very much surprised at his mistake, but after the explanation he saw that the hair owed its life to the circulation and that when this circulation was cut off, the hair must cease to grow.

The chief function of hair is that of protection from heat or cold and to help shield the brain from the effect of a blow upon the head.

The hair, next to the teeth and bones, is the least destructible part of the body.

The Fascia.

—The fascia (fascia, a bandage) is areolar or aponeurotic tissue of variable thickness and strength found in all regions of the body and invests or surrounds the softer and more delicate organs. From its situation in the body the fascia is divided into two groups, superficial and deep.

Superficial fascia is found immediately beneath the skin over almost the entire surface of the body. It connects the skin with the deep fascia and consists of areolar tissue.

The superficial fascia varies in thickness in different parts of the body and some places, especially in the groin is capable of being subdivided into several different layers. The first layer of the superficial fascia, which is just beneath the skin, usually contains a great amount of fat or adipose tissue. This, in most text books, has been termed the subcutaneous tissue. The second layer is comparatively devoid of adipose or fatty tissue and in this we find the trunks of the subcutaneous vessels and nerves, as for example, the radial and ulnar veins in the arms and the saphenous vein in the leg.

The superficial fascia facilitates the movement of the skin, serves as a soft medium for the passage of the vessels and nerves to the skin and retains the warmth of the body, since the fat contained in its meshes is a had conductor of heat.

Deep fascia or aponeurotic fascia is a dense inelastic, unyielding fibrous membrane, forming a sheath for the muscles and affording them broad surfaces for attachment. On removal of the superficial fascia, the deep fascia is usually exposed and can be seen as a dense, tough membrane, which not only binds down the muscles to each region, but gives to each a separate sheath as well as to the blood vessels and nerves.

Thus, on going down into the arm between the biceps and triceps muscles to raise the brachial artery, you would first cut through the skin, then the subcutaneous tissue, the superficial fascia and then you would come to a membrane investing the artery, vein and nerve. This membrane is the part of the deep fascia which covers the vessels, making a distinct sheath for them and you must go through this sheath before you can hope to raise the artery.

Fig. 3—Lymphatics of the head and neck. B, the thoracic duct.

The Lymphatics.

—The lymphatics occur in all parts of the body, and in many respects resemble the veins, one of the most striking similarities being that the lymphatics contain valves just the same as the venous system. The lymphatic capillaries are arranged in the form of a net work and resemble closely in structure the blood capillaries. These capillaries then unite to form the lymph vessels and these then convey the lymph to the subclavian veins. The lymph is a colorless fluid and contains numerous blood corpuscles known as lymphocytes. But in those lymphatic vessels, which have their origin in the walls of the small intestines, the lymph, especially during digestion, contains a great amount of fat, so that it has a milky appearance, and for this reason the lymphatics of this region, have been termed lacteals. There are two main lymphatic trunks, the one on the left side is called the thoracic duct. This duct extends from the lower border of the second lumbar vertebra, through the entire length of the thorax, and opens into the left subclavian vein, close to the point where it is joined to the left internal jugular. It receives the lymph from the lower limbs, the pelvic walls and viscera, the abdominal walls and viscera; the lower part of the right half and the whole of the left half of the thoracic viscera, the left side of the neck and head and the left arm.

Fig. 4—Lymphatics of the leg.

The other duct is called the right lymphatic duct and receives lymph from the upper part of the right side of the thoracic wall, part of the right side of the diaphragm and the right lobe of the liver, the whole of the right arm and neck and right side of the head. This trunk is very short and empties its supply of lymph into the right subclavian vein.

Receptaculum chyli is the expanded portion of the thoracic duct just at its beginning. Its function is to receive the lacteals which come from the villi of the intestines.

Lymph glands are the enlargements of the lymph vessels. They occur frequently in the lymphatic system, being most numerous in the axillary space, the cervical region (in the neck) and in Scarpa's triangle.

The lymphatic system aids greatly in warding off such diseases as blood poisoning, anthrax, etc.

The lacteals are the lymphatics which carry the chyme from the villi of the intestines and deposit it in the receptaculum chyli.

Glands.

—The glands of the human body are divided into three classes called tubular, alveolar and tubulo-alveolar glands.

Tubular Glands.—In these, the secreting portion consists of a long or short tubule, which may be relatively straight or variously twisted, one end of which ends blindly, while the other end opens on the free surface or into a duct.

Tubular glands may be simple, or having only a single tubule; they may be simple branched, having more than one tubule; or they may be compound branched, thus resembling the branching of a tree.

Some tubular glands would be the liver, kidneys, testes, lachrymal glands, serous glands of the mucous membranes, fundus glands of the stomach, uterine glands, the majority of the pyloric glands and the majority of the sweat glands.

Alveolar Glands.—In these, the secreting compartments have the form of variously shaped vesicles or saccules, known as alveoli which open on the free surface or into a duct.

Alveolar glands may be either simple, simple branched, or compound branched.

Some alveolar glands would be the sebaceous glands, pancreas, mammary gland, ovary and thyroid.

Tubulo-alveolar Glands.—In these, there is a combination of the tubular and the alveolar type. They may also be simple, simple branched or compound branched.

Some of this type would be certain of the pyloric glands, certain of the sweat glands, some mucous glands, the prostate and the lungs.

The most important glands will be discussed under the tissue or the organ in which they are situated.

Cartilage.

—Cartilage is a transition stage between connective tissue and bone; when it is boiled it yields condrin. It is found in various parts of the body, in the adults being found chiefly in the joints, in the sides of the thorax, and in various tubes which are not kept permanently open, such as the air passages, nostrils, ears, etc. In the foetus, the greater part of the framework is cartilaginous and as the foetus matures this cartilage is finally replaced by bone. Cartilage is divided into hyaline cartilage, elastic cartilage, and fibro cartilage.

Hyaline cartilage is found in the nose, larynx, trachea, and bronchi.

Elastic cartilage is found in the epiglottis and the cartilages of the larynx.

Fibro cartilage is found at the point of insertion of the ligaments, into the body of the bone, such as the cartilage which helps to hold the femur or long bone of the thigh into the hip.

Bones.

—Bone results from the calcification of cartilage or fibrous tissue. It is a highly specialized form of connective tissue. There are two varieties of bone; dense or compact bone and cancellous, loose, or spongy bone. Compact bone is dense, like ivory, and is always found on the exterior of bones.

Cancellous bone is found in the interior of bones, and has a lattice-work appearance.

Bone consists of one-third animal or organic matter and two-thirds earthy or inorganic matter. These proportions, however, vary with age. In youth it is nearly half and half, while in the adult the earthy is greatly in excess. It also varies with disease. With some defect of nutrition, the bone is deprived of its normal proportion of earthy matter, while the animal matter is of unhealthy quality, and we have as a result, a disease called rickets, so common in the children of the poor. The earthy or inorganic matter consists of phosphate, carbonate, fluoride of calcium, sodium chloride, and phosphate of magnesium. The animal matter consists of fat collagen, which when boiled with water is resolved into gelatin.

To illustrate the two substances, take a bone and place it in dilute hydrochloric acid. The acid will eat out all the mineral matter and we have left only the animal matter. After this operation one can take the bone and can bend it into any position whatever, which experiment shows that the animal matter gives elasticity to the bone.

The second experiment would be to put the bone on a bed of hot coals and burn it. Only the animal matter will burn and we will have the mineral matter remaining. After this operation one will find that the bone is very brittle and will easily break, which experiment shows that the mineral matter gives stability and support to the bone.

Fig. 5—Cross section of bone. (Sharpey)

If a cross section is made of any long bone, such as the humerus, and this section placed under the low power of the microscope, the Haversian canal system can be discerned. The Haversian canal system consists of the numerous small openings or canals through which the blood vessels ramify in distributing the nourishment to the bone. Around each individual canal are seen smaller spaces arranged in a circle. These are known as the lacunae (small lakes). Going from the lacunae are smaller canals which take on the name canaliculae, and joining all the lacunae together, making the appearance of concentric circles, we have the lamellae. The outside covering of the bone is called the periosteum and the inside covering is called the endosteum. Most of the long bones and many of the smaller bones are supplied by a nutrient artery, which enters the bone near its center, enters the bone marrow, and divides into two branches, one going up and the other down in the marrow. The blood is then distributed through the Haversian canal system. Veins emerge from the long bones in three places: 1. One or two large veins accompany the nutrient artery. 2. Numerous veins emerge from the articular extremities. 3. Many small veins arise in and emerge from the compact substance.

Bones are divided, according to shape, into four classes: long, short, flat and irregular.

Long Bones.—These bones are usually used as a system of levers to confer the power of locomotion. A long bone consists of a shaft and two extremities. The shaft is a hollow cylinder within which is the medullary canal. The extremities are somewhat expanded for the purpose of articulation, and to afford a broad surface for the attachment of muscles. The long bones are as a rule curved in two directions to give greater strength to the bone. Some examples of this class of bone are the clavicle, radius, ulna, humerus, femur, tibia, fibula, metacarpal, metatarsal, and the phalanges.

Short Bones.—These bones are placed in that part of the skeleton where there is need for strength and compactness, and where the motion of the part is slight and limited. Some examples of this class of bone are the bones of the carpus and tarsus (in the hand and the foot).

Flat Bones.—Flat bones are found where the principle requirement is either extensive protection, or the need of a broad surface for the attachment of muscles. Some of the bones of this class are the occipital, parietal, frontal, nasal, lachrymal, vomer, scapula, sternum, and the ribs.

Irregular Bones.—These bones are such as from their peculiar shape and form can not be grouped under any of the preceding heads. Some of the bones of this class are the vertebrae, sacrum, coccyx, temporal, sphenoid, ethmoid, etc.

If the surface of a bone is examined, certain articular and non-articular eminences and depressions will be seen.

Articular Eminences.—Examples of this class are found in the heads of the humerus and the femur.

Articular Depressions.—Examples of this class are found in the glenoid cavity of the scapula and the acetabulum.

Non-articular Eminences.—These are designated according to their form.

A tuberosity is a broad, rough, and uneven elevation.

A tubercle is a small, rough prominence.

A spine is a sharp, slender, pointed eminence.

A ridge, line, or crest is a narrow, rough elevation, running some way along the surface.

Non-articular Depressions.—These are of variable form, and are described as notches, sulci, fossae, grooves, furrows, fissures, etc. These non-articular eminences and depressions may serve to increase the extent of surface for the attachment of ligaments and muscles or may receive blood vessels, nerves, tendons, ligaments, or portions of organs.

Canals or foramina are channels or openings in bone through which pass the nerves and blood vessels.

Teeth.

—In the human body we find two sets of teeth. One appearing in childhood, and are known as milk teeth, twenty in number, the permanent teeth replacing these about the sixth year.

There are thirty-two permanent teeth, divided into four incisors, two canines, four bicuspids and six molars.

Teeth are made up of three different substances, which are known as enamel, dentine and cement.

The enamel is a very hard substance, the hardest in the body, and may be compared to quartz. The enamel covers the entire tooth down as far as the gums.

The cement is a continuation of the enamel below the gums, and is closely adherent to the dentine. The cement consists of bone tissue, but the lamellae as a rule do not contain Haversian canals.

The dentine is, next to the enamel, the hardest tissue of the tooth, and composes the main body of the tooth. The pulp cavity is found within the center of the tooth, with the opening toward the jaw bone. The tooth is nourished by a nutrient artery and vein and nerve which pass into the pulp of the tooth.

Nerves.

—Nerves are divided into two general classes, called medullary and non-medullary nerves. The non-medullated type arise mostly from the sympathetic system, while the medullated type arise from the brain and cord. As a rule, the nerves of the body follow the course of the arteries, and are generally found in the same sheath with the artery and vein.

Fig. 6—Section of a nerve fibre. (Klein and Noble Smith)

They are easily distinguished from the arteries and veins by touch and by their color, being very inelastic and fibrous, hard to the touch, and unlike the artery or vein, since they have no central opening.

Muscles.

—Myology is that branch of anatomy which treats of the muscles. The muscles are formed of bundles of reddish fibres, endowed with the property of contractility. In the body we find two kinds of muscular tissue, called voluntary and involuntary muscle. The voluntary type is characterized by the striped appearance which it displays when seen under the microscope, and for this reason it is called striped or striated muscle. It is so named “voluntary” because it is capable of being put into action and controlled by the will. The involuntary muscles do not present any striped appearance, and consequently are called unstriped or non-striated, and are not under the control of the will. An example of voluntary muscle would be any muscle of the bony framework as for example, the biceps or triceps.

Fig. 7—View of muscle fibers.

An example of involuntary muscle would be those of the intestines and stomach, the muscles of the bladder and uterus and the walls of the arteries and veins, etc.

When viewed under the microscope, the muscle is seen to be composed of many fibrils. The sheath covering each fibril is called the sarcolemma, and contains within its boundaries the muscle plasma, or protoplasm, and a nucleus. Many of the fibrils when grouped together constitute the entire muscle.

The muscles get their blood supply from the nutrient artery, which ramifies the tissues, the smallest capillaries coming in contact with each muscle cell.

Tendons.

—Tendons are white, glistening, fibrous cords, varying in length and thickness, sometimes round, sometimes flattened, of considerable strength, and devoid of elasticity. It consists principally of a substance which yields gelatin.

Tendons do not have a direct blood supply.

Aponeuroses.

—Aponeuroses are flattened or ribbon-like tendons, of a pearly-white color, irridescent, glistening, and similar in structure to the tendons.

Ligaments.

—Ligaments consist of bands of various forms, serving to connect the articular extremities of bones. They are strong bands of smooth, silverwhite fibrous tissue.

A ligament is pliable and flexible, so as to allow the most perfect freedom of movement, but at the same time it is tough and strong, so as not to yield readily under the severe applied force, and for this reason they serve as good connecting links for the binding of bones together.

Poupart's Ligament.—Poupart's ligament extends from the crest of the ilium to the top of the pubic bone. This ligament is of utmost importance to the embalmer, as it serves as a guide to locate the femoral artery. By placing the thumb on the crest of the ilium and the second finger on the top of the public bone, then letting the first finger drop midway between the two, which would be the center of Poupart's ligament, we have a point which marks the exit of the artery from the body and the beginning of the femoral artery.

Poupart's ligament also forms the base of Scarpa's triangle. The structure of this triangle will be taken up later.

Fat.

—Fat is a deposit of an oil in the cells of the tissues, just beneath the skin, giving roundness and plumpness to the body, and acting as an excellent non-conductor for the retention of heat.

So tiny are these cells, that there are over sixty-five million in a cubic inch of fat. As they are kept moist, the liquid does not ooze out; but, on drying, it comes to the surface, and thus a piece of fat feels oily when exposed to the air. The quantity of fat varies with the state of nutrition. In corpulent persons, the masses of fat beneath the skin, in the mesentery, on the surface of the heart and the great vessels, between the muscles, and in the neighborhood of the nerves, are considerably increased. Conversely, in the emaciated we sometimes find beneath the skin cells which contain only one oil drop. Many masses of fat which have an important relation to muscular actions—such as the fat of the orbit or the cheek, do not disappear in the most emaciated persons. Even in starvation, the fatty substance of the brain and spinal cord are retained.

Fat collects as pads in the hollows of the bones, around the joints and between the muscles, causing them to glide more easily upon each other. As marrow, it nourishes the skeleton, and also distributes the shock of any jar the limb may sustain.

Fat does not gather within the cranium, the lungs or the eyelids, where its accumulation would clog the organs.

Mucous Membranes.

—Mucous membranes line all the open cavities of the body, or all those cavities which communicate with the outside.

At the edges of the openings into the body, the skin seems to stop and give place to a tissue which is redder, more sensitive, more liable to bleed, and is moistened by a fluid or mucous, as it is called. Really, however, the skin does not cease, but passes into a more delicate covering of the same general structure, and it is to this that the name mucous membrane is applied.

The entire alimentary canal, the entire respiratory tract, and the genito-urinary tract, are lined with a mucous membrane. Mucous membrane secretes a mucous fluid.

Serous Membranes.

—Serous membranes line the closed cavities of the body. The pleurae, the pericardium and the peritoneum are examples of serous membranes. Serous membranes secrete a serous fluid.

Synovial Membranes.

—Synovial membranes are serous in character, and consist of loose connective tissue, containing fat, vessels and nerves, its inner surface being usually lined with secreting cells. The fluid secreted is yellowish-white or slightly reddish, resembling very much the white of an egg. It contains fats, salts, albumen, extractives from the lymph, and a fluid known as synovia. The chief function of this fluid is to act as an oil to lubricate the joints and surfaces in which there is any friction.

Synovial membranes are divided into three classes, known as articular, bursal and vaginal.

Articular synovial membranes are found in every free movable joint.

Bursal synovial membranes are sacs interposed between the surfaces which move upon each other, producing friction, as in the gliding of a tendon or of the integument over projecting bony surfaces.

Vaginal synovial membranes serve to facilitate the gliding of a tendon in the bony canal through which it passes.

Fig. 8—Section of artery. (Grunstein)

Arteries.

—The arteries are cylindrical vessels which serve to convey the blood from both ventricles of the heart to every part of the body. They are called arteries from the Greek words which mean “to contain air,” and they were supposed, by our ancients, to have this function until the time of Galen, when he refuted this opinion and showed that these vessels, though for the most part empty after death, actually contained blood. The distribution of the arteries may be compared to a tree, the common trunk of which corresponds to the aorta, and the smallest twigs corresponding to the minute capillaries. When one artery communicates with another it is said to anastomose, and this communication is very free between the larger as between the smaller branches. Anastomosis between trunks of equal size is found where great activity of the circulation is requisite, as at the base of the brain, where the two vertebrals unite to form the basilar artery.

In the limbs and arms the anastomoses are more numerous and of larger size around the joints. The branches of the artery above, unite with branches, from the vessels below. These anastomoses are called collateral circulations. The principal ones of interest to the embalmer are those of the deep brachial uniting with the recurrent radial and ulnar arteries, forming the collateral circulation in the arm; the deep femoral uniting with the recurrent posterior and anterior tibials, forming the collateral circulation in the leg; the superficial and deep mammary arteries, branches of the subclavian artery uniting with the superficial and deep epigastric arteries, branches of the external iliac, forming the collateral circulation over the abdomen and chest, and may be considered the longest collateral circulation in the body.

A terminal artery is one which forms no anastomoses; such vessels are found in the heart, brain, spleen, kidneys, lungs and mesentery.

Structure.—An artery consists of an internal, a middle and an external coat.

The inner coat consists of endothelial cells and elastic fibrous tissue, sometimes arranged longitudinally, but usually they form a distinct fenestrated membrane (similar to a doorscreen).

The middle coat consists mostly of elastic tissue and white fibrous tissue.

The external coat is called the fibrous coat. It contains fibrous connective tissue and elastic tissues.

Vasa-Vasorum.—Running in the outer wall of the artery, we find small capillary vessels, and their function is that of nourishing the outer wall, for the blood which passes through the artery does not nourish the artery from within, but depends on these small capillaries, called vasa-vasorum, for their nutrition.

The individual sheath, or arterial sheath, the covering for the artery, is composed of connective tissue, and at places may adhere very tightly to the artery.

Fig. 9—Valves of the veins.

Fig. 10—Cross section through a small artery and vein. (Klein and Noble Smith)

Veins.

—The veins are the vessels which carry the blood from the capillaries back to the right auricle of the heart, and are found in nearly every tissue of the body. They commence as venous capillaries, uniting together into larger and larger veins, until we have the great ascending and descending venae cavae. In form the veins are perfectly cylindrical, like the arteries, but with this difference, that their walls collapse when empty and that they contain valves.

Structure.—The vein has about the same structure as the artery, only that the middle coat is much thinner and less elastic than the artery, and for this reason it easily collapses.

Veins are divided into superficial, deep and sinuses. Superficial veins are found between the layers of the superficial fascia, just underneath the skin.

Deep veins accompany the arteries, and are usually enclosed in the same common sheath with the artery.

Sinuses are venous channels, which in their structure and mode of distribution differ altogether from the veins. They are found only in the interior of the skull, and consist of channels formed by a separation of the two layers of the dura mater.

Fig. 11—Human blood.

Blood.

—The blood of the body is contained in a practically closed system of tubes, the blood vessels, within which it is kept circulating by force of the heart beat. It is usually spoken of as the nutritive liquid of the body, but the functions may be stated explicitly, although still in quite general terms, by saying that it carries to the tissues food stuffs after they have been properly prepared by the digestive organs; that it transports to the tissues oxygen, absorbed from the air by the lungs; that it carries from the tissues various waste products formed in the processes of dissimilation; that it is the medium for the transmission of the internal secretion of certain glands; that it aids in equalizing the temperature and water contents of the body.

The total quantity of blood in the body has been determined approximately for man as one-thirteenth of the body weight. The specific gravity of human blood in the adult may vary from 1.041 to 1.067, the average being about 1.055.

The blood is composed of a liquid part, the plasma, in which float a vast number of microscopical bodies, the blood corpuscles, known respectively as the red corpuscles, the white corpuscles or leucocytes, of which in turn there are a great many different kinds, and the blood plates.

Blood plasma, when obtained free from corpuscles, is perfectly colorless, in thin layers, for example, in microscopical preparation; when seen in large quantities it shows a slightly yellowish tint. The red color of the blood is not due, therefore, to coloration of the blood plasma, but is caused by the mass of red corpuscles held in suspension in the liquid. The proportion by bulk of plasma to corpuscles is usually given roughly as two to one. The blood plasma is composed of two substances, blood serum and blood fibrin. You have noticed that blood, after it has escaped from the vessels, usually clots or coagulates. The clot, as it forms, gradually shrinks and squeezes out a clear liquid, to which the name blood serum has been given. Serum resembles the plasma of normal blood in general appearance, but differs from it in composition. Here it is sufficient to say that blood serum is the liquid part of the blood after coagulation has taken place. You can prepare this experiment for yourself: If shed blood is whipped vigorously with a rod or some similar object while it is clotting, the essential part of the clot, namely the fibrin, forms differently from what it does when the blood is allowed to coagulate quietly. It is deposited in shreds on the whipper. Blood that has been treated in this way is known as defibrinated blood. It consists of blood serum plus the red and white corpuscles, and as far as appearances go it resembles exactly the normal blood; it has lost, however, its power of clotting.

Red blood corpuscles are bi-concave, circular disks, without nuclei; their average diameter is 7.7 microns (1 micron equals 1-25,000 of an inch); their number, which is usually reckoned as so many to a cu. millimeter, varies greatly under different conditions of health and disease. The average number is given as 5,600,000 per cubic millimeter for males and 4,500,000 per cubic millimeter for females.

The number of red corpuscles also varies in individuals with the constitution, nutrition and manner of life. It varies with age, being greatest in the fetus and in the new-born child. It varies with the time of the day, showing a distinct diminution after meals. In the female it varies somewhat with menstruation and pregnancy, being slightly increased in the former and diminished in the latter condition.

The red color of the corpuscles is due to the presence in them of a pigment, known as hemoglobin. Owing to the minute size of the corpuscles, their color when seen singly under the microscope is a faint yellowish red, but when seen in mass they exhibit the well-known blood-red color, which varies from a scarlet in arterial blood to a purplish red in venous blood, this variation in color being dependent upon the amount of oxygen contained in the blood in combination with the hemoglobin. The function of the red blood corpuscles is to carry oxygen from the lungs to the tissues. This function is entirely dependent upon the presence of hemoglobins, which have the power of combining easily with the oxygen gas.

White blood corpuscles or leucocytes contain no hemoglobin or coloring matter. They have a nucleus or center spot. Their size varies from 5 to 12 microns, and are less numerous than the red corpuscles, being in this proportion: one white corpuscle to 500 red corpuscles. The chief functions of the white corpuscles are: (1) That they protect the body from pathogenic or disease-producing bacteria. In explanation of this action it has been suggested that they may either ingest the bacteria and thus destroy them directly, or they may form certain substances, defensive proteids, that destroy the bacteria. White corpuscles that act by ingesting the bacteria are spoken of as phagocytes (meaning to eat the cell). (2) They aid in the absorption of fats from the intestines. (3) They aid in the absorption of peptones from the intestines. (4) They take part in the process of blood coagulation. (5) They help in maintaining the normal composition of the blood plasma in proteids.

Blood plates are small circular or elliptical bodies, nearly homogeneous in structure, variable in size, always much smaller than the red blood corpuscles. Less is known of their origin, fate and functions than in the case of the other blood corpuscles, but there is some considerable evidence to show that they take part in the process of coagulation or clotting.

Coagulation of the Blood.—One of the most striking properties of the blood is its power of clotting, or coagulating, shortly after it leaves the blood-vessels, or if any foreign elements come in contact with it. The general changes in the blood during this process are easily followed. At first perfectly fluid, in a few minutes it becomes viscous, and then sets into a soft jelly, which quickly becomes firmer, so that the vessel containing it can be inverted without spilling the blood. The clot continues to grow more impact, and gradually shrinks in volume, pressing out a greater or smaller amount of clear, faintly yellow liquid, to which the name blood serum is given. The essential part of the clot is the fibrin.

Fibrin is an insoluble proteid not found in normal blood. In shed blood, and under certain conditions while still in the blood-vessels, this fibrin is formed. In forming, it shows an exceedingly fine network of delicate threads that permeate the whole mass of the blood and gives the clot its jelly-like character. The shrinking of the threads causes the subsequent contraction of the clot. If the blood has not been disturbed during the act of clotting, the red corpuscles are caught in the fine fibrin mesh-work, and as the clot shrinks these corpuscles are held more firmly, only the clear liquid of the blood being squeezed out, so it is possible to get specimens of serum containing few or no red blood corpuscles. The white corpuscles or leucocytes, on the contrary, although they are also caught at first in the forming meshes of fibrin, in latter stages of the clotting they readily pass out into the serum, on account of their power of having movement. If the blood has been agitated during the process of clotting, the delicate net work will be broken in places, and the serum will be more or less bloody—that is, it will contain numerous red blood corpuscles. If during the time of clotting the blood is vigorously whipped with a bundle of fine rods, all the fibrin is deposited as a stringy mass on the whipper, and the remaining liquid part consists of serum plus red corpuscles. Blood that has been whipped in this way is known as defibrinated blood. It resembles normal blood in appearance, but is different in composition; it can not clot again. The way in which fibrin is normally deposited can be easily demonstrated by taking a drop of blood on a slide and covering it with a cover slip, allow it to stand several minutes until coagulation is complete, and view under a microscope. If the drop is examined, it is possible by careful focusing, to discover in the spaces between the masses of corpuscles many examples of delicate fibrin net work. The physiological value of the clotting of blood in life is that it stops hemorrhages by closing the openings of the wounded blood vessels, but the clotting of the blood after death, is to the embalmer one of the bugbears, and a real method of preventing it, or of dissolving the clot after it has once formed in the blood vessels is one of those difficult problems which remains as yet unsolved.

Since we have no real method of preventing coagulation in the blood vessels, let us search out the things which will hasten or retard this coagulation. Blood coagulates normally within a few minutes after it is liberated from the blood vessel, but this process may be hastened by increasing the amount of foreign substance with which it comes in contact. Thus the agitation of the liquid in quantity or the application of a sponge or handkerchief or the application of heat hastens the onset of clotting.

Coagulation in drawn blood may be retarded or prevented altogether by a variety of means, of which the following are the most important:

(1) By cooling.

(2) By the action of neutral salts.

(3) By the action of oxalate solutions.

(4) By the action of sodium fluoride.

Summary.—To summarize then, the following statements may be made:

(1) The immediate factor necessary to the clotting of the blood is the fibrin.

(2) That blood does not clot normally in the blood vessels before death.

(3) That after death blood remains for a long time without clotting, provided some outside agent is not introduced to cause it.

Such an agent may be the blood coming in contact with the air, or the blood drainage tube. The one point then to be emphasized is that when a vein is cut, and the blood begins to flow, you know that the blood is not in a coagulated condition. Then work rapidly, put the blood drainage tube quickly into the vein and draw off as much blood as you can before it begins to clot at the end of the tube. The great trouble has been, that the embalmer does not work with precision. He first raises the vein, and exposes it on the surface of the incision. He then raises the artery. He places the drainage tube into the vein, but shuts it off till he is ready with the artery. Now, by the time he has placed the arterial tube in the artery, injected a few bulbs full to see that all is in working order, and has perhaps attended to a few other duties, he is amazed to find that the blood will not flow, that it has clotted. What is the reason? He gave it time to clot after the drainage tube was inserted.

A better procedure would be not to touch the vein until every other procedure has been attended to. Then raise the vein, insert the drainage tube and withdraw the blood quickly, and at the same time keep injecting slowly into the arterial system to keep up the needed pressure to keep the blood flowing.

(4) That when a clot is once formed in a blood vessel, it is not dissolved by the addition of fluid or any other solution.

(5) That sometimes when the blood has become clotted at the end of the drainage tube, it can be loosened up or be slightly pushed away by attaching the pump to the drainage tube and injecting a few bulbs of fluid, which, when it runs out, will again start the flow of blood.

CHAPTER V. OSTEOLOGY.

Definition.

—Osteology is the science of the structure and functions of bones.

In regard to the treatment of this subject, it is not our aim to take up all the minute details concerning each bone, all we desire is to explain the form, uses and location of some of the principle bones and sets of bones of the body in so far as they may come to be used as landmarks for the embalmer.

The Skeleton.

—The entire skeleton in the adult consists of 200 distinct bones.

Fig. 12—The Skeleton.

Spine—
	Cervical	7
	Dorsal	12
	Lumbar	5
	Coccygeal	1
	Sacral	1
		26		26
Cranium				8
Face				14
Hyoid				1
Sternum				1
Ribs—
	True	7	Pair
	False	3	“
	Floating	2	“
		12	“	24
Upper Extremities				64
Lower Extremities				62
				200

In the above outline the bones of the ear and the sesamoid bones are not considered. Different anatomists make different computations as to the number of bones in the skeleton. Some authorities add the bones of the ear, thus making 206 in all. If all the little sesamoid bones were added, the number could be greatly augmented.

The Vertebral or Spinal Column. (The Spine).

—The spine is a flexuous and flexible column formed of a series of bones called vertebrae. There are twenty-six in number and may be divided as follows:

Cervical	7	bones
Dorsal	12	“
Lumbar	5	“
Sacral	1	“
Coccygeal	1	“

Fig. 13—The Spine.

The cervical vertebrae are smaller than those in any other region of the spine, and may be readily distinguished as they lie in the neck and extend from the base of the skull to the dorsal vertebrae, or the point of attachment of the first rib to the first dorsal.

The dorsal or thoracic vertebrae are the next in rotation down the spine and are intermediate in size between those in the cervical and those in the lumbar region, and increase in size from above downward.

The lumbar vertebrae, the next in rotation, are the largest of the vertebral column and can be distinguished as those lying in the lumbar region or the small of the back.

The sacrum, meaning sacred, so called, because it was the part selected in sacrifices. The sacrum is a large triangular bone, situated at the lower part of the vertebral column, and at the upper and back part of the pelvic cavity.

The coccyx, so called from having been compared to a cuckoo's beak. It is usually formed of four small segments of bones, and gradually diminish in size from above downward, and blend together so as to form a single bone.

The spinal column is situated in the median line, at the posterior part of the trunk. Its average length is about two feet, two or three inches. The female spine is about one inch shorter than the male.

The spinal canal in which runs the spinal cord, follows the different curves of the spine; the opening being the largest in those regions in which the spine enjoys the greatest freedom of movement, and the smallest where motion is more limited.

The Skull.

—The skull is the bony framework of the head. The cranium is the name applied when we do not consider the mandible (the lower jaw).

The skull is oval in shape, wider behind than in front, and is supported on the summit of the vertebral column.

The skull is composed of twenty-two bones and is divided as the following diagram will show:

Fig. 14—The Skull.

	Cranium	Occipital
		Two parietal
		Frontal
Skull		Two temporal
		Sphenoid
		Ethmoid
		Two inferior turbinate
		Two nasal
		Two superior maxillary
	Face	Two lachrymal
		Two malar
		Two palate
		Inferior maxillary
		Vomer

The Bones of the Cranium.

—Occipital Bone.—The occipital bone is situated at the back part and base of the cranium.

Frontal Bone.—The frontal bone is situated at the anterior part of the cranium, and forms the forehead.

Parietal Bones.—The parietal bones, two in number, form, by their union, the sides and roof of the cranium. They are between the frontal and the occipital bones.

Temporal Bones.—The temporal bones, two in number, are situated at the sides and base of the skull.

Sphenoid Bone.—The sphenoid bone is situated at the anterior part of the base of the skull articulating with all the other cranial bones.

Ethmoid Bone.—The ethmoid is an exceedingly light, spongy bone, which is situated at the anterior part of the base of the cranium.

The Bones of the Face.

—Nasal Bone.—The nasal bones, two in number, are placed side by side at the middle and upper part of the face, forming, by their junction, “the bridge” of the nose.

Superior Maxillary Bones.—The superior maxillae, two in number, are the largest bones of the face, excepting the lower jaw, and form by their junction, the upper jaw.

Inferior Maxillary Bone.—The inferior maxillary bone is also called the mandible. This bone is the largest and strongest bone of the face. In a great many cases after death this bone drops down, and it becomes one of the first duties of the embalmer, to place this bone in the proper position, so that it will set with the gradual death stiffening. If the lower jaw has already set, in proper position, it is best not to break up the rigor, because, once broken up, it will be hard to set it in proper condition again without the use of stitches.

The upper and lower jaws are the fundamental bones for mastication.

Lachrymal Bones.—The lachrymal bones, two in number, are the smallest and most fragile bones of the face. They are situated at the front part of the inner wall of the orbit of the eye.

Malar Bones.—These are the cheek bones. There are two in number, situated at the upper and outer part of the face.

Palate Bones.—The palate bones, two in number are situated at the back part of the nasal fossae. Each bone assists in the formation of three cavities: the floor and the outer wall of the nose, the roof of the mouth, and the floor of the orbit.

Inferior Turbinated Bones.—The inferior turbinated bones are situated one on each side of the outer wall of the nasal fossae.

Vomer.—The vomer, a single bone, is situated vertically at the back part of the nasal fossae, forming part of the septum of the nose. It is thin and somewhat like a ploughshare in form.

The Hyoid Bone.

—The hyoid bone is named from its resemblance to the Greek letter U. It is also called the lingual bone, because it supports the tongue and gives attachment to its numerous muscles.

The omo-hyoid muscle, which crosses the carotid artery at its middle third, has its insertion with the hyoid bone.

The Bones of the Thorax.

—The Sternum or Breast Bone.—The sternum is a flat, narrow bone, situated in the median line of the front of the chest. The lower end is called the ensiform process, to which the diaphragm has its anterior attachment.

The Ribs.—The ribs, which are curved arches of bone, form the chief part of the thoracic walls. There are twelve in number on each side, although this number may vary.

The ribs are divided into seven pairs of true ribs, three pairs of false ribs, and two pairs of floating ribs, as the following outline will show:

• Ribs
• 7 true
• 3 false
• 2 floating
• —
• 12 pairs in all.

The true ribs are connected behind to the spine and in front to the sternum.

The false ribs are connected behind to the spine, but are called false because they are not attached directly to the sternum, but indirectly, the cartilages attaching to the cartilage of the rib next above.

The floating ribs are so named because they are only attached at one place, which is the spine and are loose or float in front.

The Bones of the Upper Extremities.

—The Shoulder girdle consists of the clavicle and scapula.

The Clavicle.—The clavicle or key bone, so-called because of its supposed resemblance to the key used by the Romans, forms the anterior portion of the shoulder girdle. It is often commonly called the collar bone.

The Scapula.—The scapula comes from a Greek word meaning “a spade.” It forms the back part of the shoulder girdle.

The arm is that portion of the upper extremity which is situated between the shoulder and the elbow.

The Humerus.—This is the largest and strongest bone of the upper extremity and is found in the arm between the shoulder and the elbow. It is the only bone in the arm.

The fore arm is that portion of the upper extremity which is situated between the elbow and the wrist. The fore arm has two bones, the ulna and the radius.

The Ulna.—A long thin bone, but larger than the radius, and situated on the inside of the fore arm.

The Radius.—So-called because it is the rotary bone of the fore arm. It is situated on the outside of the fore arm and parallel with the ulna.

The hand is subdivided into the wrist or carpus bones, the metacarpus or the bones of the palm, and the phalanges or the bones of the digits. There are twenty-seven bones in each hand.

The Bones of the Lower Extremities.

—The bones of the lower extremities consist of the pelvic girdle, the thigh, the leg and the foot.

The pelvic girdle consists of three portions, the ilium, the pubis, and the ischium.

The Ilium.—The ilium is the superior, broad and expanded portion and forms the prominence of the hip. The top part is called the crest.

The Ischium.—The ischium is the lowest portion of the girdle, and is the portion which supports the body when in a sitting position.

The Pubis.—This bone forms the front of the pelvis, and supports the external organs of generation.

The thigh is that portion of the lower extremity which is situated between the pelvis and the knee. It consists of a single bone called the femur.

The Femur.—The femur is the largest, longest and strongest bone in the skeleton. It is almost perfectly cylindrical. It extends from the hip to the knee.

The bones of the leg are three in number and are as follows: patella, tibia, and fibula.

The Patella.—This bone is often called the knee cap or the knee pan. It is a flat triangular bone, situated at the anterior part of the knee joint.

The Tibia.—The tibia is situated at the front and inner side of the leg, and is next to the femur in strength and size. It is sometimes called the shin bone.

The Fibula.—The fibula is sometimes called the calf bone. It is situated at the outer side of the leg, and is a quite slender bone.

The foot is divided into the tarsus, metatarsus, and the phalanges. There are seven tarsus bones, five metatarsus bones, and fourteen phalanges bones, making a total of twenty-six bones for each foot.

CHAPTER VI. ORGANOLOGY.

The body itself is divided into the upper and the lower extremities and the trunk. The upper extremities consist of the head and arms. The lower extremities consist of the legs. The trunk is that part of the body remaining after the head, arms, and legs have been severed from the body.

In the cranial cavity we find the brain. The brain is the seat of the mind, and the functions which the brain performs distinguishes man from the other animals, as man becomes a conscious, intelligent, responsible being through the action of the brain. The brain is egg-shaped, soft and yielding, closely fitting the cranial cavity. The front and top of the brain is called the cerebrum, which is the center for intelligence, reason, and will. This part of the brain is convoluted, and the depth of the convolutions to a great extent indicates the amount of intelligence.

Below the cerebrum and lying in front of the occipital bone, we find the cerebellum, which is the seat of memory and the center for the co-ordination of muscle movements. By co-ordination of muscle movement is meant that the muscles will do just what we want them to do, that they will act harmoniously, the one with the other. The condition of Saint Vitus' Dance would be an example showing a lack of co-ordination. This part of the brain is also convoluted.

Between the cerebrum and the cerebellum, and connecting the two, is found the pons Varolii. The word pons means bridge, and the word Varolii means to cross over. It is in this part of the brain, then, that the nerve fibers cross over to the opposite side. A person having a paralytic stroke on the right side of the body would indicate that the left side of the brain had become affected.

Joined to this is the medulla oblongata. This is the lowest part of the brain and is the connecting link between the brain and the spinal cord. The medulla controls the circulation, respiration, and deglutition (swallowing).

Closely adhering to the brain, is a delicate membrane, sinking into the convolutions, and following the surface of the brain valleys throughout. This membrane is called the pia mater. In it is found the capillaries, which supply the brain with its nutritive blood in life and with embalming fluid after death. These capillaries do not penetrate the substance of the brain, but the process is one of osmosis, absorption or transfusion. Covering the outer most part of the brain, and closely adhering to the cranial bones is a dense, tough, glistening, membrane, called the dura mater. In the dura mater is found the sinuses of the brain.

In between the pia mater and the dura mater is a delicate double membrane forming a closed sack, called the arachnoid membrane. This sac contains a serous fluid, which offers great protection to the brain. These same three membranes also cover the spinal cord, and are called all together the meninges of the brain and cord.

The brain is composed of white and gray matter. The gray matter is on the outside, and the white matter is on the inside.

The spinal cavity is formed by the bones of the vertebral column. In this spinal cavity is found the spinal cord. It is cylindrical and usually about seventeen inches in length, and extends from the medulla oblongata, to the lower border of the first lumbar vertebra, where it terminates in a slender filament of gray substance.

There originate from the under surface of the brain twelve pairs of nerves, as follows:

• 1. Olfactory
• 2. Optic
• 3. Motor Oculi
• 4. Trochlear
• 5. Trigeminal
• 6. Abducens
• 7. Facial
• 8. Auditory
• 9. Glosso-pharyngeal
• 10. Pneumogastric
• 11. Spinal accessory
• 12. Hypoglossal

There originate from the cord thirty-one pairs of nerves, as follows:

The circulation of the blood through the brain will be taken up later.

CHAPTER VII. ORGANOLOGY.—Continued.

The thorax is bounded in front by the sternum and costal cartilages, behind by the twelve dorsal vertebrae and the posterior parts of the ribs, on the sides by the ribs, above by the root of the neck and below by the diaphragm.

In the female the thorax differs as follows from the male: Its general capacity is less, the sternum is shorter, and the upper ribs are more movable and so allow a greater enlargement of the upper part of the thorax than the male.

The capacity of the cavity of the thorax does not correspond with its apparent size externally, because, (1) the space enclosed by the lower ribs is occupied by some of the abdominal viscera; and (2) the cavity extends above the first rib into the neck. The size of the cavity of the thorax is constantly varying during life, with the movements of the ribs and diaphragm, and with the degree of distention of the abdominal viscera.

From the collapsed state of the lungs, as seen when the thorax is opened, in the dead body, it would appear as if the viscera only partly filled the cavity of the thorax, but during life there is no vacant space, that which is seen after death being filled up during life by the expanded lungs.

On either side of it lie the great blood vessels of the neck, behind it forms a part of the boundary of the pharynx, and is covered by the mucous membrane lining that cavity.

Its vertical extent corresponds to the fourth, fifth, and sixth cervical vertebrae. It is placed somewhat higher in the female than in the male.

The movements of the head affect the position of the larynx. When the head is drawn back, the larynx is lifted, and when the chin approaches the chest the larynx is depressed. During swallowing the larynx moves distinctly; during singing it moves slightly.

Until puberty there is no marked difference between the larynx of the male and that of the female. In the male after puberty all the cartilages increase in size, and the larynx becomes prominent as the Adam's apple in the middle line of the neck. In the female after puberty the increase of size is only slight.

The larynx is broad above, where it presents a triangular appearance, flattened behind and at the sides. Below it is narrow and cylindrical.

It is composed of cartilages which are connected together by ligaments and moved by numerous muscles. It is lined by a mucous membrane which is continuous above with the lining of the pharynx and below with that of the trachea.

The arteries that supply the larynx are the laryngeal arteries, branches of the superior and inferior thyroid arteries.

The superior laryngeal vein runs into the superior thyroid vein and then into the internal jugular vein, while the inferior laryngeal vein runs into the inferior thyroid vein and then into the innominate vein.

The trachea is in the median line of the body. It measures about four and one-half inches in length. The diameter is from three quarters to one inch, being always greater in the male than in the female.

The trachea is composed of imperfect cartilage rings, not coming quite together in the back.

The artery that supplies the trachea is the inferior thyroid artery.

The vein that withdraws the blood is the inferior thyroid vein.

The Right Bronchus.—The right bronchus is shorter, and wider than the left bronchus. It is about one inch in length. It enters the lung opposite the fifth dorsal vertebra.

The Left Bronchus.—The left bronchus is smaller and longer than the right. It is two inches in length and enters the lung at a point opposite the body of the sixth dorsal vertebra.

Each bronchus divides into smaller divisions called bronchial tubes.

Each bronchial tube divides into still smaller divisions called bronchioles.

Each bronchiole ends in the air cell.

The pulmonary pleura is the portion investing the surface of the lung, and dipping into the fissures between its lobes.

The parietal pleura is that which lines the inner surface of the chest.

The space between these two layers is called the cavity of the pleurae, (the pleural cavity); and contains nothing but a very little clear fluid.

In the healthy condition the two layers are in contact and there is no real cavity, but after death the lungs become collapsed and separate from the walls of the chest. Each pleura is therefore a shut sac, one occupying the right, and the other the left half of the thorax, and they are perfectly separated from one another. The two pleurae do not meet in the middle line of the chest, excepting for a short distance between the second and third pieces of the sternum—a space being left between them, which contains all the viscera of the thorax excepting the lungs; this is called the mediastinum.

The mediastinum then, is the space between the right and left pleural sacs.

The arteries of the pleura are derived from the intercostal, internal mammary, musculo-phrenic, thymic, pericardiac, bronchial.

The veins correspond to the arteries.

The root of the lung may be described as being that part where all the great blood vessels and the bronchial tubes, enter the lungs.

In many cases the lung does not hang free, but as a result of former pleurisy, the area of the pulmonary pleura is adherent to the parietal pleura.

Each lung is conical in shape, and presents for examination, an apex, a base, and two surfaces.

The Apex forms a tapering cone which extends into the root of the neck about an inch and a half to two inches above the level of the top of the first rib.

The Base is broad and concave and rests upon the convex surface of the diaphragm, which separates the right lung from the upper surface of the right lobe of the liver and the left lung from the upper surface of the left lobe of the liver, the stomach, and spleen.

Surfaces.—There are two in number. The external, costal or thoracic surface is smooth, convex and corresponds to the form of the cavity of the chest. The inner or mediastinal surface is concave, and the middle portion, where all the vessels enter and leave the lung is called the root.

Lobes.—Each lung is divided up into lobes. The right lung has three lobes, and the left lung has two lobes.

Weight.—The weight of both lungs together is about 42 ounces, the right lung being a little heavier than the left. The lungs are heavier in the male than in the female. The male lungs weigh from 42 to 45 ounces, and the female lungs weigh from 32 to 35 ounces.

Color.—The color of the lungs at birth is a pinkish white, in adult life a dark slate color, mottled in patches and as age advances this mottling assumes a black color.

Substance.—The substance of the lung is of a light porous, spongy texture. It floats in water, if it has once been filled with air. It is elastic and for this reason we always find the lung collapsed after death.

The structure of the lung is such that the blood brought by the pulmonary artery comes into close relation with the air in the air-cells which enters from the bronchioles. The blood gives off carbon dioxide to the air-cells and the air in the cells furnishes oxygen for the blood. The process of respiration causes the dark blood brought from the heart by the pulmonary arteries to return to the heart as red blood in the pulmonary veins.

Arteries.—The bronchial arteries supply the lungs with nutrition.

The pulmonary arteries convey venous blood from the heart to the lungs to be purified.

Veins.—The bronchial veins carry off the impure blood from the lungs.

The pulmonary veins convey the blood which has been purified by the lungs, back to the heart.

Within it are the contents of the thorax, excepting the lungs. The mediastinum may be divided into two parts.

The superior mediastinum is that portion of the interpleural space which lies above the level of the pericardium. This space contains the arch of the aorta, innominate, part of the left carotid artery, part of the left subclavian artery, the upper half of the superior vena cava, the upper half of the innominate vein, the left superior intercostal vein, trachea, esophagus, thoracic duct, remains of the thymus gland, etc.

The inferior mediastinum is divided into three portions:

The anterior mediastinum is that portion in front of the pericardium. It contains nothing but some loose areolar tissue.

The posterior mediastinum is that portion back of the pericardium. It contains the descending thoracic aorta, the greater and lesser azygos veins, the esophagus, the thoracic duct, etc.

The middle mediastinum is that part within the pericardium or heart sac. It is the largest space of all the mediastinal spaces. It contains the heart, the ascending aorta, the lower half of the superior vena cava, the vena azygos, the bifurcation of the trachea, the pulmonary artery, etc.

The middle mediastinum is sometimes called the cardiac cavity, because it contains the heart.

Behind we find the bronchi, esophagus and descending thoracic aorta. To the sides we find the pleura, the phrenic nerve and the accompanying vessels. In front we find the sternum and the remains of the thymus gland. It is attached above to the great blood vessels and below to the diaphragm.

The heart is placed obliquely in the chest. The base is directed upward, backward and to the right, and corresponds to the dorsal vertebrae from the fifth to the eighth inclusive.

The apex is directed downward, forward and to the left and corresponds to the space between the cartilages between the fifth and sixth ribs.

The exact location of the apex of the heart would be ¾-inch to the inner side, and an inch and one-half below the left nipple, or about three and one-half inches from the middle line of the sternum or breast bone.

The heart is placed behind the sternum, and extends about three inches to the left of the median line, and about one and one-half inches to the right, or in other words, about one-third of the heart lies to the right of the median line, and two-thirds lies to the left of the median line.

The heart in the adult measures five inches in length, three and one-half inches in breadth in its broadest part, and two and one-half inches in thickness. The weight of the male heart varies from ten to twelve ounces, and that of the female from eight to ten ounces.

The capacity of the ventricles of the heart averages about three and one-half ounces of blood to each ventricle, and the auricle a little less than four ounces, making the total capacity of the heart average about fifteen ounces.

The heart is divided by a muscular septum (separation wall) into two lateral halves, which are named respectively the right or venous side and the left or arterial side. The septum is called the longitudinal septum. Each side of the heart is further sub-divided into an upper and lower compartment, the upper on each side is called the auricle and the lower the ventricle. The upper and lower compartments of the heart (auricles and ventricles) are separated by the auricular-ventricular septums (meaning a separation between the auricle and ventricle).

The superior and inferior venae cavae empty into the right auricle of the heart, also the blood from the coronary sinus.

In fact, this compartment receives all the venous or impure blood from all parts of the body, and sends it through what is known as the tricuspid valve into the right ventricle or lower compartment. After getting into the right ventricle, the blood is sent forth into the lungs by first passing through the pulmonary semi-lunar valve into the pulmonary artery, which enters the lungs at the root of the same.

This would then finish the circulation through the right side of the heart, and after the purification has been accomplished by the lungs, we find the blood being returned to the left side of the heart through the four pulmonary veins. The pulmonary veins extend from the lungs (two on each side) to the left auricle (upper compartment of the heart) and deliver the purified blood to the left or arterial side. The course of the blood from the left auricle is downward into the left ventricle (or lower compartment) through what is known as the bicuspid or mitral valve.

The blood is then sent out into the body to nourish all the tissues, by being forced through the aortic semi-lunar valve into the great aorta artery. The circulation is then completed by the blood running into the branch arteries and from them into the smaller branches and into the capillaries from which the course of the blood is into the smaller veins and into the larger veins, finally terminating into the two large trunk veins, the ascending (or inferior) and descending (or superior) venae cavae. Of these two large trunk veins the ascending vena cava is the only one to have a valve at its termination (eustachian). The functions of this valve are to prevent a backward flow of blood into the vein from the auricle.

The heart has three walls, the inner wall is called the endocardium, the middle wall is called the myocardium, and the outer wall is called the epicardium.

The heart is surrounded by a serous sac called the pericardium.

The heart receives its blood supply from the coronary arteries, which are branches of the ascending aorta, just after it leaves the aortic semi-lunar valve.

The coronary veins bring the venous blood back from the tissues of the heart and empty into the coronary sinus, back of the right auricle of the heart.

The veins which originate about the region of the right auricle, empty directly into the right auricle of the heart through the valves of Thebesii.

The following outline will show the parts of the alimentary canal:

The accessory organs to the alimentary canal are the following:

Teeth, Salivary glands, Liver, Spleen, Pancreas.

In this cavity the mastication of the food and the insalivation of the food takes place.

The parotid gland is placed near the ear. The submaxillary gland is placed below the jaw. The sublingual gland is placed below the tongue.

These glands secrete the salival juices which are brought into the mouth by three small ducts, where it aids in the digestion of the food. The digestive action of the saliva is limited to the starchy foods. Its action is to change starches into sugars.

It also fulfills other important functions. By moistening the food it enables us to reduce the material to a consistency suitable for swallowing and for manipulation by the tongue and other muscles. The saliva also serves as a kind of lubricator that insures the smooth passage along oesophageal canal.

The pharynx is about four and one-half inches in length.

Seven openings communicate with it, as follows:

Two posterior nares, two eustachian tubes, mouth, larynx, esophagus.

It begins at a point between the fifth and sixth cervical vertebrae and descends along in front of the spine through the posterior mediastinal space, passes through the diaphragm, and entering the abdomen, terminates in the stomach wall at a point opposite the tenth dorsal vertebra.

At its commencement it is placed in the median line and gradually inclines to the left as it passes forward to the esophageal opening to the diaphragm.

The esophagus is from one-half to an inch in diameter.

Arteries.—The arteries which supply the esophagus are the esophageal, which are branches from the aorta.

Veins.—The esophageal veins empty into the ascending vena cava.

It is attached in front to the ensiform process of the sternum, on the sides to the inner surface of the cartilages and bony portions of six or seven inferior ribs, and behind it is attached to the lumbar vertebrae.

The diaphragm has three openings, as follows: opening for the esophagus, opening for the aorta, opening for the ascending vena cava.

The diaphragm is the principal muscle of respiration.

The arteries which supply the diaphragm are the phrenic arteries.

The phrenic veins receive the blood from the diaphragm.

CHAPTER VIII. ORGANOLOGY.—Continued.

To facilitate description, the abdomen is artificially divided into two parts:

An upper and larger part, the abdomen proper.

A lower and smaller part, the pelvis.

These two cavities are not separated from each other, but the limit between them is a line drawn around the brim of the true pelvis.

The abdomen proper differs from the other great cavities of the body, in being bounded for the most part by muscles and fascia.

It varies in capacity and shape according to the condition of the viscera which it contains and in addition, it varies in form and extent with age and sex.

Boundaries.—The diaphragm forms the dome over the abdomen, the cavity of the abdomen extending high into the bony thorax.

The lower end of the abdomen is limited by the bones of the pelvis.

In front and at the sides it is bounded by the lower ribs and abdominal muscles.

Behind by the vertebral column and muscles.

Regions.—For convenience of description of the viscera, the abdomen is artificially divided into nine regions. Thus if two circular lines are drawn around the body, the one at the extremities of the ninth ribs where they join the costal cartilages, and the other around the crest of the ileum, the abdominal cavity is divided into three zones.

If two parallel lines are now drawn perpendicular upward from the center of Poupart's ligament, each of these zones is subdivided into three parts.

The middle region of the upper zone is called the epigastric; and the two lateral regions, the right and left hypochondriac. The central region of the middle zone is called the umbilical; and the two lateral regions, the right and left lumbar regions. The middle region of the lower zone is called the hypogastric; and the two lateral regions are called the right and the left inguinal regions.

The viscera contained in each of these are as follows:

The lesser curvature of the stomach extends between the cardiac and the pyloric orifices along the right border of the organ.

The greater curvature of the stomach is directed to the left, and is four or five times as long as the lesser curvature.

The cardia is the point at which the esophagus enters the stomach wall.

The cardiac orifice is the opening by which the esophagus communicates with the stomach. It is sometimes called the esophageal opening. It is situated on a level with the body of the tenth and eleventh dorsal vertebrae. It is to the left of and in front of the aorta. On the anterior surface of the body the cardiac orifice corresponds to the articulation of the seventh left costal cartilage to the sternum.

The pylorus is the point at which the stomach passes into the duodenum.

The pyloric orifice is the opening by means of which the stomach communicates with the duodenum.

This orifice is guarded by the pyloric valve. When the stomach is empty the pylorus is situated just to the right of the median line of the body on a level with the upper border of the first lumbar vertebra. On the anterior surface of the body its position would be indicated by a point one inch below the tip of the ensiform process and a little to the right.

The size of the stomach varies considerable in different subjects. The distance between the two orifices is from three to six inches. The weight of the stomach is about four and one-half ounces.

The capacity of the adult male stomach is from five to eight pints. The stomach of a new born child holds about one ounce.

The stomach is held in place by the attachment of the esophagus to the diaphragm and the fixation of the duodenum to the front of the vertebral column.

The wall of the stomach consists of four coats: serous, muscular, areolar, and mucous.

The glands of the stomach are of three kinds: gastric, pyloric, and cardiac. These glands furnish the digestive enzymes of the stomach, namely: pepsin, renin, and hydrochloric acid.

Arteries.—The arteries that supply the stomach are the gastric, and branches from the splenic and the hepatic.

It must be remembered that when a body is arterially injected after death, that the fluid only goes to the stomach walls and there ends in the capillary system. No doubt a little of this fluid will soak through into the inside of the stomach, and tend to preserve the contents of the stomach, but it must be added that if the stomach contains a considerable quantity of food and water, that there will not be enough fluid soak through the stomach wall to preserve the contents of the stomach and as a result gases arise which cause distention of the abdomen and perhaps purging from the mouth and nose. As a rule then it is safe to say that when we have purging from the mouth and nose, with a visible distention of the abdominal cavity, indicating gases in the stomach and the intestines that fluid has not reached the contents of the stomach and the fecal matter of the intestines, and therefore it will be necessary to introduce fluid to these parts, in order to preserve the contents, and prevent further formation of gases. The method for doing this will be given under cavity embalming.

The small intestines are surrounded at the top and at the sides by the large intestines. The small intestines are held in place by the mesentery, a part of the peritoneum, which connects or fastens to the spine.

The small intestines are divisible into three portions: Duodenum, Jejunum, and the Ileum.

Arteries.—The main arterial supply to the small intestines is through the superior mesenteric artery.

The superior mesenteric vein withdraws the main part of the blood from the small intestines.

It is the shortest, widest and the most fixed part of the small intestines, being closely and firmly attached to the posterior abdominal wall. It is not covered by the mesentery. The upper half of the duodenum is in the epigastric region and the lower half is in the umbilical region. It is practically in the median line of the body.

The duodenum is shaped like a horseshoe, the opening being directed toward the left. The arteries supplying the duodenum are the pyloric and the pancreatic duodenal branch of the superior mesenteric. The veins correspond to the arteries.

The pancreatic duct and the bile duct empty into the duodenum at its middle portion.

It is wider, thicker, more vascular and of a deeper color than the ileum. The jejunum is about eight feet in length or two-fifths of the length of the small intestines.

The arteries which supply the jejunum are the branches of the superior mesenteric artery. The veins are of the same name.

The jejunum is fastened to the posterior wall of the abdomen by an extensive fold of the mesentery.

The villi are minute projections on the mucous membrane of the small intestines. They are largest and most numerous in the duodenum and jejunum, and become fewer and smaller in the ileum. It is in the villi of the intestines that we find the termination of the mesenteric arteries, the beginning of the mesenteric veins and the commencement of the lacteals.

As the food passes down the intestines, having been previously prepared in the stomach and intestines for absorption, it comes in very close contact with the villi of the intestines and it is here that the nutrition from the food is absorbed through the villi wall into the lacteals, and hence carried to the receptaculum chylii.

The large intestine differs from the small intestine in its greater size, its more fixed position, its sacculated form.

The large intestine in its course describes an arch, which surrounds the convolutions of the small intestines. It commences in the right inguinal region, in a dilated part of the caecum. It ascends through the right lumbar and the right hypochondriac regions to the under surface of the liver, it here takes a bend to the left, the hepatic flexure, and passes transversely across the abdomen on the confines of the epigastric and umbilical regions, to the left hypochondriac region; it then bends again, the splenic flexure, and descends through the left lumbar region to the left inguinal region, where it becomes convoluted and forms the sigmoid flexure; finally it enters the pelvic cavity and descends along the posterior wall to the anus.

The large intestine is supplied by the branches of the inferior mesenteric artery, and the veins are of the same name.

The large intestines are divided into the caecum, colon and rectum.

The Vermiform Appendix.—The appendix is found only in the human, the higher apes, and the wombat, although in certain rodents a somewhat similar arrangement exists. The appendix is a long, narrow, worm shaped, musculo-membranous tube, which starts from the inner side of the posterior wall of the caecum, below and behind the termination of the ileum. It is the seat for a very common disease called appendicitis. It varies from one half to nine inches in length, its average being about three inches. Its diameter is from one eighth to one quarter of an inch.

The ascending colon is smaller than the caecum, with which it is continuous. It passes upward from its commencement at a point corresponding to the ileo-caecal valve, to the under surface of the right lobe of the liver, on the right of the gall bladder, where it is lodged in a shallow depression on the liver; here it bends abruptly inward to the left, forming the hepatic flexure. It is held to the posterior wall of the abdomen by folds of the peritoneum.

The transverse colon is the longest part of the small intestines, passes transversely from the right to the left across the abdomen, opposite the confines of the epigastric and umbilical regions, where it curves downward beneath the lower end of the spleen, forming the splenic flexure. In its course the transverse colon describes an arch, the concavity of which is directed backward toward the vertebral column and a little upward.

This is the most movable part of the colon, only covered by peritoneum and held to the back wall by the folds of the peritoneum. The transverse colon is in relation, by its upper surface with the liver and gall bladder the great curvature of the stomach, and the lower end of the spleen; by its under surface with the small intestines; by its anterior surface with the anterior layers of the great omentum and the abdominal wall; its posterior surface on the right is in relation with the duodenum and on the left it is in contact with the convolutions of the jejunum and ileum.

The descending colon passes downward through the left hypochondriac region and lumbar region along the outer border of the left kidney. At the lower end of the left kidney it turns inward where it terminates in the formation of the sigmoid flexure. The descending colon is held to the back wall by folds of the peritoneum.

The sigmoid flexure, the narrowest part of the colon, is situated in the left inguinal region and communicates with the rectum.

The anus is the terminal opening of the alimentary canal.

In the male it weighs from fifty to sixty ounces, and in the female, from forty to fifty.

It is relatively much larger in the foetus, being about one-eighteenth of the body weight in the foetus, and in the adult, about one-thirty-sixth of the body weight.

Its greatest width is from seven to eight inches, is about twelve inches long, and in its greatest thickness about three inches.

The liver is very soft and is easily lacerated and friable; its color is a dark reddish brown. To obtain a correct idea of its shape, you might compare it to a wedge, the base of which is directed to the right, and thin edge toward the left.

The liver has five surfaces, superior, inferior, anterior, posterior and right lateral.

The liver has five lobes, right and left, caudate, quadrate, and lobus spigelii. It has five ligaments, right and left lateral or triangular, falciform, coronary and round. The liver has five fissures, the umbilical, the fissure of the ductus venosus, the transverse fissure, the fissure for the gall bladder, the fissure for the vena cava. These fissures can be represented by the letter H.

The liver is movable within certain narrow limits. It moves with respiration. On inspiration, it moves down with the diaphragm to a little below the right nipple line. The ligaments do not give the liver much support because they lie relaxed, but it does get its main support from the connective tissue which unites the liver to the diaphragm, the hepatic veins which join the vena cava and also by the intra-abdominal pressure resulting from the tonic contraction of the abdominal muscles.

Also when the abdominal tension is normal, the intestines are driven up, and become a bed for the liver.

The most important function is the secretion of the bile; it is also the excretor of deleterious matter and impurities. It also effects important changes of the blood in its passage through it, for the portal circulation.

The excretory apparatus of the liver consists (a) of the hepatic duct, (b) the gall bladder, (c) cystic duct, (d) the common bile duct.

The hepatic duct is formed by two main trunks nearly of equal size which issue from the liver, one from the right and one from the left lobe. The hepatic duct passes downward and to the right from one to two inches where it is joined at an acute angle with the cystic duct.

The cystic duct is about an inch and a half in length, and passes obliquely downward to the left from the neck of the gall bladder, and joins the hepatic duct.

The common bile duct (ductus communis choledochous) is the common excretory duct of the liver and the gall bladder, and is formed by the union of the cystic and hepatic ducts. It descends to the middle portion of the duodenum, where it unites with the pancreatic duct, the two passing obliquely through the wall of the descending portion of the duodenum. The tissues of the liver are nourished by the blood from the hepatic arteries.

The pancreatic duct is the principal excretory duct of the pancreas. It extends transversely from the left to the right through the substance of the pancreas.

After leaving the body of the pancreas, it unites with the common bile duct of the liver where it empties into the duodenum (first section of the small intestines after leaving the stomach).

The pancreatic duct carries pancreatic juice (a digestive fluid) from the pancreas to the duodenum.

The upper extremity of the kidneys lies on the level of the twelfth dorsal vertebra and the lower extremity on the level of the third lumbar vertebra. Each kidney is four and one-half inches in length, two to two and one-half inches in breadth, a little more than one inch in thickness.

The weight of the kidney in the adult male is from four and one-half to six ounces each. In the adult female the weight would be from four to five and one-half ounces.

Their function is to separate from the blood certain waste products and an excess of water, the combination of which we know as urine. The principal products excreted by the kidneys from the blood along with water are ammonia and urea. The blood is taken to the kidneys by the renal arteries and the renal veins carry it back to the blood circulation.

The urine is then taken from the kidneys by the ureters and conveyed to the urinary bladder.

The functions are as yet unknown. The suprarenal arteries furnish nourishment for the suprarenal capsules.

The uterus is situated in the pelvic cavity between the rectum and the bladder, and is held in position by the lateral and round ligaments on each side. The uterus is about 3 inches in length, 2 inches in breadth and weighs from one to two ounces. It is composed of three coats, external serous, middle muscular, and internal mucous.

The serous coat, derived from the peritoneum, is thin and vascular.

The muscular coat is the chief coat, it is dense, firm, of a grayish color and cuts like cartilage.

The mucous coat is thin, smooth and closely adherent to the muscular coat. It is highly vascular.

The blood supply to the uterus is the uterine arteries which are the posterior branches of the internal iliac arteries, and the ovarian arteries which are branches of the aorta. These break up in capillaries and form a fine network plexus in the coats of the uterus.

The veins are of large size and are the uterine which empty into the internal iliac veins and the ovarian veins. On the right side the ovarian vein empties into the ascending vena cava, and on the left side into the renal vein.

The arteries that supply the prostate are derived from the internal pubic, a branch of the internal iliac.

The veins form a plexus around the gland and communicate with veins which empty into the internal iliac veins. Its function is to secrete an opaque fluid.

The peritoneum is the largest serous membrane in the body. In the male it is a closed sac, a part of which is applied against the abdominal sides, while the remainder is reflected over the contained viscera. In the female it is not a closed sac, since the free extremities of the fallopian tubes open directly into the peritoneal cavity.

The parietal peritoneum is that portion applied against the abdominal sides.

The visceral peritoneum is that portion reflected over the viscera.

The peritoneum consists of two sacs.

The greater sac lines the greater part of the abdominal cavity as almost all of the viscera are covered by it.

The lesser sac is placed behind the stomach. These two sacs communicate with each other by a narrow orifice called the Foramen of Winslow.

The peritoneum, as it covers different organs or sets of organs, receives special names.

The lesser omentum consists of two layers, these split to envelope the stomach.

The greater omentum consists of four layers. Two of these layers extend from the stomach and together with two other layers of the same structure which envelope the transverse colon, form an apron for the intestines.

The mesentery consists of two layers which invests the small intestines. Between the two layers of the mesentery we find the blood vessels, nerves, lacteals, and glands, leading to and from the intestines. The mesentery is fan shaped, and is attached to the second lumbar vertebra. The length of the mesentery fan is about eight inches from commencement to termination at intestine. It extends the whole length of the intestines, which is about twenty feet.

CHAPTER IX. THE VASCULAR SYSTEM.

The system is usually regarded as being composed of two portions, the one consists of organs in which circulate the red fluid which we term blood, and called the blood vascular system, while the organs of the other contain a colorless or white fluid known as lymph or chyle, and is known as the lymphatic circulation.

There is a growing appreciation of the fact, also, that thoroughness in the practice of embalming is worth striving after. Many cases of embalming, no doubt, require a minimum amount of attention, particularly where the body is to be kept but a short time. Where preservation for longer periods is required, as for transportation, or where disease and accident have interfered seriously with the circulation, a more exact knowledge is evidently desirable.

The blood vascular system comprises the heart, which is the central organ of the whole system, and all the blood vessels. This system, with its arteries and veins, permeates the whole body and becomes divided and subdivided at its outer portion into vessels constantly decreasing in size, until those extremely minute vessels, the capillaries, are reached. All the tissues of the body are very rich in these, so that all portions of the body are supplied with blood, which is essential for the nourishment and rebuilding of the tissues. The large vessels which convey blood from the heart are termed arteries, while the vessels which convey the blood back to the heart are termed veins.

For one to properly embalm the human body, it is necessary to understand the way the fluid will circulate through the body, and the only way we can do this is to study the circulation of the blood as it would occur in life.

To facilitate the description of the blood vascular system, it has been divided into six subdivisions as follows:

• (1) Systemic.
• (2) Pulmonary.
• (3) Coronary.
• (4) Portal.
• (5) Foetal.
• (6) Collateral.

The systemic circulation is divided for the sake of convenience into the following:

• (1) The arterial system.
• (2) Capillary.
• (3) The venous system.

The common carotid arteries pass up each side of the neck to a point opposite the Adam's apple, where they, divide into the external carotid, which supplies the muscular tissue of the face, and the internal carotid artery, which goes up through the skull and helps to form the circle of Willis.

The vertebral arteries come off the subclavian arteries on either side and pass upward, winding through the foramen of the vertebrae, until finally arriving inside the cranial cavity, unite to form one artery called the basilar, which helps to form the circle of Willis.

The circle of Willis is situated at the base of the brain and gives off to the front the two anterior cerebral arteries, to the sides the two middle cerebral arteries, and to the back the two posterior cerebral arteries. The two anterior cerebral arteries are connected by the anterior communicating branch, and the middle cerebral artery and the posterior cerebral arteries on each side are connected by the posterior communicating branches. The cerebral arteries terminate in the piamater as a dense capillary network, and from there supply the substance of the brain with nutrition.

The external carotid artery supplies the muscular tissues of the face. The external carotid artery arises from the common carotid artery at about the level of the upper border of the thyroid cartilage—a level which corresponds with the body of the fourth cervicle vertebra. Thence it is directed upward and slightly backward towards the angle of the jaw, where it enters the substance of the parotid gland and continues upward in that structure to just below the root of the zygoma. Here it gives rise to a large branch, the internal maxillary, and is then continued upward over the root of the zygoma upon the side of the skull, this terminal portion of it being termed the superficial temporal artery. The branches of the external carotid artery from below upward are (1) the ascending pharyngeal, (2) the superior thyroid, (3) the lingual, (4) the occipital, (5) the facial or external maxillary, (6) the posterior auricular, (7) the internal maxillary, (8) the superficial temporal.

The arch of the aorta now continues into the thoracic aorta, so called while it is in the thoracic cavity, and after it has passed through the diaphragm becomes the abdominal aorta. At a point opposite the umbilicus or navel the abdominal aorta divides into the two common iliac arteries. Each common iliac artery divides into an internal iliac artery, which supplies the organs of the pelvic cavity, and an external iliac artery, which passes beneath Poupart's ligament. As the artery passes down the leg it is known as the femoral artery, until it passes into the popliteal space, where it is called the popliteal artery. About one inch below the popliteal space the artery divides into the anterior tibial artery, which runs on a straight line down the front and outside of the leg to a point between the big toe and the one next to it, and the posterior tibial artery which passes down the back part of the foreleg between the inside ankle and the heel. The peroneal, a branch of the posterior tibial, passes down the foreleg between the outside ankle and the heel. The anterior tibial artery, as it passes through the instep is known as the large dorsal artery and further on is known as the small dorsal artery. In the foot is the plantar arch, formed by branches of the posterior and anterior tibial arteries, which send out branches to each toe.

Coming off the femoral are the deep femoral and the anastomotica magna arteries, which anastomose and form collateral circulation to the foreleg by means of the recurrent anterior and posterior tibial arteries.

Coming off the subclavian arteries are the superior and inferior mammary arteries, which pass down over the chest wall, anastomose and give collateral circulation to the lower extremities by means of the superior and inferior epigastric arteries, branches of the external iliac and femoral arteries.

The thoracic aorta gives off the intercostal arteries, which supply the ribs, the bronchials which supply the lungs, the esophageal which supplies the esophagus, and the pericardiac which supplies the pericardium.

The abdominal aorta gives off in rotation the coeliac axis, which as a hub in a wheel gives off three spokes, the gastric artery to the stomach, the hepatic to the liver, and the splenic artery to the spleen. The next branch is the phrenic, which supplies the diaphragm, then the suprarenal artery, two or more in number coming off of both the aorta and the renal arteries. The suprarenal arteries supply the suprarenal capsules. The next branch is the superior mesenteric artery, which supplies the small intestines; the next branch is the renal arteries, which supply the kidneys; the next branch is the spermatic or the ovarian arteries, which supply the testes in the male or the ovaries in the female; the inferior mesenteric artery, which supplies the large intestines. Also coming off the aorta at regular intervals are the lumbar arteries, which supply the side walls.

They derive their name from the word capillus (hair). They vary in size from 1-3500 to 1-3000 of an inch, the largest capillaries being those of the skin. These little vessels are so thickly distributed throughout most of the tissues of the body as to make it impossible to insert a cambric needle in the flesh without pricking scores of them.

When we embalm a body the object should be to introduce a sufficient amount of fluid through the arterial system so that these tiny capillaries will be filled. These little vessels are so minute and the walls are so thin that the fluid is immediately taken up into the tissues. If every tissue of the body can be supplied with fluid by means of the capillaries, we would have the ideal, the body would be perfectly embalmed. Let us then not only be arterial embalmers, but, better still, let us be capillary and tissue embalmers.

Capillaries have one wall, which is the continuation of the inner wall of the artery, thus making the capillary so thin that fluid finds its way easily through it into the surrounding tissues.

Some parts of the body are more vascular than others and some tissues of the body, such as the cornea of the eye, the epidermis, cartilage, the substance of the brain, etc., are entirely destitute of capillaries.

The combined area of all the capillaries of the body is many times greater than the combined area of the trunk vessels. If this were not so, the high pressure on the arterial system would break the thin capillary walls and also the greater area allows the blood to circulate more slowly which gives time for the liberation of oxygen to the tissues and for the absorption of carbon dioxide.

The systemic veins receive the impure or carbonized blood from the capillaries and convey it to the right auricle of the heart.

The pulmonic veins receive the pure oxygenized blood from the lungs and convey it to the left auricle of the heart. The pulmonic veins will be taken up and discussed later under the pulmonary circulation.

Systemic veins are divided into superficial and deep veins and sinuses.

The superficial veins are found between the layers of the superficial fascia, just beneath the skin, and communicate with the deep veins by branches which pierce the fascia.

The deep veins are found deeper down, between the muscles, and are surrounded by the deep fascia.

The smaller arteries, such as the radial, brachial, posterior and anterior tibial, and the peroneal arteries, are each accompanied by two veins, one on each side of the artery, which are called venae comites (accompanying veins). The larger arteries, such as the common carotid, the femoral and the iliac, are accompanied by only one vein.

Veins arise from the capillaries, or, rather, from the minute capillary plexus, formed by a massing or blending of the tiny venules. These small vessels unite to form larger trunks, and as they continue toward the heart increase in size until they finally unite to form the ascending and descending venae cavae.

The Sinuses.—The cerebral veins are small vessels that arise from the capillaries of the brain, and terminate in the sinuses of the dura mater. There are many sinuses in the cranial cavity, and differ from the vein, in that the walls are thinner, having only two walls while the veins have three, and they do not have valves. The outer walls of the sinuses of the brain are formed by a division of the dura mater, while the inner wall is the continuation of the inner wall of the vein.

They are of little interest to embalmers, except for the fact that when the brain is injected by any of the so-called needle processes, the fluid is quickly conveyed through these vessels to the tissues of the brain, and that organ is thoroughly preserved.

The vessels starting at the foot are the anterior and posterior tibial veins, which unite just below the knee to form the popliteal vein, in the popliteal space. Another vein starts from the foot and runs into the popliteal vein called the external short saphenous. Starting also at the foot and running into the posterior tibial vein is the peroneal vein.

The popliteal vein after leaving the popliteal space is known as the femoral vein as it passes up the leg, to Poupart's ligament. Another vein, the internal long saphenous, starts at the foot, and runs into the femoral vein about an inch below Poupart's ligament. After passing beneath Poupart's ligament the vessel is called the external iliac. Coming from the organs of the pelvic cavity is the internal iliac, which joins with the external iliac vein to form the common iliac vein. The right and left iliac veins join opposite the umbilicus to form the ascending vena cava. The ascending vena cava passes upward to the right of the vertebral column through the diaphragm and enters the right auricle of the heart by means of the eustachian valve.

In the forearm are the radial veins on the thumb side of the hand, the ulnar veins on the little finger side of the hand, and the median vein just between the radial and ulnar veins. The median vein divides into the median cephalic vein and the median basilic. The median cephalic vein unites with the radial vein to form the cephalic vein, which runs up the back part of the arm and finally empties into the subclavian vein. The median basilic unites with the ulnar vein to form the basilic, which runs up the inner part of the arm between the biceps and triceps muscles. The deep brachial veins or the vena comites, two in number, which follow the brachial artery, run into the basilic vein. When the basilic vein arrives at the axillary space it takes on the name of the axillary vein, and as the vessel passes beneath the subclavian bone, it becomes the subclavian vein. The right and left subclavian veins with the right and left internal jugular veins from each side of the head form the right and left innominate veins, which unite to form the descending vena cava, which runs into the right auricle of the heart.

Starting at the head, the superior longitudinal sinus begins at the fore part of the brain and runs backward between the two hemispheres of the brain and empties into the wine press or Torcular herophili. The inferior longitudinal sinus begins at the fore part of the brain, but rung deeper down in the pia mater between the two hemispheres of the brain, terminates in the straight sinus which empties into the wine press. Beginning at the base of the cerebellum are the two occipital sinuses which run together and terminate in the wine press. After all the blood has been gathered together in the wine press, it leaves by means of the right and left lateral sinuses which pass down as far as the jugular foramen. Beginning at the base of the brain in front are the right and left cavernosus sinuses, which run into the inferior petrosal sinuses, which pass down as far as the jugular foramen, where they join the lateral sinuses to form the right and left internal jugular vein. The superior petrosal sinus is between the lateral sinus and the cavernosus sinus uniting them. Joining the right and left cavernosus sinuses is the circular sinus and joining the right and left inferior petrosal sinuses is the transverse sinus. The right and left internal jugular veins pass down through the jugular foramens and down the neck to where they with the right and left subclavian veins form the right and left innominate veins. The right and left innominate veins unite to form the descending vena cava which empties into the right auricle of the heart.

Beginning in the tissues of the heart are the coronary veins, which terminate in the coronary sinus and then into the right auricle of the heart through the coronary valves.

The azygos system consists of the major azygos vein, which starts at the right external iliac vein and empties into the descending vena cava; the minor azygos vein which starts at the left external iliac vein and empties into the major azygos vein back of the heart; and the tertiary azygos vein, which starts at the left subclavian vein and empties into the minor azygos vein. The azygos veins collect all the blood from the side walls of the body and form a perfect collateral circulation between the superior and inferior caval systems, and thoroughly equalizes the blood pressure all over the body. The major azygos vein receives the following: the right intercostal veins, excepting the first; the azygos minor; the right bronchial vein; the esophageal vein; the pericardiac; and the posterior mediastinal veins. The minor azygos vein receives the following: the tertiary azygos vein; the lower five left intercostal veins; the small left mediastinal veins; the lower left esophageal veins. The tertiary azygos receives the following: the fifth, sixth and sometimes the seventh intercostal veins; the lower end of the lower left superior intercostal vein; and the left bronchial vein. The inferior vena cava receives the following veins: the lumbar veins; the hepatic veins; the phrenic veins; the renal veins; the right suprarenal vein; the right spermatic or ovarian vein. The left spermatic or ovarian vein and the left suprarenal vein empty into the left renal vein.

The pulmonary artery takes its origin from the summit of the right ventricle. It is about two inches in length, and is directed upward, backward and slightly towards the left, and beneath the arch of the aorta it divides into the right and left pulmonary arteries. These end in a system of capillaries in between the air cells of the lungs, where carbon dioxide is thrown off and oxygen taken on.

The pulmonary veins are four in number, two passing from the root of each lung to the posterior surface of the left auricle of the heart. Each vein is formed at the root of the lung by the union of a number of smaller vessels which take origin ultimately from the capillary net work formed from the branches of the pulmonary artery, and to a certain extent from that formed by the bronchial arteries. Each pulmonary vein is about six inches in length.

The coronary sinus is a short venous trunk a little over an inch in length, which occupies the right half of that portion of the auriclo-ventricular groove which lies between the left auricle and ventricle. At the right end it opens into the right auricle, its orifice being guarded by the Thebesian valve.

The portal circulation is formed by the superior mesenteric vein and the splenic vein uniting to form the portal vein. The inferior mesenteric vein runs into the splenic vein; the gastric and cystic veins run into the portal veins. The portal vein ends in capillaries in the liver, where certain important changes take place, namely, the taking out of the bile.

The portal vein and its tributaries are unlike the veins in the general circulation, as there are no valves. Their function in life is to gather up food or nutrition for the blood, and to the embalmer is of no special importance, only to know how this circulation is made up. The vessels that convey blood to the liver in life and the fluid in death are discussed under the liver.

After death, about one-fourth of the blood of the body is to be found in the portal system. This blood can in no way be removed, and this is one of the reasons why the embalmer is not able to draw more blood than he does.

The placenta constitutes, from the third month of intra uterine life, the nutritive and respiratory organ of the foetus. The placenta consists of a maternal portion and a foetal portion. The maternal portion is that portion of the placenta next to the uterine wall of the mother. In this are intervillus blood spaces, which may be regarded as derivations from the eroded maternal blood vessels. In the non-pregnant state the uterus is supplied with branches from the internal iliac artery, which end in capillaries in the wall of the uterus. In the pregnant state the numerous branches of the arteries supplying the uterus do not end as capillaries, but pierce the basal plate of the placenta, where the arterial vessels lose their muscular coat and open directly into the intervillus or intraplacental blood spaces. Maternal capillaries are wanting within the placenta, since they become early replaced by the intervillus spaces. The maternal blood is carried away from these spaces by wide venous channels, forming networks from which proceed the larger venous trunks.

The foetal portion of the placenta is that portion next to the child. Here end the terminal loops of the foetal blood vessels, the blood being conveyed to and from the placenta along the umbilical cord, by the umbilical arteries and vein. Although coming into close relation, the blood streams of the mother and of the child never actually mingle, because of the delicate septum which intervenes. The delicate septum, however, allows the free interchange of gases necessary for the respiratory function as well as the passage of nutritive substances into the foetal circulation.

The umbilical cord connects the body of the foetus with the placenta, and conveys the foetal blood to and from the placenta to the child. This blood is carried by means of two umbilical arteries and one umbilical vein.

The umbilical vein originates by means of capillaries in the placenta, traverses the cord and enters the body of the child at the umbilicus. The umbilical vein now enters the substance of the liver and passes from that organ to the ascending vena cava by means of the ductus venosus. The blood now enters the right auricle of the heart and the eustachian valve is so placed that this blood is thrown directly into the left auricle of the heart, from there into the left ventricle, and out into the aorta to find itself in the general circulation of the child. The blood coming from the upper extremities of the child finds its way into the right auricle of the heart by means of the descending vena cava, thence into the right ventricle, and out into the pulmonary artery. This artery after birth will lead the blood to the lungs, but before birth, in as much as the lungs are not functioning, the lungs can not accommodate this amount of blood, so it passes directly into the arch of the aorta by means of the ductus arteriosus, and thence into the general circulation. The umbilical or hypogastric arteries leave the internal iliacs, pass one on each side of the bladder to the umbilicus, and thence down the cord to the placenta, end there in capillaries, where the blood is now purified, and nourished for its return flow.

In those vessels which have their origin in the wall of the small intestines, the contained fluid has, especially during digestion, a more or less milky appearance, owing to the lymphocytes being loaded with particles of fat which they have taken up from the intestinal contents. On this account, these vessels are usually spoken of as lacteals, although it must be recognized that they are merely portions of the general lymphatic system.

In certain respects the vessels of the system strongly resemble the veins. They arise from a capillary network, their walls have a structure closely resembling that of the veins, they are abundantly supplied with valves, and it may be said that the fluid which they contain flows from the tissues towards the subclavian veins. With these similarities there are combined marked differences. One of the most important of these consists in the fact that the capillaries of the lymphatics are closed and do not communicate with any other set of vessels as the venous capillaries do with the arterial; and another important difference is to be found in the frequent occurrence upon the lymphatic vessels of characteristic enlargements, the so-called lymphatic nodes or glands, quite different from anything occurring in connection with the veins.

Throughout the body spaces of varying size are found, containing a clear, more or less watery fluid, which are called lymph spaces. These spaces do not communicate with the capillaries of the lymphatics, but are in such close relationship with them that the fluid easily finds its way into the lymph capillaries by osmosis, absorption, lymphocytes going out into these spaces and returning filled with the lymph fluid.

The lymphatic capillaries, which are arranged in the form of networks of very different degrees of fineness and complexity, closely resemble in structure the blood capillaries, their walls consisting of a single layer of endothelial cells. They differ from those of the blood vascular system not only in their ultimate branches being closed, but also in their general appearance. They are of greater caliber.

The lymph vessels, which issue from the capillary networks and convey the lymph ultimately to the subclavian veins, have the arrangement closely resembling that of the veins; the larger ones are usually situated alongside and accompany the course of the blood vessels. Just as the veins unite to form larger trunks as they pass from the capillaries toward their termination, so, too, the lymphatics, but the lymphatics present two peculiarities which distinguish them from the veins. They do not anastomose as abundantly as veins and there is not the same proportional increase in the size of the lymphatic vessel. The left trunk or thoracic duct is much larger than the right, beginning in the abdominal region and traversing the entire length of the thorax to reach its destination. It receives all the lymph returned from the lower limbs, the pelvic walls and viscera, the abdominal walls and viscera, the lower part of the right half and the whole of the left half of the thoracic viscera, the left side of the neck and head, and the left arm. The other trunk, the right lymphatic duct, is very short and sometimes wanting. It receives the lymph from the upper part of the right side of the thoracic wall, from the right half of the thoracic viscera and the upper surface of the liver, the right side of the neck and head, and from the right arm. The structure of the larger lymphatic vessels is similar to the veins, but, as a rule, their walls are thinner than those of the veins of corresponding caliber and their valves are more numerous. The walls of the most robust trunks, particularly those of the thoracic duct, consist of three coats. From within outward these are: (a) the intima, composed of the endothelial lining and the fibro-subendothelial layer; (b) the media, made up of involuntary muscle interspersed with fibro-elastic tissue; and (c) the adventitia, consisting of fibro-elastic tissue and longitudinal bundles of involuntary muscle.

Lymphatic nodes are scattered along the course of the lymphatic vessels, found in various regions of the body as elliptical flattened nodules of varying size. The embalmer will meet with these in the axillary and inguinal regions, or when he is raising the axillary or femoral arteries.