(n.) A muscle having three heads; specif., the great extensor of the forearm, arising by three heads and inserted into the olecranon at the elbow.

adductor arm buccinator elbow forearm gemellus gluteus maximus infraspinatus intercostal latissimus dorsi levator masseter mentalis mylohyoid nasalis oblique occipitalis omohyoid pectineus pectoralis peroneus sphincter tensor trapezius triceps upper arm wrist