The Probert Encyclopaedia of Medicine

TRICEPS

The triceps brachii (three-headed muscle) lies at the upper portion of the inside of the arm. It is the main extensor of the arm and is made up of three teardrop shaped heads: the long head, the lateral head, and the medial head. When working with other nearby muscles it can also move the shoulder, since its upper ends are attached to the scapula. The long head (caput longum), the largest of the three heads, originates from the scapula just below the rounded socket of the shoulder joint, and extends almost three-fourths of the way toward the front of the arm. The lateral head (caput laterale) originates below the greater tubercle of the humerus and lies on the back and side of the upper arm. The medial head (caput mediale) originates below the radial groove and curves around the back of the humerus and is mostly covered by the long head. The lower end of the muscle inserts in the flattened end of the ulna (olecranon). This muscle is innervated by the radial nerve and supplied by muscular branches of the brachial artery. The triceps brachii extend the forearm at the elbow joint. It works with the biceps brachii to control the up and down movement of the forearm.
Research Triceps