A long, round muscle with tapering ends, largely intersected with bands of tendinous tissue.

Origin. - From a bony projection (coracoid process) at the lower and front part of the blade-bone.

Insertion. - To a roughened bony eminence on the inner and upper part of the radius or lower arm, and by a band of fibrous tissue to the ensheathing fascia of the arm. The tendon of this muscle passes over the front of the shoulder-joint and then over the "bicipital groove" on the summit of the humerus.

Between the tendon and the groove there is a large synovial bursa to facilitate the play of the one over the other.

Action. - It flexes the fore-arm on the humerus, and by tightening up the investing fascia gives support to the muscles in this region.