A narrow muscle tapering towards the extremities, and situated on the internal face of the shoulder.

Origin. - From the posterior or dorsal angle of the scapula, and from the fascia underlying the subscapularis in front of it.

Insertion. - With the latissimus dorsi, into a small tubercle on the inner surface of the humerus.

Action. - To flex the humerus on the shoulder and rotate it inwards.