A muscle that originates from the dorsal surface of the inferior angle of the scapula and inserts into the medial border of the bicipital groove in the humerus. Innervated by the lower subscapular nerve and/or thoracodorsal nerve. Adducts, internally rotates, and extends the arm when the scapula is fixed by other muscles. Protracts the scapula when the humerus is in a fixed position.