This muscle makes up the distal segment of the brachiocephalicus. It originates at the clavicular tendon but functionally, from the head and neck through the cleidocervicalis. It inserts at the distal end of the cranial border of the humerus, where it lies between the biceps brachii medially and the brachialis laterally. The muscle partly covers the pectoral muscles at their insertions. In conjunction with the cleidocervicalis, it advances the limb, extends the shoulder and causes lateral movement of the head and neck. [ MURDOCH:376 ]