Muscle · Upper arm

Coracobrachialis

Musculus coracobrachialis

A long slim muscle running down the inner side of the upper arm, from the hook of bone at the front of the shoulder blade to the middle of the humerus. It shares its origin with the short head of biceps, but where biceps carries on past the elbow, this one stops halfway down the arm — so it acts on the shoulder only. It draws the arm forward and inward toward the body's midline, and it holds the head of the humerus into its socket as it does. The detail that makes it a landmark rather than a footnote is that the musculocutaneous nerve pierces straight through its belly on its way to the elbow flexors.