Relationship of arteries and nerves of arm to humerus and compartments of arm

The radial nerve and accompanying profunda brachii artery wind posteriorly around, and directly on the surface of, the humerus in the radial groove. The radial nerve and radial collateral artery then pierce the lateral intermuscular septum to enter the anterior compartment. The ulnar nerve pierces the medial intermuscular septum to enter the posterior compartment and then lies in the groove for the ulnar nerve on the posterior aspect of the medial epicondyle of the humerus. The median nerve and brachial artery descend in the arm to the medial side of the cubital fossa, where it is well protected and rarely injured.