Corpus: Medial intermuscular septum of arm

The medial intermuscular septum of arm is a connective tissue fascial layer on the medial side of the upper arm.

The medial intermuscular septum of arm originates from the medial edge of the humerus between the distal part of the lesser tubercle's crest and the medial epicondyle. From here, it extends to the underside of the brachial fascia. The medial intermuscular septum of arm is somewhat thicker than the lateral intermuscular septum of the arm located on the opposite side. It serves as the origin for the following muscles:

• triceps brachii muscle
• brachialis muscle

The septum is penetrated by the ulnar nerve, the superior ulnar collateral artery, and the posterior branch of the inferior ulnar collateral artery.