Corpus: Lateral Intermuscular Septum of Arm

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

The lateral intermuscular septum of arm originates from the lateral edge of the humerus between the crest of the greater tubercle and the lateral epicondyle. It is less developed than the medial intermuscular septum of the arm, which runs on the opposite side of the upper arm. From here, it extends to the underside of the brachial fascia. It serves as the origin for the following muscles:

• triceps brachii muscle
• brachialis muscle
• brachioradialis muscle
• extensor carpi radialis longus muscle

The septum is penetrated by the radial nerve and the deep artery of the arm (arteria profunda brachii).