Brachial fascia

The brachial fascia is a dense, sleeve-like fibrous sheath encasing the muscles of the upper arm from the shoulder to the elbow. It is not an isolated structure but is extensively reinforced and continuous with fascia from the pectoral girdle muscles (pectoral, latissimus dorsi, deltoid, infraspinatus fasciae), forming a continuous myofascial chain that aids force transmission across the upper limb.

The brachial fascia is vital for compartmentalization, creating distinct anterior and posterior muscle groups in the arm via the medial and lateral intermuscular septa. These septa also serve as conduits for neurovascular structures; for example, the radial nerve and radial collateral artery perforate the lateral septum, while the ulnar nerve and associated arteries perforate the medial septum.

Distally, at the elbow, the brachial fascia is attached to the humeral epicondyles and the olecranon of the ulna, completing the muscular compartments, and becomes continuous with the antebrachial fascia.

Overall function

More broadly, the brachial fascia, as part of the upper limb's extensive fascial network, not only compartmentalizes but also provides crucial pathways for neurovascular structures, contributes to proprioception, and aids in the efficient transmission of force.