Fasciae of upper limb

The fasciae of upper limb and related fibrous structures form a continuous, interconnected network that compartmentalizes muscles, supports neurovascular structures, and transmits mechanical forces. These include:

• Axillary fascia (This is the deep fascia covering the floor of the axilla or armpit, forming the base of the axillary pyramid. It is continuous with the pectoral and brachial fasciae)

• Supraspinatus fascia (A strong, dense fascia covering the supraspinatus muscle within the supraspinous fossa of the scapula, completing the osteofascial compartment for the muscle)

• Infraspinatus fascia (A thick, fibrous layer covering the infraspinatus muscle in the infraspinous fossa, providing an origin for some muscle fibers)

• Deltoid fascia (The deep fascia covering the deltoid muscle, and is continuous with the nearby axillary and pectoral fasciae)

• Brachial fascia (The deep fascia of the arm, forming a strong, sleeve-like covering that encloses the muscles and is continuous with the deltoid, pectoral, and axillary fasciae proximally, and the antebrachial fascia distally)

• Medial intermuscular septum of arm (A strong fibrous partition extending from the brachial fascia to the medial supracondylar ridge and medial epicondyle of the humerus, separating the anterior and posterior compartments of the arm)

• Lateral intermuscular septum of arm (A similar fibrous partition extending from the brachial fascia to the lateral supracondylar ridge and lateral epicondyle of the humerus, also separating the anterior and posterior compartments)

• Antebrachial fascia (The deep fascia of the forearm, forming a dense, investing sleeve that encloses the forearm muscles and creates various intermuscular septa to form distinct compartments)

• Dorsal fascia of hand (A thin, loose layer of deep fascia on the back of the hand, covering the extensor tendons and continuous with the antebrachial fascia proximally)

• Superficial transverse metacarpal ligament (A fibrous band located superficially in the palm, connecting the skin of the web spaces and preventing excessive spreading of the fingers)

• Palmar aponeurosis (A dense, triangular sheet of deep fascia in the central palm, tightly adherent to the skin, protecting underlying structures, and providing attachment for some intrinsic hand muscles)

• Flexor retinaculum of wrist (A strong, transverse fibrous band spanning across the anterior aspect of the wrist, connecting the carpal bones to form the roof of an osteofascial canal called the carpal tunnel. The tunnel transmits flexor tendons and the median nerve into the hand)

• Ulnar canal (a.k.a. the Guyon's canal) (A narrow fibro-osseous tunnel at the ulnar side of the wrist, formed by the pisiform, hook of hamate, and overlying palmar carpal ligament, transmitting the ulnar nerve and artery into the hand)

• Tendinous chiasm (Refers to the point where the tendons of the flexor digitorum superficialis bifurcate to allow the passage of the flexor digitorum profundus tendons through them, typically occurring at the level of the proximal phalanx)

• Flexor mechanism of fingers

This fascial system is highly innervated, especially in the hand, and plays a key role in proprioception, compartmentalization, and force transmission throughout the upper limb.