Fascia of the shoulder girdle and upper arm

The superficial fascia of the upper limb is part of the superficial fascia that covers the entire body.

The fascia of the supraspinatus muscle is thick (up to 2 mm), dense, at the top it is fused with the transverse ligament of the scapula, with the coracoid process and the capsule of the shoulder joint. Between the supraspinatus muscle and the bottom of the supraspinatus fossa there is a thin layer of tissue in which the suprascapular nerve and suprascapular artery with the veins adjacent to it are located.

The infraspinatus fascia is also dense and has a tendinous structure. This fascia forms a fascial sheath for the teres minor muscle and continues onto the teres major muscle. In the loose tissue under the infraspinatus muscle is the artery that encircles the scapula. At the base of the acromial process, the supraspinatus and infraspinatus fascial sheaths communicate with each other (along the course of the blood vessels and nerves passing into the infraspinatus fossa).

In the deltoid region, the superficial fascia has a fibrous structure, especially over the acromial part of the deltoid muscle.

The deltoid fascia (fascia deltoidea) forms a fascial sheath for the deltoid muscle. Connective tissue septa extend from this fascia into the muscle, especially at the borders of the scapular, acromial and clavicular parts. Some of the fibers of the deltoid muscle begin from the septa. The subdeltoid cellular space, which corresponds mainly to the acromial part of the muscle, continues downwards to the point of attachment of the deltoid muscle to the humerus. The subdeltoid space contains the tendon of the long head of the biceps brachii, branches of the axillary nerve and the posterior artery that circumflexes the humerus, which penetrate into the subdeltoid space through the quadrilateral opening. The anterior artery and vein that circumflex the humerus also pass through the subdeltoid space. The deltoid fascia continues laterally and downwards into the fascia of the shoulder, in front into the fascia of the chest, and fuses with the infraspinatus fascia behind.

The axillary fascia (fiscia axillaris) is thin, loose, has numerous openings through which cutaneous nerves, blood and lymphatic vessels pass. At the borders of the axillary region, the fascia thickens and is fused with the fascia of neighboring areas - it passes into the fascia of the chest and the fascia of the shoulder.

The brachial fascia (fascia brachialis) forms two osteofascial compartments (anterior and posterior), which are separated from each other by the medial and lateral intermuscular septa (septum intermusculare brachii mediale et septum intermusculare brachii laterale). These septa extend from the brachial fascia and are attached to the humerus. In the anterior osteofascial compartment, the muscles are arranged in two layers. The biceps brachii is located more superficially, and underneath it lie the coracobrachialis (proximally) and brachialis (distal) muscles. Both muscle layers are separated by a deep leaflet of the brachial fascia, under which the musculocutaneous nerve passes.

In the medial groove of the biceps brachii there passes a vascular-nerve bundle formed by the median nerve, brachial artery and veins. On the posterior surface of the arm, the proper fascia forms the sheath of the triceps brachii muscle, in front of which the posterior vascular-nerve bundle passes in the radial nerve canal. The radial nerve canal, or brachial muscle canal (canalis nervi radialis, s. canalis humeromuscularis), is located between the posterior surface of the humerus and the triceps muscle. The upper (entrance) opening of the canal, located at the level of the border between the upper and middle thirds of the body of the humerus, is limited on the medial side by the humerus and two heads (lateral and medial) of the triceps brachii muscle. The lower (exit) opening of the canal is located at the level of the border between the middle and lower thirds of the humerus on the lateral side of the arm, between the brachialis and brachioradialis muscles. The radial nerve passes through this canal together with the deep artery and veins of the arm.

In the posterior elbow region, two grooves are visible on the sides of the olecranon. Above the olecranon itself, under the skin, is the subcutaneous olecranon bursa. Under the tendon of the triceps brachii, which is attached to the upper posterior surface of the olecranon, is the tendon bursa of the same name. On the posterior surface of the elbow joint, the fascia is thickened due to the tendon fibers of the triceps brachii intertwined with it. The fascia is firmly fused with the posterior edge of the ulna, as well as with the medial and lateral epicondyles of the humerus. Under the fascia, in the posterior medial olecranon groove, in the bone-fibrous canal (narrow gap) formed by the posterior surface of the medial epicondyle of the humerus, the olecranon process and the fascia, the ulnar nerve passes.

In the anterior elbow region, the cubital fossa (fossa cubitalis) is visible, the bottom and upper border of which are limited by the brachioradialis muscle (from the lateral side) and the pronator teres (from the medial side). In the cubital fossa, the lateral cubital groove (sulcus bicipitalis lateralis, s. radialis) is distinguished, limited externally by the brachioradialis muscle, from the medial side - by the brachialis muscle, and the medial cubital groove (sulcus bicipitalis medialis, s. ulnaris), located between the pronator teres (laterally) and the brachialis muscle (medially). The lateral and medial saphenous veins are located in the subcutaneous tissue. The brachial artery passes under the aponeurosis of the biceps brachii muscle, to which two veins of the same name and the median nerve are adjacent. In the anterior elbow region, above the biceps tendon, the fascia is thin. Medial to this tendon, the fascia thickens as it is reinforced by the fibers of the aponeurosis of the biceps brachii.

Along the lines of the medial and lateral ulnar grooves, the medial and lateral intermuscular septa extend deep from the fascia and are attached to the epicondyles of the humerus and to the capsule of the elbow joint. As a result, 3 fascial muscle beds (cases) are formed in the anterior elbow region under the fascia. In the medial bed, the most superficial are the pronator teres, flexor carpi radialis, palmaris longus, and flexor carpi ulnaris. Under these muscles in the second layer is the flexor digitorum superficialis, in the lateral fascial bed is the brachioradialis muscle, and under it is the supinator. In the middle fascial bed (between the two ulnar grooves) are the distal part of the biceps brachii and its tendon, and under them is the ulnar muscle. Between the indicated muscle groups in the splits of the muscle partitions, the medial and lateral vascular-nerve bundles pass on the forearm. Distal to the elbow joint, the medial and lateral fascial intermuscular partitions approach each other and join with each other, forming the anterior radial intermuscular partition of the forearm.

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