Henry Gray (18251861). Anatomy of the Human Body. 1918.
The Posterior Ligament (Fig. 330).This posterior ligament is thin and membranous, and consists of transverse and oblique fibers. Above, it is attached to the humerus immediately behind the capitulum and close to the medial margin of the trochlea, to the margins of the olecranon fossa, and to the back of the lateral epicondyle some little distance from the trochlea. Below, it is fixed to the upper and lateral margins of the olecranon, to the posterior part of the annular ligament, and to the ulna behind the radial notch. The transverse fibers form a strong band which bridges across the olecranon fossa; under cover of this band a pouch of synovial membrane and a pad of fat project into the upper part of the fossa when the joint is extended. In the fat are a few scattered fibrous bundles, which pass from the deep surface of the transverse band to the upper part of the fossa. This ligament is in relation, behind, with the tendon of the Triceps brachii and the Anconæus.
The Ulnar Collateral Ligament (ligamentum collaterale ulnare; internal lateral ligament) (Fig. 329).This ligament is a thick triangular band consisting of two portions, an anterior and posterior united by a thinner intermediate portion. The anterior portion, directed obliquely forward, is attached, above, by its apex, to the front part of the medial epicondyle of the humerus; and, below, by its broad base to the medial margin of the coronoid process. The posterior portion, also of triangular form, is attached, above, by its apex, to the lower and back part of the medial epicondyle; below, to the medial margin of the olecranon. Between these two bands a few intermediate fibers descend from the medial epicondyle to blend with a transverse band which bridges across the notch between the olecranon and the coronoid process. This ligament is in relation with the Triceps brachii and Flexor carpi ulnaris and the ulnar nerve, and gives origin to part of the Flexor digitorum sublimis.
The Radial Collateral Ligament (ligamentum collaterale radiale; external lateral ligament) (Fig. 330).This ligament is a short and narrow fibrous band, less distinct than the ulnar collateral, attached, above, to a depression below the lateral epicondyle of the humerus; below, to the annular ligament, some of its most posterior fibers passing over that ligament, to be inserted into the lateral margin of the ulna. It is intimately blended with the tendon of origin of the Supinator.
Synovial Membrane (Figs. 331, 332).The synovial membrane is very extensive. It extends from the margin of the articular surface of the humerus, and lines the coronoid, radial and olecranon fossæ on that bone; it is reflected over the deep surface of the capsule and forms a pouch between the radial notch, the deep surface of the annular ligament, and the circumference of the head of the radius. Projecting between the radius and ulna into the cavity is a crescentic fold of synovial membrane, suggesting the division of the joint into two; one the humeroradial, the other the humeroulnar.
Between the capsule and the synovial membrane are three masses of fat: the largest, over the olecranon fossa, is pressed into the fossa by the Triceps brachii during the flexion; the second, over the coronoid fossa, and the third, over the radial fossa, are pressed by the Brachialis into their respective fossæ during extension.
The muscles in relation with the joint are, in front, the Brachialis; behind, the Triceps brachii and Anconæus; laterally, the Supinator, and the common tendon of origin of the Extensor muscles; medially, the common tendon of origin of the Flexor muscles, and the Flexor carpi ulnaris.
The arteries supplying the joint are derived from the anastomosis between the profunda and the superior and inferior ulnar collateral branches of the brachial, with the anterior, posterior, and interosseous recurrent branches of the ulnar, and the recurrent branch of the radial. These vessels form a complete anastomotic network around the joint.
The nerves of the joint are a twig from the ulnar, as it passes between the medial condyle and the olecranon; a filament from the musculocutaneous, and two from the median.
Movements.The elbow-joint comprises three different portionsviz., the joint between the ulna and humerus, that between the head of the radius and the humerus, and the proximal radioulnar articulation, described below. All these articular surfaces are enveloped by a common synovial membrane, and the movements of the whole joint should be studied together. The combination of the movements of flexion and extension of the forearm with those of pronation and supination of the hand, which is ensured by the two being performed at the same joint, is essential to the accuracy of the various minute movements of the hand.