256 THE ARTICULATIONS. 



fibres pass obliquely from the inner condyle of the humerus outward to the 

 orbicular ligament. The middle fibres, vertical in direction, pass from the upper 

 part of the coronoid depression and become partly blended with the preceding, but 

 mainly inserted into the anterior surface of the coronoid process. The deep or 

 transverse set intersects these at right angles. This ligament is in relation, in 

 front, with the Brachialis ariticus, except at its outermost part ; behind, with the 

 synovial membrane. 



The Posterior Ligament (Fig. 172) is a thin and loose membranous fold, attached, 

 above, to the lower end of the humerus, above and at the sides of the olecranon 

 fossa ; below, to the groove on the upper and outer surfaces of the olecranon. The 

 superficial or transverse fibres pass between the adjacent margins of the olecranon 

 fossa. The deeper portion consists of vertical fibres, some of which, thin arid 

 weak, pass from the upper part of the olecranon fossa to the margin of the ole- 

 cranon ; others, thicker and stronger, pass from the back of the capitellum of the 

 humerus to the posterior border of the lesser sigmoid cavity of the ulna. This 

 ligament is in relation, behind, Avith the tendon of the Triceps and the Anconeus ; 

 in front, with the synovial membrane. 



The Internal Lateral Ligament (Fig. 171) is a thick triangular band consisting 

 of two portions, an anterior and posterior, united by a thinner intermediate por- 

 tion. The anterior portion, directed obliquely fonvard, is attached, above, by its 

 apex, to the front part of the internal condyle of the humerus ; and, below, by its 

 broad base, to the inner 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 internal condyle ; below, to the inner margin of the olecranon. 

 Between these two bands a few intermediate fibres descend from the internal con- 

 dyle to blend with a transverse band of ligamentous tissue which bridges across 

 the notch between the olecranon and coronoid processes. This ligament is in 

 relation, internally, with the Triceps and Flexor carpi ulnaris muscles and the 

 ulnar nerve, and gives origin to part of the Flexor sublimis digitorum. 



The External Lateral Ligament (Fig. 172) is a short and narrow r fibrous band, 

 less distinct than the internal, attached, above, to a depression below .the external 

 condyle of the humerus ; below, to the orbicular ligament, some of its most pos- 

 terior fibres passing over that ligament, to be inserted into the outer margin of the 

 ulna. This ligament is intimately blended with the tendon of origin of the 

 Supinator brevis muscle. 



The Synovial Membrane is very extensive. It covers the margin of the 

 articular surface of the humerus, and lines the coronoid and olecranon fossae on 

 that bone; from these points it is reflected over the anterior, posterior, and 

 lateral ligaments, and forms a pouch between the lesser sigmoid cavity, the 

 internal surface of the orbicular ligament, and the circumference of the head of 

 the radius. Projecting into the cavity is a crescentic fold of synovial membrane, 

 between the radius and ulna, suggesting the division of the joint into two: one the 

 humero-radial, the other the humero-ulnar. 



Between the capsular ligament and the synovial membrane are three masses 

 of fat ; one, the largest, above the olecranon fossa, which is pressed into the fossa by 

 the triceps during flexion ; a second, over the coronoid fossa ; and a third, over 

 the radial fossa. These are pressed into their respective fossae during extension. 



The Muscles in relation with the joint are, in front, the Brachialis anticus ; 

 behind, the Triceps and Anconeus; externally, the Supinator brevis and the 

 common tendon of origin of the Extensor muscles; internally, the common 

 tendon of origin of the Flexor muscles, and the Flexor carpi ulnaris, with the 

 ulnar nerve (Fig. 173). 



The Arteries supplying the joint are derived from the anastomosis between the 

 superior profunda, inferior profunda, and anastomotica magna arteries, 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 

 chain of inosculation around the joint. 



