80S 



THE ARTICULATIONS, OR JOINTS 



tissue which bridges across the notch between the olecranon and coronoid pro-, 

 cesses. 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 muscle. 



The external lateral ligament (ligamentum collaterale radiale) (Fig. 249) is a 

 short and narrow 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 posterior 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. 



Synovial Membrane (Fig. 250). 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 (recessus saccifonnis) 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 humeroradial, the other the 

 humeroulnar. 



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. The two last-named pads are pressed 

 into their respective fossa? during extension. 



The muscles (Fig. 251) 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. 



The arteries supplying the joint are derived 

 from the anastomosis between the superior pro- 

 funda, inferior profunda, and anastomotica magna, 

 branches of the brachial, with the anterior, pos- 

 terior, and interosseous recurrent branches of the 

 ulnar and the recurrent branch of the radial. 

 These vessels form a complete chain of anasto- 

 moses around the joint. 



The nerves are derived from the ulnar as it 

 passes between the internal condyle and the olec- 

 ranon; a filament from the musculocutaneous, and 

 two filaments from the median. 



Bursse. The olecranon bursa (bursa subcutanea olecrani) is placed between the olecranon 

 process and the cutaneous surface. A bursa exists between the tendon of the Biceps brachii 

 and the tubercle of the radius (bursa bicipitoradialis) ; another between the Triceps tendon and 

 the olecranon process (bursa subtendinea olecrani) ; a third between the cutaneous surface and the 

 external condyle (bursa subcutanea epicondyli humeri lateralis); a fourth between the cutaneous 

 surface and the internal condyle (bursa subcutanea epicondyli humeri medialis); and a fifth 

 internal to the Triceps tendon at its insertion on the olecranon (bursa intratcndinca olecrani). 



Movements. The elbow-joint comprises three different portions viz., the joint between 

 the ulna and humerus, that between the head of the radius and the humerus, and the superior 

 radioulnar articulation, described below. All these articular surfaces are invested by a common 

 synovial membrane, and the movements of the whole joint should be studied together. The com- 

 bination of the movements of flexion and extension of the forearm with those of pronation and 

 supination of the hand, which is insured by the two being performed at the same joint, is essential 

 to the accuracy of the various minute movements of the hand. 



The portion of the joint between the ulna and humerus is a simple hinge-joint, and allows 



FIG. 251. Sagittal section of the right elbow- 

 joint, taken somewhat obliquely and seen from 

 the radial aspect. (After Braune.) 



