266 The Elboiv Joint 



Neither is the external lateral ligament nor any other part of the 

 capsule of the joint, nor of the deep fascia, connected with the upper 

 end of the radius, for there must be no check to its rotation. 



The capsule of the elbow-joint consists of the anterior, posterior, 

 and lateral ligaments in conjunction with all those intermediate fibres 

 which connect them with each other. 



The synovial membrane lines the capsule and is reflected over 

 the articular surfaces of humerus, ulna, and radius ; it also lines the 

 lesser sigmoid cavity of the ulna, and the orbicular ligament, and is 

 wrapped around the neck of radius. 



Relations of the elbow-joint. In front is the brachialis anticus, 

 and more anteriorly are the tendon of the biceps, the brachial artery, 

 and the median nerve. Behind are the triceps and anconeus. In- 

 fernally are the origin of the pronators and flexors, the ulnar nerve, 

 and the inferior profunda artery. Externally are the supinator brevis 

 and the origin of the extensors, and towards the front are the superior 

 profunda artery and the musculo-spiral nerve dividing into the radial 

 and posterior interosseous. 



The superior radio -ulnar joint is formed by the head of the radius 

 and the lesser sigmoid cavity of the ulna, the only movements allowed 

 at that joint being pronation and supination. The orbicular binds the 

 head and neck of the radius close against the ulna, and, forming the 

 medium of attachment for the anterior and the external lateral liga- 

 ments of the elbow-joint, allows free pronation and supination. The 

 synovial membrane is a prolongation from that of the elbows-joint. 



Supply. Branches of artery come from the superior and in- 

 ferior profunda ; the anastomotica magna ; the anterior and posterior 

 ulnar recurrents ; and from the radial and the interosseous rccurrcnts. 

 Nerve-twigs come from the ulnar and the musculo-cutaneous. 



Dislocations at the elbow-joint. In dislocation of both bones 

 backwards the olecranon process stands out like a heel behind the 

 albow, and the button-head of the radius can be made out through the 

 skin behind the external condyle. The coronoid process, if not broken 

 off, sinks into the olecranon fossa ; the brachialis anticus and biceps 

 are stretched round the lower end of the humerus, and the front of the 

 fore-arm is strangely short. The bones of the fore-arm being so firmly 

 fixed in their new position, flexion, extension, and rotation are impos- 

 sible, and on attempting to flex the joint the appearance becomes still 

 more characteristic. 



To reduce this dislocation, the surgeon thrusts his knee into the 

 front of the elbow, steadies the humerus with one hand, and pulls on 

 the radius and ulna by grasping them above the wrist, and as he pulls 

 he flexes the fore-arm round his knee, so as to unhitch the coronoid 

 process. Thus the bones slip again into their position ; and there they 

 securely remain unless the coronoid process happen to be broken off, 

 in which case the luxation may recur. This recurrence suggests 



