ELBOW JOINT. 



139 



belonging to the infra- spinatus muscle ; and it moreover forms a 

 sheath around that portion of the tendon of the biceps, which is in- 

 cluded within the joint. 



The muscles immediately surrounding the shoulder joint are the 

 subscapularis, supra-spinatus, infra-spinatus, teres minor, long head 

 of the triceps and deltoid ; the long tendon of the biceps is within 

 the capsular ligament. 



Actions. The shoulder joint is capable of 

 every variety of motion, viz. of movement Fig. 66.* 



forwards and backwards, of abduction and ad- 

 duction, of circumduction and rotation. 



5. Elbow Joint. The elbow is a ginglymoid 

 articulation ; its ligaments are four in num- 

 ber- 

 Anterior, 

 Posterior, 

 Internal lateral, 

 External lateral. 



The anterior ligament is a broad and thin 

 membranous layer, descending from the an- 

 terior surface of the humerus, immediately 

 above the joint, to the coronoid process of 

 the ulna and orbicular ligament. On each 

 side it is connected with the lateral ligaments. 

 It is composed of fibres which pass in three 

 different directions, vertical, transverse, and 

 oblique, the latter being extended from within 

 outwards to the orbicular ligament, into which 

 they are attached inferiorly. This ligament is 

 covered in by the brachialis anticus muscle. 



The posterior ligament is a broad and loose 

 layer passing between the posterior surface of 

 the humerus and the anterior surface of the 

 base of the olecranon, and connected at each 

 side with the lateral ligaments. It is covered 

 in by the tendon of the triceps. 



The internal lateral Ligament is a thick tri- 

 angular layer, attached above, by its apex, to 

 the internal condyle of the humerus ; and be- 

 low, by its expanded border, to the margin of the greater sigmoid 

 cavity of the ulna, extending from the coronoid process to the olecra- 

 non. At its insertion it is intermingled with some transverse fibres. 



* An external view of the elbow joint. 1. The humerus. 2. The ulna. 3. 

 The radius. 4. The external lateral ligament inserted inferiorly into (5) the 

 orbicular ligament. 6. The posterior extremity of the orbicular ligament, 

 spreading out at its insertion into the ulna. 7. The anterior ligament, scarcely 

 apparent in this view of the articulation. 8. The posterior ligament, thrown 

 into folds by the extension of the joint. 



