LIGAMENTS OF ELBOW. 



293 



Fig. 90. 



elbow, the brachialis anticus must be taken away from the front, and the 

 triceps from the back of the joint. The muscles connected with the outer 

 and inner condyles of the humerus, as well as the supinator brevis and 

 the flexor profundus, are to be removed. With a little cleaning the four 

 ligaments anterior, posterior, and two lateral will come into view. 



The interosseous membrane between the bones of the forearm will be 

 prepared by the removal of the muscles on both surfaces. 



THE ELBOW JOINT (fig. 90). In this articulation the lower end of the 

 humerus is received into the hollow of the ulna, so as to produce a hinge- 

 like arrangement ; and the upper end of the radius assists to form part of 

 the joint. Where the bones touch the surfaces 

 are covered with cartilage, and their articular ends 

 are kept in place by the following ligaments : 



The external lateral ligament is a roundish fas- 

 ciculus, which is attached by one end to the outer 

 condyle of the humerus, and by the other to the 

 orbicular ligament around the head of the radius. 

 A few of the posterior fibres pass backwards to the 

 external margin of the ulna. 



The internal lateral ligament is triangular in 

 shape. It is pointed at its upper extremity, and 

 is connected to the inner condyle of the humerus. 

 The fibres diverge, and are inserted in this way: 

 The anterior, which are the strongest, are fixed to 

 the edge of the coronoid process ; the posterior are 

 attached to the side of the olecranon ; whilst a few 

 middle fibres join a transverse ligamentous band 

 over the notch between the olecranon and the coro- 

 noid process. The ulnar nerve is in contact with 

 the ligament; and vessels enter the joint by an 

 aperture beneath the transverse band. 



The anterior ligament is thin, and its fibres are 

 separated by intervals in which masses of fat are 

 lodged. By its upper edge the ligament is inserted 

 into the front of the humerus, and by its lower 

 into the front of the coronoid process and the or- 

 bicular ligament. The brachialis anticus muscle 

 covers it. 



The posterior ligament is much thinner and 

 looser than the anterior, and is covered completely 

 by the triceps muscle. Superiorly it is attached 

 to the humerus above the fossa for the olecranon ; 

 and inferiorly it is inserted into the olecranon. 

 Some few fibres are transverse between the mar- 

 gins of the fossa before mentioned. 



Dissection. Open the joint by an incision 

 across the front near the humerus, and disarticu- 

 late the bones, in order that the articular surfaces 

 may be seen. 



The synovial membrane of the joint can be traced from one bone to 

 another along the inner surface of the connecting ligaments. It projects 

 between the radius and the orbicular ligament, and serves for the articu- 

 lation of the head of that bone with the small sigmoid cavity of the ulna. 



THE LirtAMExrs OF THE EL- 

 BOW JorNT, AND THE 



SHAFT OF THE RADIUS 

 AND ULNA (Bourgery and 

 Jacob). 



1. Capsule of the elbow 



joint. 



2. Oblique ligament 



3. Interosseous ligament. 



4. Aperture for bloodves- 



sels. 



5. Tendon of the biceps. 



