LIGAMENTS OF THE ELBOW-JOINT. 



95 



Potation. There are two kinds of rotatory movement, viz., in Rotation 

 ami out ; and in each the humerus revolves around an axis passing 

 from the centre of the head through the shaft to the lower end of 

 tin- bone. 



In rotation in, the great tuberosity moves forwards and inwards, in, and 

 tlie head of the bone glides backwards in the glenoid cavity, 

 and the hinder part of the capsule is 



rendered tense. In rotation out, the ^ out. 



movements of the parts of the humerus 

 are reversed, and the front of the cap- 

 sule is stretched. The movements are 

 stopped by the tightening of the cap- 

 sule, assisted by the muscles on the back 

 and front of the joint respectively. 



THE ELBOW-JOINT. 



Dissection. To make the necessary 

 dissection of the ligaments of the 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 digitorum, 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 also be 

 prepared by the removal of the muscles 

 on both surfaces. 



THE ELBOW- JOINT (fig. 39). 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 the outer 

 part of the joint. Where the bones 

 touch, the surfaces are covered with 

 cartilage ; and they are united by the 

 following ligaments : 



The external lateral ligament is a roundish fasciculus, which is 

 attached by one end to a depression below the outer condyle of 

 the humerus, and by the other to the orbicular ligament round the 

 head of the radius. A few of the posterior fibres pass backwards 

 to the. external margin of the olecranon. 



The internal lateral ligament is triangular in shape. It is pointed 

 at its upper extremity, and is connected to the inner condyle of 



Dissection 

 of the elbow- 

 joint. 



FIG. 39. THE LIGAMENTS OF 

 THE ELBOW-JOINT, AND OF 

 THE RADIUS AND ULNA 

 (BOURGERY). 



1. Capsule of the elbow-joint. 



2. Oblique ligament. 



3. Interosseous membrane. 



4. Aperture for blood-vessels. 



5. Tendon of the biceps. 



Bones 

 forming the 

 elbow-joint. 



External 



lateral 



ligament. 



Internal 



lateral 



ligament. 



