ARTICULATIONS i, 



the humerus just above the coronoid fossa ; and below to the 

 coronoid process, and the front of orbicular ligament. 



The posterior ligament is attached, above to the upper 

 border of the olecranon fossa ; below, to the margin of the 

 olecranon. 



The internal lateral ligament is triangular in shape ; it is 

 attached, above to the inner condyle of the humerus ; the 

 fibres diverge as they descend, the anterior ones going to the 

 inner margin of the coronoid process, the posterior to the 

 inner margin of the olecranon. 



The external lateral ligament, smaller than the preceding, 

 is attached, above to a depression below the external condyle, 

 and below to the orbicular ligament, some of the fibres being 

 prolonged to the outer edge of the ulna. 



The synovial membrane is very large, covering the articular 

 surfaces of the humerus, ulna, and radius ; it also serves for 

 the upper radio-ulnar articulation. 



VI. THE RADIO-ULNAR ARTICULATIONS. 



(a) Superior Radio-ulnar Articulation (lateral ginglyinus). 

 The orbicular ligament surrounds the head of the radius. 



It is attached to the two ends of the lesser sigmoid cavity, 

 and is wider above than below. The outer surface is con- 

 nected with the external lateral ligament. The internal 

 surface is lined with synovial membrane continuous with 

 that of the elbow-joint. 



(b) Middle Radio-ulnar Articulation. 



The oblique or round ligament is a fibrous cord passing 

 downwards and outwards from the tubercle at the base of the 

 coronoid process, to a little below the tubercle of the radius. 



The interosseous membrane passes downwards and inwards 

 (the opposite to the preceding) from the radius to the ulna ; 

 it is attached to the interosseous border of each bone. 



(c) Inferior Radio-ulnar Articulation (lateral ginglymus). 

 The anterior radio ulnar ligament passes from the anterior 



edge of the radial sigmoid cavity to the anterior surface of 

 the head of ulna. 



The posterior radio-ulnar ligament extends similarly upon 

 the posterior surface. 



The triangular fibro cartilage passes transversely beneath 

 the lower end of the ulna, between its styloid process and the 

 radius. Its apex is attached to the outer side of base of the 

 styloid process of ulna, and the base to the edge of the radius 

 between the sigmoid cavity and the lower articular surface. 



