ARTICULATION OF THE WRIST. 



251 



of the cuneiforme bone. This head is covered by one cartilage, 

 which is so uniform that the different bones cannot be distin- 

 guished from each other. The lower end of the radius i^ arti- 

 culated with this head, but does not cover the whole of it ; a 

 portion of this head, therefore, is under the ulna, but not in 

 contact with that bone : for the cartilage which lines the con- 

 cavity of the radius, is continued beyond the radius, so as to 

 cover the remainder of the head, formed by the carpal bones. 



Fig. 58.* This cartilage which is extended 



from that covering the radius, is 

 attached to a depression on the 

 inner surface of the styloid pro- 

 cess of the ulna. It is called the 

 inter-articular or from its shape the 

 triangular fibro-cartilage. The sy- 

 novial membrane forming the joint 

 between this cartilage and the end 

 of the ulna is loose and is called the 

 sacciform membrane, (see fig. 58.) 

 The lower end of the ulna is in 

 contact with the upper surface of 

 this cartilage, and is articulated lat- 

 erally with the semilunar cavity of 

 the radius. This semilunar cavity 



* A careful dissection being made, the ligaments of the carpus will appear 

 as seen in this and the following figures. 



Dorsal surface, a. External lateral ligament. It runs from the styloid process 

 of radius to os scaphoides. b. Internal lateral ligament which runs from the 

 styloid process of the ulna and divides into two fasciculi, one of which is attached 

 to the pisiform, the other to the cuneiforme bone. d. Posterior or dorsal ligament 

 of the radio-carpal articulation. They are thin and weak and run from the 

 radius to the first row of bones, g. Posterior radio ulnar ligament. . A pos- 

 terior or dorsal thin band of fibres, which connects the two rows of bones 

 together. L "Dorsal ligaments, which connect the metacarpal bones together at 

 their base. n. Dorsal ligament connecting the anterior ends of these bones. 

 o. A middle dorsal ligament stretched from the second metacarpal bone to the 

 trapezoid. p. An external ligament running from this bone to the trapezium; 

 another internal one running from this bone to the os magnum, is not here seen. 

 r. An oblique ligament, running from the os unciforme to the third metacarpal 

 bone. s. Capsular ligament of the metacarpo-carpal articulation of the thumb. 

 t. A sort of capsular ligament of the metacarpo-carpal joint of the little finger. 

 n. The place of dorsal ligament supplied in a great measure by extensor tendon. 

 z. Lateral ligament. 



