316 THE ARTICULATIONS, OR JOINTS 



The dorsal ligaments (ligamenta intercarpea dorsalia) are placed transversely 

 behind the bones of the first row; they connect the scaphoid and semilunar and 

 the semilunar and cuneiform. 



The palmar or volar ligaments (ligamenta intercarpea volaria) connect the 

 scaphoid and semilunar and the semilunar and cuneiform bones; they are weaker 

 than the dorsal, and placed very deeply below the anterior ligament of the wrist. 



The interosseous ligaments (ligamenta intercarpea interossea) (Fig. 256) are two 

 narrow bundles of fibrous tissue connecting the semilunar bone on one side with 

 the scaphoid, and on the other with the cuneiform. They are on a level with 

 the superior surfaces of these bones, and close the upper part of the spaces 

 between them. Their upper surfaces are smooth, and form with the bones the 

 convex articular surfaces of the wrist-joint. 



The ligaments connecting the pisiform bone are: 



Capsular. Two Palmar Ligaments. 



The capsular ligament is a thin membrane which connects the pisiform bone 

 to the cuneiform. It is lined by a separate synovial membrane. 



The two palmar ligaments are two strong fibrous bands which connect the 

 pisiform to the unciform, the pisouncinate ligament (ligamentum pisohamatum), 

 and to the base of the fifth metacarpal bone, the pisometacarpal ligament (liga- 

 mentum pisometacarpeum). 



2. ARTICULATIONS OF THE SECOND Row OF CARPAL BONES. 



These are also arthrodial joints. The articular surfaces are covered with 

 hyaline cartilage, and connected by the following ligaments: 



Dorsal. Palmar. 



Three Interosseous. 



The dorsal ligaments (ligamenta intercarpea dorsalia) extend transversely from 

 one bone to another on the dorsal surface, connecting the trapezium with the trape- 

 zoid, the trapezoid with the os magnum, and the os magnum with the unciform. 



The palmar ligaments (ligamenta intercarpea volaria) have a similar arrange- 

 ment on the palmar surface. 



The three interosseous ligaments (ligamenta intercarpea interossea) (Fig. 256), 

 much thicker than those of the first row, are placed one between the os magnum 

 and the unciform, a second between the os magnum and the trapezoid, and a 

 third between the trapezium and trapezoid. The first of these is much the 

 strongest, and the third is sometimes wanting. 



3. ARTICULATIONS OF THE Two Rows OF CARPAL BONES WITH EACH OTHER 



(Figs. 253, 254). 



The joint between the scaphoid, semilunar, and cuneiform, and the second 

 row of the carpus, or the midcarpal joint, is made up of three distinct portions; 

 in the centre the head of the os magnum and the superior surface of the unciform 

 articulate with the deep, cup-shaped cavity formed by the scaphoid and semilunar 

 bones, and constitute a sort of ball-and-socket joint. On the outer side the trape- 

 zium and trapezoid articulate with the scaphoid, and on the inner side the unci- 

 form articulates with the cuneiform, forming gliding joints. 



