CARPAL ARTICULATIONS. 143 



transversely and longitudinally from bone to bone, upon the dorsal 

 surface of the carpus. 



The palmar ligaments are fasciculi of the same kind, but stronger 

 than the dorsal, having the like disposition upon the palmar surface. 



The interosseous ligaments are fibre-cartilaginous lamellae situated 

 between the adjoining bones in each range : in the upper range they 

 close the upper part of the spaces between the scaphoid, semilunar, and 

 cuneiform bones ; in the lower range they are stronger than in the upper, 

 and connect the os magnum on the one side to the unciforme, on the 

 other to the trapezoides, and leave intervals through which the synovial 

 membrane is continued to the bases of the metacarpal bones. 



The anterior annular ligament is a firm ligamentous band, which 

 connects the bones of the two sides of the carpus. It is attached by 

 one extremity to the trapezium and scaphoid, and by the other to the 

 unciform process of the unciforme and the base of the pisiform bone, 

 and forms an arch over the anterior surface of the carpus, beneath 

 which the tendons of the long flexors and the median nerve pass into 

 the palm of the hand. 



The articulation of the pisiform lone with the cuneiform, is pro- 

 vided with a distinct synovial membrane, which is protected by fasci- 

 culi of ligamentous fibres, forming a kind of capsule around the joint ; 

 they are inserted into the cuneiforme, unciforme, and base of the 

 metacarpal bone of the little finger. 



Synovial Membranes. There are jive synovial membranes entering 

 into the composition of the articulations of the carpus : 



The first is situated between the lower end of the ulna and the in- 

 terarticular fibro-cartilage ; it is called sacciform, from forming a 

 sacculus between the lateral articulation of the ulna with the radius. 



The second is situated between the lower surface of the radius and 

 interarticular nbro-cartilage above, and the first range of bones of the 

 carpus below. 



The third is the most extensive of the synovial membranes of the 

 wrist ; it is situated between the two rows of carpal bones, and passes 

 between the bones of the second range, to invest the carpal extremities 

 of the four metacarpal bones of the fingers. 



The fourth is the synovial membrane of the articulation of the me- 

 tacarpal bone of the thumb with the trapezium. 



The fifth is situated between the pisiform and cuneiform bone. 



Actions. Very little movement exists between the bones in each 

 range, but more is permitted between the two ranges. The motions 

 in the latter situation are those of flexion and extension. 



9. The Carpo-metacarpal Articulations. The second row of bones 

 of the carpus articulates with the metacarpal bones of the four fingers 

 by dorsal and palmar ligaments; and the metacarpal bone of the 

 thumb with the trapezium by a true capsular ligament. There is also 

 in the carpo-metacarpal articulation a thin interosseous band which 

 passes from the ulnar edge of the os magnum to the line of junction 

 between the third and fourth metacarpal bones. 



