CARPUS. 191 



Carpus. 



No part of the skeleton is more complex than the carpus. The following descrip- 

 tion will, therefore, be of little use to a young student, unless the bones are 

 before him when he is reading it. Great advantage will be derived from 

 examining two sets of carpal bones: each set belonging to the same side. 

 In one of these sets the bones should be connected by their natural ligaments ; 

 but the two rows separated from each other. The bones of the other set 

 should be accurately cleaned; so that their forms and surfaces may be examined. 



The carpus is composed of eight small bones, arranged in two 

 rows ; one of which rows is attached to the bones of the fore- 

 arm, and the other to the body of the hand. 



These bones are named from their figure and shall be 

 mentioned in the order in which they occur, beginning with the 

 row next to the forearm ; and with the external bone in each 

 row. 



They are, Os Scaphoides, Lunare, Cuneiforme, Pisiforme, 

 forming the upper row ; Os Trapezium, Trapezoides, Magnum, 

 and Unciforme, forming the lower row. 



First Row. 



Os scaphoides is the largest of the eight, excepting one. It 

 is convex above, concave and oblong below ; from which small 

 resemblance to a boat, it has got its natne. Its smooth convex 

 surface is divided by a rough middle fossa, which runs obliquely 

 across it. The upper largest division is articulated with the 

 radius. The common ligament of the joint of the wrist is fixed 

 into the fossa ; and the lower division is joined to the trapezium 

 and trapezoides. The concavity receives more than half of the 

 round head of the os magnum. The internal side of this hollow 

 is formed into a semilunar plane to be articulated with the 

 following bone. The external, posterior, and anterior edges are 

 rough, for fixing the ligaments that connect it to the surrounding 

 bones. 



Os lunare has a smooth convex upper surface, by which it is 

 articulated with the radius. The external side, which gives 

 the name to the bone, is in the form of a crescent, nad is 

 joined with the scaphoid : the lower surface is hollow, for 

 receiving part of the head of the os magnum. On the inside 



