THE HAND. 193 



extensor muscles of the thumb and the indicator lying upon it. 

 The external surface presents a roughness, just above its mid- 

 dle, for the insertion of the pronator teres ; and below it is co- 

 vered by the radial extensors, which are crossed by the exten- 

 sor metacarpi pollicis and the extensor minor. 



The body of the radius is compact ; its extremities are cel- 

 lular. 



SECT. IV. OF THE HAND. 



The. hand consists of carpus, metacarpus, and phalanges, and 

 has in its composition twenty-seven bones, to which number 

 may be added the two sesamoids. 



Of the Carpus, (Carpe.) 



The carpus, or wrist, is next to the bones of the fore arm. 

 Eight bones compose it, which are arranged into two rows, one 

 adjoining the fore arm, and the other the metacarpus : they 

 are called first and second rows. These bones present very 

 diversified forms, and a number of articular faces, which ren- 

 der them difficult to be distinguished from each other. 



The first or antibrachial row has in it the os scaphoides, lu- 

 nare, cuneiforme, pisiforme. The second or metacarpal row 

 has in it the os trapezium, trapezoides, magnum, and unci- 

 forme. 



Of the Scaphoides, (Scaphoide,) 



This bone is on the styloid half of the end of the radius, and 

 is distinguishable in a set by its greater length. It is convex 

 above and concave below. The convexity forms only a half 

 of its upper surface, the other half being rough, and making a 

 knob at its extremity. The concavity on the lower surface is 

 large enough to receive the end of a finger. Between the 

 concavity and the convexity, and on the dorsal surface of the 

 bone, at its outer end, is a second convexity, of an oblong shape. 

 Between the two convexities is a small fossa for the capsular 

 ligament. The palmar, or anterior face, shows a crook in the 



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