SCAPHOID BONE. SEMILUNARE. 



83 



by its convex surface with the 

 Fig. 37.* 



is, however, more similar in form to a cashew nut, flattened and con- 

 cave upon one side. If carefully examined, it will be found to pre- 

 sent a convex and a concave surface, a convex and a concave border, 

 a broad end, and a narrow and pointed extremity, the tuberosity. 



To ascertain to which hand the bone belongs, let the student hold 

 it horizontally, so that the convex surface may look backwards 

 (t. e. towards himself), and the convex border upwards : the broad 

 extremity will indicate its appropriate hand ; if it be directed to the 

 right, the bone belongs to the right ; and if to the left, to the left 

 carpus. 



Articulations. With five bones ; 

 radius ; by its concave surface, with 

 the os magnum and semilunare ; 

 and by the extremity of its upper 

 or dorsal border, with the trape- 

 zium and trapezoides. 



Attachments. By its tuberosity 

 to the abductor pollicis, and ante- 

 rior annular ligament. 



The SEMILUNAR bone may be 

 known by having a crescentic con- 

 cavity, and a somewhat crescentric 

 outline. It presents for examina- 

 tion four articular surfaces and two 

 extremities ; the articular surfaces 

 are, one concave, one convex, and 

 two lateral, one lateral surface being 

 crescentic, the other nearly circu- 

 lar, and divided generally into two 

 facets. The extremities are, one 

 dorsal, which is quadilateral, flat, 

 and indented, for the attachment 



of ligaments ; the other palmar, which is convex, rounded, and of 

 larger size. 



To determine to which hand it belongs, let the bone be held per- 

 pendicularly, so that the dorsal or flat extremity look upwards, and 

 the convex side backwards (towards the holder). The circular lateral 



* A diagram shewing the dorsal surface of the bones of the carpus, with 

 their articulations. The right hand. R. The lower end of the radius. 

 U. The lower extremity of the ulna. F. The inter- articular fibro- cartilage 

 attached to the styloid process of the ulna, and to the margin of the articular 

 surface of the radius. S. The scaphoid bone: the numeral (5) indicates the 

 number of bones with which it articulates. L. The semilunare articulating 

 with five bones. C. The cuneiforme, articulating with three bones. P. The 

 pisiforme, articulating with the cuneiforme only. T. The first bone of the 

 second row, the trapezium, articulating with four bones. T. The second 

 bone, the trapezoides, articulating also with four bones. M. The os magnum, 

 articulating with seven. U. The unciforme, articulating with five. The nu- 

 merals, 1,3, 1,2, 1, on the metacarpal bones, refer to the number of their arti- 

 culations with the carpal bones. 



