THE SMALL METACARPAL BONES ^j 



TLIE SMALL METACARPAL BONES 



These are long bones, the development of which has been aborted. 

 Each consists of a body and a head. The body is a long tapering rod of 

 bone, which presents three surfaces. It is curved in its length. 



The anterior surface is flattened, and for the greater part is roughened 

 for the attachment of the interosseous ligament which unites this bone 

 to the large metacarpal. For about an inch and a half above the lower 

 extremity this surface is smooth and free, and the small and large meta- 

 carpals are here separated from one another by a slight interval. 



The inner surface is the least extensive. It bounds outwardly the 

 channel which accommodates the suspensory ligament. This surface is 

 widest at its upper extremity, and becomes gradually narrower as we 

 descend to the inferior extremity of the bone. 



The outer surface is slightly curved in its length, with the concavity 

 of the curve directed outwards. It is convex in the transverse direction, 

 and is smooth. 



The head of the bone is placed superiorly, and its upper surface is 

 articular, that of the inner bone presenting two facets, whilst on the 

 outer we have only one. The larger of the two facets on the inner bone 

 is for articulation Avith the trapezoid, and the smaller for the magnum. 

 The facet on the outer bone is for articulation with the unciform bone. 



Anteriorly, the head of each small metacarpal bone presents two 

 small, somewhat flattened facets, for articulation with like facets at the 

 back of the upper extremity of the large metacarpal, with which 

 they form synovial joints. Outwardly each head is roughened for the 

 attachment of muscles and Kgaments. 



Each of the small metacarpal bones terminates inferiorly in a small 

 rounded nodular enlargement, which may be readily located in the living 

 animal. This enlargement is frequently termed the " button " of the 

 splint bone, and its position is the more easily detected on account of 



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