UNCIFORME METACARPUS. 



Jlttachments. To the flexor brevis poliicis muscle. 



The UNCIFORME is a triangular-shaped bone, remarkable for a long and 

 curved process, which projects from its palmar aspect. It presents five 

 surfaces ; three articular, and two free. One of the articular surfaces is 

 divided by a slight ridge into two facets; the other two converge, and 

 meet at a flattened angle.* One of the free surfaces, the dorsal, is rough 

 and triangular ; the other, palmar, also triangular, but somewhat smaller, 

 gives origin to the unciform process. 



If the bone be held perpendicularly, so that the articular surface with 

 two facets look upwards, and the unciform process backwards (towards 

 the holder), the concavity of the unciform process will point to the hand 

 to which the bone belongs. 



Articulations. Wkhjfette bones ; by the two facets on its base, with the 

 fourth and fifth metacarpal bones ; by the two lateral articulating surfaces, 

 with the os magnum and cuneiforme ; and by the flattened angle of its 

 apex, with the semilunare. 



Attachments. To two muscles, abductor minimi digiti, and flexor 

 brevis minimi digiti ; and by the hook-shaped process to the annular liga- 

 ment. 



Development. The bones of the carpus are each developed by a single 

 centre ; they are cartilaginous at birth. Ossification commences towards 

 the end of the first year in the os magnum and unciforme ; at the end of 

 the third year in the cuneiforme ; during the fifth year in the trapezium 

 and semilunare ; during the eighth, in the scaphoides ; the ninth, in the 

 trapezoides : and the twelfth in the pisiforme. The latter bone is the last 

 in the skeleton to ossify ; it is, in reality, a sesamoid bone of the tendon 

 of the flexor carpi ulnaris. 



The number of articulations which each bone of the carpus presents 

 with surrounding bones, may be expressed in figures, which will materially 

 facilitate their recollection; the number for the first row is 5531, and for 

 the second 4475. 



METACARPUS. The bones of the metacarpus are five in number. They 

 are long bones, divisible into a head, shaft, and base. 



The head is rounded at the extremity, and flattened at ear h side, for the 

 insertion of strong ligaments ; the shaft is prismoid, and marked deeply 

 on each side, for the attachment of the interossei muscles ; and the base 

 is irregularly quadrilateral and rough, for the insertion of tendons and 

 ligaments. The base presents three articular surfaces, one at each side, 

 for the adjoining metacarpal bones ; and one at the extremity for the 

 carpus. 



The metacarpal bone of the thumb is one-third shorter than the rest, 

 flattened and broad on its dorsal aspect, and convex on its palmar side; 

 the articular surface of the head is not so round as that of the other meta- 

 carpal bones ; and the base has a single concavo-convex surface, to arti- 

 culate with the similar surface of the trapezium. 



The metacarpal bones of the different fingers may be distinguished by 

 certain obvious characters. The base of the metacarpal bone of the index 

 finger is the largest of the four, and presents four articular surfaces. That 

 of the middle finger may be distinguished by a rounded projecting process 



When *he unciforme does not articulate with the semilunare, this angle is sharp 



