124 PRACTICAL ANATOMY. 



extends some distance on the anterior surface of the 

 head, terminating in the inner and outer tubercles for 

 the attachment of the lateral ligaments. 



The third metacarpal articulates with the os magnum 

 and second and third metacarpals ; the distal extremity 

 articulates with the first phalanx of the middle finger. 



The fourth metacarpal articulates at the carpus with 

 the unciform, slightly with the os magnum, and also with 

 the third and fifth metacarpals ; its distal end articulates 

 with the first phalanx of the ring-finger. 



The fifth metacarpal bone is the smallest and articu- 

 lates above with the unciform and fourth metacarpal, 

 below with the first phalanx of the little finger. 



All these metacarpal bones are prismoid, having a 

 posterior or dorsal surface and two anterior lateral sur- 

 faces. Each bone is bowed, concave on the anterior sur- 

 face from end to end, and convex posteriorly. Their 

 distal extremities, or heads, are rounded, and form the 

 knuckles in flexion of the phalanges. Together with 

 the bones of the carpus they make the osseous palm, 

 which is convex posteriorly and concave anteriorly. 



THE PHALANGES. 



The phalanges are fourteen in number, two for the 

 thumb and three for each of the fingers. They are long 

 bones, each developed by two centres. Each bone pre- 

 sents a base, shaft, and head, or distal extremity. 



The phalanges of the first row are strong, cylindri- 

 cal, flattened, and each presents a broad base for articu- 

 lation with the head of a metacarpal. The shaft is flat- 

 tened. The heads present two feebly-marked condyles 

 for articulation with the bones of the second row. 



The phalanges of second row are similar to those of 

 the first, but smaller ; the thumb has no second phalanx. 



