66 TOPOGRAPHICAL ANATOMY OF 



of the carpus and through the metacarpal region. At the carpus 

 the relative positions of the nerve and artery do not remain con- 

 stant; but in the metacarpus the nerve lies behind the artery. 

 In the metacarpus, therefore, the common digital vein, the common 

 digital artery, and the medial volar nerve lie together in the order 

 in which they are here enumerated, the vein being the most anterior 

 of the three structures. About the middle of the metacarpus an 

 oblique communicating branch from the medial volar nerve crosses 

 the flexor tendons superficially to join the lateral volar nerve. 



The lateral volar nerve (n. volaris lateralis) crosses the surface 

 of the superficial flexor tendon obliquely in order to gain a more 

 lateral position, and, under cover of the tendon of the flexor carpi 

 ulnaris, is joined by the deep or terminal branch of the ulnar nerve. 

 After this union, the volar nerve passes down the back of the carpus, 

 partly embedded in the transverse ligament, and, on reaching the 

 metacarpus, follows the lateral border of the flexor tendons, where 

 it bears the same relations to the lateral volar metacarpal vein and 

 a small branch of the lateral volar metacarpal artery as does the 

 medial nerve to the common digital vessels. For surgical reasons it 

 is necessary to remember that, while the medial volar nerve is 

 accompanied by a large artery, the lateral nerve is related to a 

 small one; and it is further to be noted that the medial nerve is 

 forsaken by the common digital artery when this vessel sinks 

 towards its termination just proximal to the sesamoid bones. 



A deep branch of the lateral volar nerve arises behind the carpus, 

 and terminates in numerous filaments that supply the three inter- 

 osseous muscles. This nerve is of some moment inasmuch as it is 

 responsible for the sensibility of the middle interosseous muscle 

 (suspensory ligament) ; and apparently, like the volar nerve from 

 which it arises, it contains fibres derived from both the ulnar and 

 median nerves. 



On a level with the metacarpo-phalangeal joint each volar nerve 

 divides into two branches : (1) The volar branch (ramus volaris), the 

 larger of the two, follows the posterior border of the digital artery, 

 and will be found again during the examination of the contents of 

 the hoof. (2) The smaller dorsal branch (ramus dorsalis) crosses the 

 digital artery superficially, and runs along the side of the digit 

 between the artery and its companion vein. This branch distributes 

 filaments to the skin in front of the digit, and to the coronary 

 matrix of the hoof. 



It is worthy of observation that, at the middle of the first phalanx, 

 there are commonly three nerves with an artery and vein in close 



