28 DISEASES OF THE HORSE’S FOOT 
where they form an arch between the deep flexor and the 
suspensory ligament. From this arch (named the Sesa- 
moidean) proceed the Metacarpal Veins. 
Tur MeracarpaL Verns.—Three in number, they are 
distinguished as an Internal and an External Metacarpal, 
and a Deep or Interosscous Metacarpal. As we shall be 
concerned with these in the higher operation of neurectomy, 
we may give them brief mention. : 
Tue Internat Meracarpat Vern, the largest of the three, 
has relations with the internal metacarpal artery and the 
internal plantar nerve. ‘These relations were shortly dis- 
cussed under the section devoted to the arteries, to which 
the reader may refer. 
Tue Exrernay Meracarpan Vern.—This ascends on the 
external side of the flexor tendons in company with the 
external plantar nerve. 
The Interosseous Vein.—This is an irregular vessel 
running up between the suspensory ligament and the 
posterior face of the large metacarpal bone. 
F. THE NERVES. 
Tue Puantar Nerves.—These are two in number, and 
are distinguished as Internal and External. 
Tue Internat Puantar Nerve lies behind and in close 
contact with the great metacarpal artery during that vessel’s 
course down the region of the cannon. A point of interest 
is that it gives off at about the middle of the cannon a 
branch which bends obliquely downwards and behind the 
flexor tendons to join its fellow of the opposite side— 
namely, the external plantar. This it joins an inch or 
more above the bottom of the splint bone. Measured in a 
straight line, this is about 23 inches below its point of 
origin. Near the fetlock, at the level of the sesamoids, 
the internal plantar nerve ends in several digital branches. 
Tue Exrernan Puanrar Nerve.—This holds a position 
to the outside of the metacarpal region, analogous to that 
of the internal plantar nerve on the inside of the limb, 
running down on the external edge of the flexor tendons. 
