186 
MR. VOUATT’s VETERINARY LECTURES. 
muscles in their respective neighbourhoods, but a small branch 
of the sixth, and the greater portion of the three others, go to 
form a singularly complicated plexus of nerves, whence proceed 
branches to the external thoracic muscles, the scapula, and the 
whole of the fore extremity. The external thoracic nerve in the 
horse supplies the muscles of the breast and side, and even goes 
to the serratus and the latissimus dorsi, and the panniculus car- 
nosus. The scapular ramifies on the muscles on the outer and 
inner side of the scapula, giving branches to the triceps, the 
teres minor, and the levator humeri. The external cutaneous 
nerve of the human being is not found, but the spiral , or rather 
a branch from it, and not from the ulnar as asserted by Cuvier, 
supplies the place of it; while the spiral , and the radial , bestow 
nervous influence on the upper part of the extremity, and the 
ulnar on the whole of it, and with no other difference than oc¬ 
curs from the one phalanx of the horse, the two which constitute 
the foot of the ox, and the four that are found in that of the dog. 
The Principle of Neurotomy .—In the metacarpal and the 
plantar nerves of the horse, the ox, and the sheep, we have an 
interesting illustration of the distribution of the filaments of dif¬ 
ferent function, of which the compound spinal nerve is composed. 
There are no muscles below the knee in these animals, and as it 
seems to be a law of nature that nothing is given which is not 
required, we imagine that the motor fibrils cease to exist below 
the knee, for there they would be useless; and accordingly, in 
the operation of neurotomy, we destroy the sensibility of the 
foot, and relieve a noble animal from that torture which in va¬ 
rious diseases of the foot our own ill management or barbarous 
usage had inflicted upon him ; but we take away no muscular 
power, and no otherwise interfere with the action of the limb, 
than by giving some incertitude of motion and increase of con¬ 
cussion, which must plainly be the consequence of the loss of 
sensibility in the part. 
The Nerves of the Wing in Birds .—These spring from the last 
cervical and the two first dorsal nerves. The plexus is more 
regular and compact than in the quadruped. The pectorals, as 
may be imagined when we observe the muscles of the breast in 
the bird, are of great comparative bulk, and there are four of 
them. Two nervous chords only are sent to the wing; the first, 
taking its course under the inferior surface of the wing, answers 
to the spiral and the ulnar nerves; the other, turning round the 
humerus to reach the superior surface, is the radial nerve. 
The Dorsal Nerves. —We have observed the spinal chord en¬ 
larging at the inferior part of the neck, that the nerves which 
are to form the humeral plexus may be sufficiently developed. 
