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dr.dodson

nerves of the forelimb
proximal nerves similar to dog...suprascapular, axillary(teres 
major,minor and deltoids), subscapular etc..

musculocutaneous nerve goes to biceps and coracobrachialis. note 
coracobrachialis much bigger in horse than in dog. musculocutaneous runs 
through coracobrachialis into biceps. then, also travels with median 
nerve and then splits off and branches to the brachialis muscle. the 
brachialis muscle works with the biceps, both insert on radius and flex 
elbow, but in horse can be hard to find. it's sandwiched between biceps 
and extensor carpi radialis. it's a big strong muscle but covered by 
fascia. so distal branch of musculocutaneous goes to brachialis. then 
medial cutaneous antebrachial nerve is the sensory branch of the 
musculocutaneous nerve, and it runs across the lacertus fibrosus, which 
is the tendinous band which is part of the passive stay apparatus which 
is between the biceps brachii and the fascia of the extensor carpi 
radialis. this branch of musculocutaneous goes as far distally as the 
metacarpophalangeal joint.

in horses the radial nerve which is on the lateral side stops at the 
level of the carpus. it does not go down the limb like the 
musculocutaneous. this is a very unusual pattern compared to humans, 
carnivores, ruminants. in the horse this nerve stops short, and there is 
a compensation for that, because you need innervation on the dorsal 
surface, and this comes from the ulnar nerve, which comes down on the 
caudal surface, and crosses to the dorsal surface at the level of the 
carpus, with a palmar branch continuing to the distal phalanx.

median nerve runs down palmar surface of limb. at level just distal to 
carpus is medial palmar nerve, at level distal to fetlock is medial 
digital nerve. at level of carpus, splits off a lateral palmar nerve, 
which continues as lateral digital nerve distal to fetlock. the ulnar 
nerve comes down and joins the lateral palmar nerve at the level of the 
carpus, such that it is fused with the lateral palmar and lateral digital 
nerves. there is a communicating branch of th median nerve between the 
medial and lateral branches mid-proximal phalanx (proximal to the 
proximal sesamoids).

the ulnar nerve also has a dorsal branch, which splits off at the level 
of the carpus.

at level of fetlock, there are dorsal branches of the medial and lateral 
digital nerves. (recall that the medial digital nerve is a continuation 
of the median nerve, and the lateral digital nerve is a compound nerve 
made of a lateral branch of the median nerve and a distal-palmar 
continuation of the radial nerve.

recall the splint bones on the palmar surface of the metacarpal bone. 
there are metacarpal nerves which are very deep, and which come right off 
the back of the carpus which he's simply pointing out, that the ends 
emerge from under the splint bones and go to the joint capsule of the 
fetlock. these metacarpal nerves aren't really something you'll see. 
they're totally covered at their origin. if you do equine surgery you'll 
learn all about them.

also note that the musculocutaneous /dorsal branches are very superficial 
and may be lost in dissection. but, still be aware of them.
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