Muscles that are short and tight can squeeze nerves. Nerves within a muscle can be compressed to the point that they send distorted signals: numbness, sensitivity, swelling,and burning sensations can be the result.
An occasional cause of severe lameness is radial nerve paralysis. The radial nerve is damaged by being overstretched. This condition is common in draft horses, due to their front end conformation. Carriage horses working on web streets also are in danger of this injury. Young horses, racing and playing in wet fields will sometimes do sliding stops when running full tilt into a fence or other obstacle. It is this kind of movement that can overextend the leg and damage the radial nerve.
Keeping your horse fit and balanced is the best insurance for avoiding injuries and problems of the nervous and muscular system. Structural integration has been shown, in both humans and animals, to improve functions of the nervous system.