“Horses are motor sensory creatures. Their brains tell us so. The brain area in which sensations are processed is referred to as the somatic sensory cortex. If we consider the somatic sensory cortex as a map, its largest areas would represent the most sensitive body areas because these brain areas are most densely-packed with sensory nerves.
If we use the United States as an example, the mouth and lips represent Alaska. The flank, withers, groin and bulbs of the heels represent California, Texas, Montana, and Wyoming. The horse’s chest, although physically rather large, represents a very small state like Delaware in our analogy.”
– Evidence-Based Horsemanship
By Dr. Stephen Peters & Martin Black