If a single spinal nerve is cut, the area of tactile loss is always greater than the area of loss of painful sensations, because:
C i.e. Degree of overlap of fibres carrying tactile sensation is much less. - Degree of overlap of fibres is much lessQ - Greater Overlap of pain sensory units. - Lack of collateralization from adjacent tactile fibres - Rapid collateral regeneration of pain fibres Sensory changes due to interruption of a single peripheral nerve vary, depending on whether the nerve involved is predominantly muscular, cutaneous or mixed. Following injury to a cutaneous nerve, the area of sensory loss is always less than its anatomic distribution because of overlap from adjacent nerve. But area of sensory loss for touch > painQ.
Tactile information is carried by myelinated fast conducting fibres
Tactile receptors adapt quickly
Degree of overlap of fibres carrying tactile sensation is much less
In the primary sensory coex tactile sensation is represented on a larger area