We have looked at the movements of the thumb and the motor innervation to some of those muscles. Let's now look at the sensory innervation from the skin of the hand.
A knowledge of how the main nerves of the forearm and hand (ulnar, median and radial) are distributed to the skin of the hand allows us to test their function. Assessing sensation would involve testing the four modalities of pain, touch, temperature and vibration. As with motor distribution, remember that the boundaries between dermatomes vary slightly between individuals.
Cutaneous sensory innervation video.