Final answer:
Dermatomes are regions of the skin innervated by specific spinal nerves. They help detect touch and relay information to the brain for perception. Testing sensory fields within dermatomes helps assess spatial specificity of perception.
Step-by-step explanation:
Dermatomes are regions of the skin that are innervated by specific spinal nerves. The surface of the skin can be divided into these topographic regions based on the sensory endings in the skin that connect to the spinal nerves. These sensory endings detect touch and relay information to the brain for perception. For example, the fibers of the eighth cervical nerve innervate the medial surface of the forearm and extend out to the fingers. Testing the sensory fields within dermatomes helps assess spatial specificity of perception.