A dermatome is the area of skin supplied with sensory innervation by which of the following?

• A. A single artery
• B. Multiple cranial nerves
• C. A single spinal nerve
• D. The autonomic nervous system

Answer: (C)

Verified step by step guidance

1. Understand the term 'dermatome': A dermatome is a specific area of skin that is innervated by sensory fibers from a single spinal nerve. This concept is crucial in understanding the organization of the peripheral nervous system.
2. Recognize the role of spinal nerves: Each spinal nerve corresponds to a specific segment of the spinal cord and provides sensory input to a defined area of skin. This is why dermatomes are mapped to specific spinal nerves.
3. Differentiate between spinal nerves and cranial nerves: Spinal nerves are responsible for dermatomal innervation, while cranial nerves primarily innervate the head and neck regions. Multiple cranial nerves do not supply a single dermatome.
4. Clarify the role of the autonomic nervous system: The autonomic nervous system regulates involuntary functions like heart rate and digestion, but it does not directly contribute to sensory innervation of the skin. Therefore, it is not involved in dermatomes.
5. Conclude that the correct answer is 'A single spinal nerve': Dermatomes are defined by the sensory innervation provided by individual spinal nerves, making this the correct choice.