A dermatome is defined as which of the following?

A dermatome is defined as which of the following?

• A. A region of skin supplied by a single spinal nerve
• B. A region of body wall supplied by a single pair of dorsal root ganglia
• C. A muscle group innervated by a single nerve
• D. A brain region controlling sensation

Answer: (B)

Dermatomes map skin sensation to the spinal nerve level that supplies it. The cell bodies of the sensory neurons for these nerves reside in the dorsal root ganglia, and the sensory fibers from a single spinal nerve (and its ganglion) innervate a defined region of skin. Because that region is tied to a specific spinal segment on each side, describing it as the skin area supplied by a single pair of dorsal root ganglia captures the idea that a dermatome corresponds to the sensory input from one spinal level (on a given side) through the associated dorsal root ganglia. This makes it the best fit among the options.

Dermatomes map skin sensation to the spinal nerve level that supplies it. The cell bodies of the sensory neurons for these nerves reside in the dorsal root ganglia, and the sensory fibers from a single spinal nerve (and its ganglion) innervate a defined region of skin. Because that region is tied to a specific spinal segment on each side, describing it as the skin area supplied by a single pair of dorsal root ganglia captures the idea that a dermatome corresponds to the sensory input from one spinal level (on a given side) through the associated dorsal root ganglia. This makes it the best fit among the options.