Dermatome innervation closely aligns with myotome innervation. Which best characterizes this statement?

• A. True
• B. False
• C. Not related
• D. Only in the thoracic region

Answer: (A)

The connection between dermatomes and myotomes comes from the same spinal segmental organization. Each spinal nerve root carries sensory fibers that supply a skin area (a dermatome) and motor fibers that control a muscle group (a myotome). Because they originate from the same segment, the areas of skin affected and the muscles affected tend to line up, so people often show a matched pattern of sensory loss and muscle weakness when a nerve root is involved. Therefore, the statement is true. Keep in mind there is some overlap between adjacent dermatomes and some muscles receive input from multiple roots, so the correspondence isn’t perfectly one-to-one in every person.