Comprehensive Osteopathic Medical Licensing Examination (COMLEX USA) Practice

What does Dermatome C7 refer to?

1. Ring/little finger

2. Thumb

3. Medial upper arm

4. Nipple

The correct answer is: Ring/little finger

Dermatome C7 is specifically associated with the sensory distribution of the seventh cervical spinal nerve. It primarily covers the area of the hand and fingers, particularly affecting the index and middle fingers, as well as parts of the ring finger. The correct choice refers to the ring and little fingers, which fall under the sensory innervation provided by the C7 nerve root. When mapping out dermatomes, it's important to understand that C7 does not directly innervate the thumb, the medial upper arm, or the region of the nipple, as those areas are served by different cervical nerves (C6 for the thumb, C8 for the little finger, T2 for the medial upper arm, and T4 for the nipple). Understanding the distribution of dermatomes is crucial for diagnosing and treating conditions related to nerve root injuries or diseases, as it helps identify the location of sensory deficits based on the affected spinal nerve.