Comprehensive Osteopathic Medical Licensing Examination (COMLEX USA) Practice

The anterior and inner thigh is primarily supplied by which dermatome?

1. Dermatome L1-L2

2. Dermatome T10

3. Dermatome L3

4. Dermatome S3-S5

The correct answer is: Dermatome L1-L2

The anterior and inner thigh is primarily supplied by the L2 and L3 dermatomes. These dermatomes correspond to the lumbar spine segments and are responsible for the sensory innervation of the skin over the anterior aspect of the thigh. Specifically, L2 supplies the upper portion and L3 covers the lower portion of the anterior thigh and the medial side of the thigh. While other dermatomes listed may have some sensory input in adjacent regions, they do not significantly contribute to the innervation of the anterior and inner thigh. For instance, T10 is associated with abdominal innervation, which does not pertain to the thigh. Dermatome S3-S5 relates to the perineal area and the lower part of the buttocks, while L1-L2 is more related to the groin and upper medial thigh region rather than primarily the anterior and inner thigh. Therefore, the correct choice takes into consideration the regions that these specific dermatomes cover, highlighting L2 and L3 as the primary contributors to the sensory supply of the anterior and inner thigh.