Which nerve provides cutaneous innervation to the skin over the root of the penis or clitoris and the upper medial thigh?

Which nerve provides cutaneous innervation to the skin over the root of the penis or clitoris and the upper medial thigh?

• A. Genitofemoral nerve
• B. Obturator nerve
• C. Ilioinguinal nerve
• D. Lateral femoral cutaneous nerve

Answer: (C)

This question hinges on the distribution of cutaneous sensation to the external genitalia combined with the proximal medial thigh. The ilioinguinal nerve carries sensory fibers from L1 and provides sensation to the skin at the root of the penis or clitoris and the upper medial thigh. It travels through the inguinal canal and exits at the superficial inguinal ring, giving a branch to the anterior scrotum or mons pubis/labia majora in females, as well as the upper medial thigh region. By comparison, other nerves listed cover different areas: the genitofemoral nerve’s genital branch supplies the scrotum or labia majora (and cremaster), but not the upper medial thigh; the obturator nerve supplies the medial thigh; and the lateral femoral cutaneous nerve supplies the lateral thigh. Hence, the nerve that matches both the root of the penis or clitoris and the upper medial thigh is the ilioinguinal nerve.

This question hinges on the distribution of cutaneous sensation to the external genitalia combined with the proximal medial thigh. The ilioinguinal nerve carries sensory fibers from L1 and provides sensation to the skin at the root of the penis or clitoris and the upper medial thigh. It travels through the inguinal canal and exits at the superficial inguinal ring, giving a branch to the anterior scrotum or mons pubis/labia majora in females, as well as the upper medial thigh region.

By comparison, other nerves listed cover different areas: the genitofemoral nerve’s genital branch supplies the scrotum or labia majora (and cremaster), but not the upper medial thigh; the obturator nerve supplies the medial thigh; and the lateral femoral cutaneous nerve supplies the lateral thigh. Hence, the nerve that matches both the root of the penis or clitoris and the upper medial thigh is the ilioinguinal nerve.