Which nerve is associated with the lateral thigh sensory distribution and can be affected by entrapment?

Which nerve is associated with the lateral thigh sensory distribution and can be affected by entrapment?

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

Answer: (B)

The nerve that supplies sensation to the outer (lateral) thigh and is commonly compressed as it passes under the inguinal ligament near the anterior superior iliac spine fits this scenario. The lateral femoral cutaneous nerve is a purely sensory branch of the lumbar plexus (L2–L3) that travels from the pelvis toward the thigh and emerges near the ASIS before crossing under the inguinal ligament. When it becomes entrapped, it causes meralgia paresthetica—numbness, tingling, or burning on the lateral thigh, typically without motor weakness. Other nerves listed have different areas of skin coverage or motor roles: the femoral nerve mainly innervates the anterior thigh with quadriceps motor function (and the saphenous nerve provides medial-leg sensation); the obturator nerve covers the medial thigh; the ilioinguinal nerve supplies a small region of the upper medial thigh and parts of the external genitalia. Thus, the lateral femoral cutaneous nerve best matches the lateral thigh sensory distribution and its entrapment.

The nerve that supplies sensation to the outer (lateral) thigh and is commonly compressed as it passes under the inguinal ligament near the anterior superior iliac spine fits this scenario. The lateral femoral cutaneous nerve is a purely sensory branch of the lumbar plexus (L2–L3) that travels from the pelvis toward the thigh and emerges near the ASIS before crossing under the inguinal ligament. When it becomes entrapped, it causes meralgia paresthetica—numbness, tingling, or burning on the lateral thigh, typically without motor weakness. Other nerves listed have different areas of skin coverage or motor roles: the femoral nerve mainly innervates the anterior thigh with quadriceps motor function (and the saphenous nerve provides medial-leg sensation); the obturator nerve covers the medial thigh; the ilioinguinal nerve supplies a small region of the upper medial thigh and parts of the external genitalia. Thus, the lateral femoral cutaneous nerve best matches the lateral thigh sensory distribution and its entrapment.