Obturator nerve lesion causes weakness in which movement?

Obturator nerve lesion causes weakness in which movement?

• A. Thigh adduction
• B. Knee extension
• C. Ankle plantarflexion
• D. Thigh abduction

Answer: (A)

The muscle actions supplied by the obturator nerve are in the medial (adductor) compartment of the thigh, so a lesion here weakens thigh adduction. The obturator nerve carries motor fibers to the adductor longus, adductor brevis, part of adductor magnus, gracilis, and obturator externus, enabling bringing the thigh toward the midline. Since other movements use different nerves—knee extension relies on the femoral nerve, ankle plantarflexion on the tibial portion of the sciatic nerve, and thigh abduction on the gluteal nerves—the weakness is specific to adduction.

The muscle actions supplied by the obturator nerve are in the medial (adductor) compartment of the thigh, so a lesion here weakens thigh adduction. The obturator nerve carries motor fibers to the adductor longus, adductor brevis, part of adductor magnus, gracilis, and obturator externus, enabling bringing the thigh toward the midline. Since other movements use different nerves—knee extension relies on the femoral nerve, ankle plantarflexion on the tibial portion of the sciatic nerve, and thigh abduction on the gluteal nerves—the weakness is specific to adduction.