Nerves - Obturator

Question 1

What nerve roots make up the obturator nerve?

Answer 1

L2, L3, L4

Question 2

Motor function?

Answer 2

Innervates the muscles of the medial compartment of thigh (e.g. obturator externus, adductor longus, adductor brevis, adductor magnus and gracilis).

Question 3

Sensory functions?

Answer 3

Cutaneous branches of the obturator nerve innervates the skin of the thigh.

Question 4

Anatomical course?

Answer 4

Descends through the fibres of the psoas major and emerges from its medial border.

It then passes posteriorly to the common iliac artery and along the pelvic inlet, before exiting through the obutrator foramen into the medial thigh. It then gives off an anterior and posterior branches.

Question 5

Clinical relevance: damage to the obturator nerve

Answer 5

Can be damaged during surgery involving the pelvis and abdomen.

Symptoms include numbness and paraesthesia to the medial aspect of the thigh and weakness in adduction of the thigh. There could be problems in gait and posture.

Question 6

Clinical relevance: obturator nerve block

Answer 6

Used in management of pain after lower limb surgery and or for chronic hip pain.

Anaesthetic is injected inferior to the pubic tubercle and lateral to the tendon of the adductor longus muscle. This can be done with ultrasound scan guidance.