Obturator nerve

Question 1

Anatomical course of obturator nerve

Answer 1

Descends through psoas major and emerges from its medial border, running posterior to common iliac arteries and laterally along pelvic wall to obturator foramen.
It then enters the thigh through the obturator canal and divides into anterior and posterior divisions.

Question 2

Anatomical course of anterior division

Answer 2

Descends between adductor longus and brevis muscles, giving off branches to the adductor longus, adductor brevis and gracilis muscles.
It then pierces the fascia lata to become the cutaneous branch of the obturator nerve.

Question 3

Anatomical course of posterior division

Answer 3

Descends through obturator externus before passing anterior to adductor Magnus and giving off branches to supply it.

Question 4

Motor Innervation

Answer 4

All of medial thigh (except hamstring portion of adductor Magnus)

Adductor longus, brevis and Magnus
Gracilis
Obturator externus

Question 5

Sensory Innervation

Answer 5

Cutaneous branch of obturator nerve gives sensory Innervation to skin over middle part of medial thigh

Question 6

How can it be damaged

Answer 6

During surgery of pelvis or abdomen

Question 7

Symptoms of damage

Answer 7

Numbness
Paresthesia on medial aspect of thigh
Weakness in adduction of thigh
Gait problems

Question 8

When is obturator nerve block used

Answer 8

Management of pain after lower limb surgery or for chronic hip pain

Question 9

Where is the anaesthetic injected in obturator nerve block

Answer 9

Inferior to pubic tubercle

Lateral to tendon of adductor longus

Question 10

Nerve roots

Answer 10

Anterior divisions of L2-4