MSK - Obturator Nerve

Question 1

What are the nerve roots of the obturator nerve?

Answer 1

L2-L4

Question 2

What are the motor functions of the obturator nerve?

Answer 2

Innervates the medial (adductor) compartment of the thigh

Question 3

What are the sensory functions of the obturator nerve?

Answer 3

Cutaneous branch innervates the skin of the medial thigh

Question 4

In the first part of its anatomical course, where does the obturator nerve descend through?

Answer 4

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

Question 5

After descending through the first part of its anatomical course, where does the obturator nerve run?

Answer 5

Runs posteriorly to the common iliac arteries and laterally along the pelvic wall to the obturator foramen

Question 6

In the final art of its anatomical course, where does the obturator nerve enter the thigh? What does it then do?

Answer 6

Enters through the obturator canal

Splits into anterior and posterior divisions

Question 7

Between what muscles does the anterior division of the obturator nerve descend through?

To what muscles does it give branches off to?

What does it then branch off to and become?

Answer 7

Adductor Longus and adductor brevis

Gives branches off to the adductor longus, aductor brevis and gracilis muscles

Pierces the fascia lata to become the cutaneous branch of the obturator nerve

Question 8

What muscle does the posterior division of the obturator nerve descend through?

What muscle does is pass and give branches off to?

Answer 8

Obturator Externus

Passes anteriorly to adductor magnus and then gives branches off to supply it

Question 9

What muscles does the obturator nerve innervate in the medial compartment of the thigh?

Answer 9

All of them except the hamstring part of the adductor magnus

Adductor Longus

Adductor Brevis

Adductor Magnus

Gracilis

Obturator Externus

Question 10

Where does the cutaneous branch of the obturator nerve supply?

Answer 10

Middle part of the medial thigh

Question 11

What surgeries can damage the obturator nerve?

Answer 11

Surgeries involving the pelvis or abdomen

Question 12

How would damage to the obturator nerve clinically present?

Answer 12

Numbness

Paraesthesia on the medial aspect of the thigh and weakness in adduction of the thigh

Alternatively, the patient could present with posture and gait problems due to the loss of adduction

Question 13

When is Obturator Nerve block used?

Answer 13

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

Question 14

Where is the anaethetic injected in obturator nerve block?

How could the procedure be guided?

Answer 14

Inferior to the pubic tubercle and lateral to the tendon of the adductor longus muscle

Using an ultrasound