Obturator Nerve

Original Editor - Jin Yoo

Top Contributors - Jin Yoo, Lucinda hampton, Leana Louw, Mariam Hashem and Kim Jackson

Description

obturator nerve

The obturator nerve arises from the lumbar plexus on the posterior abdominal wall and descends within the psoas muscle, emerging from the medial margin of the muscle to enter the pelvis. The nerve path continues by following along the lateral wall of the pelvis, passing through the obturator canal, to enter the medial compartment of the thigh. From here the nerve divides into the anterior and posterior branch which are separated by the adductor brevis muscle.

• The posterior branch travels underneath the adductor muscle along the anterior surface of the adductor magnus muscle, innervating the obturator externus, adductor brevis, as well as part of the adductor magnus muscle that is attached to the linea aspera.
• On the anterior surface of the adductor brevis muscle the anterior branch travels underneath the pectineus and adductor longus muscles to innervate the adductor longus, gracilis, and adductor brevis muscles. This branch also often contribute to the pectineus muscle. The cutaneous branches innervate the skin on the medial thigh.

Root

L2 - L4

Branches

Posterior Branch

Anterior Branch

Cutaneous Branch

Function

Motor

• Obturator Externus
• Adductor Longus
• Adductor Brevis
• 1/2 Adductor Magnus (the adductor portion)
• Gracilis
• Pectineus (occasional twig)

Sensory

• Hip joint
• Knee joint
• Medial skin over adductors (contributes together with saphenous and medial femoral cutaneous nerve)

Clinical Relevance

Injury to the nerve is rare as it lies deep within the pelvis and medial thigh. It can be damaged through direct injury to the nerve or to surrounding muscle tissue. Mild damage to the obturator nerve can be treated with physical therapy. More severe cases may require surgery.

Injury may be caused by:

• Nerve being stretched during surgery
• Entrapment within the obturator canal
• Compression during pregnancy
• Car or household accident
• Abdominal surgery
• Athletes may present with pain that may be brought on by exercise, often sports involving a lot or running and twisting. They may have been predisposed to this injury by previous pelvic trauma or surgery.

In mild damage physiotherapy treatment is employed. More severe cases may require surgery with follow up rehab physiotherapy. Axonal growth is at about 1mm per day.

Symptoms of Obturator Neuropathy:

• sensory alteration in medial thigh
• pain & paresthesias may extend from hip to knee along the medial aspect of the thigh
• extension or lateral leg movement can increase pain
• may have trouble walking or experience leg weakness due to problems adducting the ipsilateral hip

Signs of Obturator Neuropathy:

• weak hip adductors on affected side
• wasting of medial thigh
• abnormal abduction of hip during ambulation resulting in a circumducting, wide-based gait
• area of sensory loss or alteration in the mid and lower third of the medial thigh which sometimes may extend below the knee
• ipsilateral loss of the hip adductor tendon reflex (test against asymptomatic leg as is not always present in healthy population)

Assessment

1. Needle EMG to confirm acute/chronic denervation of hip adductors excluding other lower extremity muscles such as iliopsoas or quadriceps
2. CT, MRI, or ultrasound imaging when intra-pelvic mass lesions are suspected of entrapping the nerve

Treatment

Tipton JS, 2008	pharmacologic management of pain: NSAIDs physiotherapy to improve strength and preserve mobility as well as ambulation surgery considered if conservative treatments are non-effective
Sorenson EJ. Chen JJ. Daube JR. 2002	patients with acute onset of obturator neuropathy had good recovery with conservative management patients with chronic neuropathy have poorer outcome
Bradshaw C. McCrory P. Bell S. Brukner P. 1997	good outcomes from surgical release physiotherapy should be part of the rehabilitation plan expected time for return to activity is 3 - 6 weeks