Lower Limb

Obturator Nerve

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Overview


The abduction and adduction of the hip is important during gait. The obturator nerve (anterior divisions of the ventral rami of L2-L4) supplies the adductor/medial compartment of the thigh i.e. adductor magnus, longus and brevis, and gracilis.


Gross Anatomy


The Obdurator (L2-4, anterior divisions) nerve is a branch of the Lumbar plexus (ventral rami of L1-L4). It supplies the medial compartment of the thigh i.e. adductor magnus (adductor head), adductor longus, adductor brevis and gracilis. The nerve will first pass through the substance of the psoas major muscle, and will emerge medial to it on order to enter the pelvic brim (the femoral nerve emerges lateral to the psoas major). It continue to descend in the pelvis, behind the common iliac vessels but lateral to the hypogastric vessels. It them runs along the lateral wall of the pelvis, this time I front of the obturator artery and vein. It then passes through the obturator foramen, and will pass downward through the obturator canal.

 

The nerve has an anterior and a posterior division. The anterior division will supply the adductor longus, brevis and gracilis. The posterior division will supply the adductor magnus (adductor head), as well as adductor brevis. The adductor brevis and obturator externus muscles separate the anterior and posterior divisions of the nerve. The nerve also supplies a branch to the knee joint what pierces the oblique popliteal ligament.


Clinical Anatomy


Obdurator nerve block- This technique is used to induce anaesthesia in the for chronic hip pain or lower limb surgery. The needle is directed lateral to the adductor longus muscle and beneath the pubic tubercle.

Quick Anatomy


Key Facts

Developmental precursor- Alar and basal plate of L2-L4

Muscles innervated- Adductor magnus adductor head, adductor longus, adductor brevis, gracilis, obturator externus.

Sensation- Superior medial aspect of the thigh.

Aide-Memoire

The nerve passes through the obturator foramen and obturator canal.

 

It descends down into the pelvis and runs medial to the psoas major muscle. The femoral nerve runs lateral to the psoas major muscle.


Summary


The obturator nerve (anterior divisions of the ventral rami of L2-L4) supplies the medial compartment of the thigh. It also supplies sensation to skin of the superior medial thigh, and provides articular branches to the hip and knee joints.


References


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