The obturator nerve is a major peripheral nerve of the lower limb. It arises from the lumbar plexus and receives fibres from the anterior divisions of L2, L3, and L4. Physiologically, it is responsible for motor and sensory functions in the medial compartment of the thigh. To understand its role in the body, we must look further into its anatomy, functions, and clinical relevance.
After its formation, the obturator nerve descends through the fibres of the psoas major and emerges from its medial border. It then travels posteriorly to the common iliac arteries and laterally along the pelvic wall - towards the obturator foramen of the pelvis. The obturator nerve enters the medial thigh via the obturator canal (formed within the obturator foramen by the obturator membrane). It then divides into anterior and posterior branches.
The anterior division of the obturator nerve descends in a plane between the adductor longus and adductor brevis (towards the femoral artery). It supplies motor fibres to the adductor longus, adductor brevis, and gracilis muscles. Additionally, it can also supply the pectineus muscle. It then pierces the fascia lata to become the cutaneous branch of the obturator nerve.
The posterior division of the obturator nerve pierces the obturator externus muscle, and then descends in a plane between the adductor brevis and adductor magnus. It innervates the obturator externus and adductor magnus muscles.
The obturator nerve innervates all the muscles in the medial compartment of the thigh – except the hamstring part of the adductor magnus (innervated by the tibial nerve). They are collectively known as the hip adductors, and are as follows:
The cutaneous branch of the obturator nerve supplies the skin of the middle part of the medial thigh.
The obturator nerve can be damaged during surgery involving the pelvis or abdomen. Symptoms include numbness and 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.
Obturator nerve block is used in the management of pain after lower limb surgery or for chronic hip pain. The anaesthetic is injected inferior to the pubic tubercle and lateral to the tendon of the adductor longus muscle. This procedure can also be carried out under ultrasound guidance.
The obturator nerve is a nerve originating from the lumbar plexus. It is composed of both motor and sensory fibers, and it supplies the medial compartment of the thigh. The obturator nerve has motor functions, including innervation of the adductor longus, adductor brevis, adductor magnus, adductor part, hamstring part, and gracilis muscles that are collectively known as the hip adductors. It also supplies sensation to the medial and anteromedial parts of the thigh, and the cutaneous branch of the obturator nerve provides sensation to the skin of the middle part of the medial thigh.
Damage to the obturator nerve can be caused by trauma, such as a gunshot wound. Symptoms include numbness and paraesthesia on the medial aspect of the thigh, as well as weakness in adduction of the thigh. This may lead to posture and gait problems due to the loss of adduction.
The obturator nerve can also be damaged during surgery involving the pelvis or abdomen. Surgeons must be cognizant of this risk and take steps to avoid damage to the obturator nerve.
Obturator nerve block is used in the management of pain after lower limb surgery or for chronic hip pain. The anaesthetic is injected inferior to the pubic tubercle and lateral to the tendon of the adductor longus muscle. This procedure can also be carried out under ultrasound guidance.
Obturator nerve block is a safe and effective technique for managing acute and chronic pain in the medial compartment of the hip. It is important to note, however, that the procedure can cause further injury to the obturator nerve and should be done with due care and precision.
In conclusion, the obturator nerve provides motor and sensory function to the medial compartment of the thigh, and damage to it can cause serious complications. Careful attention should be paid to the obturator nerve during surgery and even during nerve blocks in order to avoid any further injury.
