Anatomy of the Lumbar and Obturator Nerves Quiz

Anatomy of the Lumbar and Obturator Nerves

• The lumbar plexus is a network of nerves that supplies the lower limb.
• It originates from the ventral rami of the four lumbar nerves (L1, L2, L3, L4).
• The lumbar plexus is located in the posterior abdominal wall in relation to the psoas major muscle.
• The lumbar plexus branches into several nerves that supply the anterior and medial sides of the thigh, lateral cutaneous nerve of the thigh, iliohypogastric nerve, ilioinguinal nerve, genitofemoral nerve, femoral nerve, and obturator nerve.
• The femoral nerve originates from the dorsal divisions of L2, L3, and L4 and terminates in the thigh by splitting into two divisions: anterior and posterior.
• The femoral nerve supplies motor branches to the quadriceps femoris, sartorius, and pectineus muscles and cutaneous sensory supply to the anterior and medial sides of the thigh, medial side of the leg, and medial side of the foot.
• Femoral nerve injury can cause paralysis of the quadriceps muscle and loss of sensation in the anterior and lower part of the medial aspects of the thigh, medial side of the leg, and medial side of the foot.
• The obturator nerve originates from the ventral divisions of L2, L3, and L4 and terminates by supplying the knee joint.
• The obturator nerve supplies motor branches to the obturator externus, adductor magnus, adductor longus, adductor brevis, pectineus, and gracilis muscles.
• Obturator nerve injury can cause paralysis of all adductor muscles and loss of sensation in a small area over the medial aspect of the thigh, except for the ischial part of the adductor magnus muscle.
• The lumbar plexus is distinct from the sacral plexus, which is a network of nerves that originates from the ventral rami of L4 and L5 and S1, S2, S3, and S4 spinal nerves.
• The sacral plexus is located on the posterior pelvic wall in front of the piriformis muscle and branches into nerves that supply the gluteal region and pass through the greater sciatic foramen.