Lumbar Plexus

Lumbar Plexus

The lumbosacral plexus starts from L4 to S4. The lumbar plexus starts from L1 to L4. It has 6 branches. To remember this, think “I Twice Got Lunch on Friday”. Knee extension is done by muscles that are innervated by the L2, L3, and L4 nerve roots via the femoral nerve. The femoral nerve innervates the muscles of the anterior compartment of the thigh (quadriceps). ^th lumbar nerve root. All nerves except the genitofemoral nerve and the obturator nerve emerge from the lateral aspect of the psoas major muscle. The genitofemoral nerve emerges anteriorly, and the obturator nerve emerges medially in relationship to the psoas major muscle. L2, L3, and L4 will give the obturator and femoral nerves. The obturator nerve and the femoral nerve are equal.

The femoral nerve also provides sensation to this area. These muscles cause hip adduction: adductor brevis, adductor longus, and adductor magnus. They are innervated by the L2, L3, and L4 nerve roots via the obturator nerve. This is the area of sensation supplied by the obturator nerve. With its origin coming from the nerve roots of L2 and L3, the lateral femoral cutaneous nerve of the thigh innervates the skin on the lateral part of the thigh. Risk of injury to this nerve can occur with bone graft, with hip or acetabular procedures, and with external fixator of the pelvis. The genitofemoral nerve comes from the L1 and L2 nerve roots. Six branches come from the lumbar plexus. Two branches come from one nerve root. Two branches come from three nerve roots. Two branches come from two nerve roots. The two nerves that arise from one nerve root are: iliohypogastric and iliolinguinal. Both of these nerves arise from L1 nerve root. The iliohypogastric nerve is above the iliolinguinal nerve. The two nerves that arise from two nerve roots are the genitofemoral (L1, L2) and the lateral femoral cutaneous nerve of the thigh (L2, L3). The two nerves that arise from three nerve roots are the obturator and the femoral. Both arise from the L2, L3, and L4 nerve roots. There is also contribution from T12. The fourth lumbar nerve root also passes a branch to the lumbosacral trunk at the 5