Lateral femoral cutaneous nerve

The lateral femoral cutaneous nerve of the thigh is a sensory nerve responsible for providing cutaneous innervation to the skin of the lateral thigh.

Origin

The nerve originates from the posterior divisions of the anterior rami of the L2 and L3 lumbar spinal nerves within the lumbar plexus.

Course

• The nerve emerges from the lateral border of the psoas major muscle.

• It travels obliquely downward across the iliacus muscle, lying deep to the iliacus fascia.

• It passes underneath the inguinal ligament, just medial to the anterior superior iliac spine (ASIS), to enter the thigh.

• Once in the thigh, the nerve traverses over the sartorius muscle, lying on its anterior surface while remaining deep to the fascia lata.

Branches

The lateral femoral cutaneous nerve divides into anterior and posterior branches at the level of the lateral thigh, deep to the fascia lata:

a) Anterior branch

Contains primarily L3 fibers. Its terminal branches supply the anterior and lateral parts of the skin of the thigh. Some of these fibers contribute to the pre-patellar plexus (in conjunction with the infrapatellar branch of the saphenous nerve).

b) Posterior branch

Contains primarily L2 fibers. Its terminal branches supply the lateral and posterior parts of the skin of the thigh.

Function

The lateral femoral cutaneous nerve is a pure sensory nerve, containing only somatic afferent (sensory) fibers. It provides sensory innervation to the skin of the anterior and posterior aspects of the lateral thigh, extending down to the region just above the knee. The somatic afferent fibers travel back to the lumbar plexus, with L2 fibers (from the posterior branch) reaching the second lumbar segment of the spinal cord, while L3 fibers (from the anterior branch) reach the third lumbar segment.

Clinical Relevance: Meralgia Paresthetica

The nerve is clinically significant as compression or entrapment of the lateral femoral cutaneous nerve (commonly at its passage under the inguinal ligament) can cause meralgia paresthetica. This condition manifests as pain, tingling, numbness, or burning sensations over the lateral thigh.