Home › Body Atlas › Nerves › Lumbar Plexus Overview

Lumbar Plexus Overview

plexus lumbalis (overview)

The lumbar plexus is formed within the substance of psoas major from the ventral rami of L1-L4, giving rise to the iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, and obturator nerves. The lumbosacral trunk (L4-L5) connects it to the sacral plexus.

Anatomical Data

Course & Distribution

Origin	Anterior rami of L1-L4, with a contribution from T12
Course	Forms within psoas major anterior to the lumbar transverse processes, its branches emerging from the lateral border, medial border and anterior surface of the muscle
Motor	Iliopsoas and quadratus lumborum (direct branches) Quadriceps femoris, sartorius and pectineus (femoral nerve) Adductor muscles and gracilis (obturator nerve) Lower internal oblique and transversus abdominis (iliohypogastric and ilioinguinal nerves) Cremaster (genitofemoral nerve)
Sensory	Lower abdominal wall, inguinal region and genitalia Anterior, lateral and medial thigh Medial leg and foot (saphenous nerve)

Clinical Relevance

Clinical Notes

The lumbar plexus within psoas is at risk during LLIF (lateral lumbar interbody fusion) procedures, where psoas retraction injures plexus branches producing post-operative hip flexor weakness, anterior thigh numbness, and groin pain. Neuromonitoring during LLIF guides safe retraction. The femoral nerve is the largest and most clinically significant lumbar plexus branch.

Pathology

Common Injuries & Conditions

Lumbar Plexus Injury in LLIF Surgery

Psoas retraction injury to the lumbar plexus during lateral lumbar interbody fusion producing anterior thigh numbness, hip flexor weakness, and groin pain, managed with neuromonitoring intraoperatively and physiotherapy post-operatively.

Explore

More in Lower Back

Browse all of Lower Back →