Lumbar plexus

The lumbar plexus is a complex neural network formed by the lower thoracic and lumbar ventral nerve roots (T12 to L5) which supplies motor and sensory innervation to the lower limb and pelvic girdle.

Summary

• origin: ventral rami of T12 to L5
• course: formed within the substance of the psoas major muscle, anterior to the lumbar transverse processes
• major (terminal) branches
  • ​Iliohypogastric nerve
  • ilioinguinal nerve
  • genitofemoral nerve
  • lateral femoral cutaneous nerve
  • femoral nerve
  • obturator nerve
• motor supply: lower limb and pelvic girdle
• sensory supply: lower anterior abdominal wall, groin, upper thigh and pudenda

Gross anatomy

The branches that arise from the lumbar plexus are:

• subcostal nerve: T12
• Iliohypogastric nerve: L1
• ilioinguinal nerve: L1
• genitofemoral nerve: L1, 2
• lateral femoral cutaneous nerve: L2, 3
• femoral nerve: L2, 3, 4
• obturator nerve: L2, 3, 4
• lumbosacral trunk: L4, 5
  • this contributes to the sacral plexus

The branches of the lumber plexus are covered in this mnemonic.

Variant anatomy

Variation in the lumbar plexus appears to be common (~90% in one study) :

• absent iliohypogastric nerve (~20%)
• early branching (within psoas muscle) of the genitofemoral nerve (~20%)
• accessory obturator nerve (~10%)
• lateral femoral cutaneous nerve arising as a branch of the femoral nerve

Siehe auch:

• lumbar plexus block
• sacral nerve plexus - posterior components (mnemonic)

und weiter:

• Triton-Tumor