Lumbar plexus. Formation, position, branches.

lumbar plexus

- network of nerve fibres that supply skin & muscles of lower limb

- located within psoas major. is anterior to transverse process of lumbar vertebrae

- formed by anterior rami of spinal nerves T12-L5

- anterior rami of L1-L4 spinal roots divide into many cords. the cords combine together to form 6 major peripheral nerves of lumbar plexus

- then nerves descend down posterior abdominal wall to reach lower limb & innervate their target structures

7 branches of lumbar plexus

- iliohypogastric:

- ilioinguinal

- genitofemoral

- lateral femoral cutaneous

- obturator

- femoral

- lumbosacral

iliohypogastric nerve

- innervates internal oblique and transversus abdominis

- SENSORY FUNCTION: innervating posterolateral skin in gluteal region

ilioinguinal nerve

- innervates internal oblique and transversus abdominis

- SENSORY FUNCTION: innervating skin on superior anteromedial thigh

genitofemoral nerve

- genital branch innervates cremasteric muscle

- SENSORY FUNCTION: male branch innervates skin on anterior scrotum. femoral branch innervates skin on anterior upper thigh

lateral femoral cutaneous nerve

- no motor function

- innervates skin on anterior & lateral thigh down to knee

obturator nerve

- innervates medial thigh muscles

- innervates skin over medial thigh

femoral nerve

- innervates muscles in anterior thigh

- innervates skin on anterior & medial thigh