L5 spinal nerve

Nervus spinalis L5

NervousNervesAbdomenLeft and right

View left in 3D View right in 3D

What it is
The L5 spinal nerve leaves the spinal canal between L5 and the sacrum. Its sensory (dorsal) and motor (ventral) roots meet just beyond the dorsal root ganglion; the short mixed nerve then splits into a small dorsal ramus for the back muscles and skin and a larger ventral ramus, which joins the sacral plexus.
Function
Carries motor fibres to the muscles of its segment (myotome) and sensation back from its strip of skin (dermatome): the lateral leg, top of the foot and the big toe.
Size
About 4-5 mm thick; the mixed nerve is only ~1 cm long before it divides
Clinical note
Test: big-toe extension; the L4/5 disc is one of the two commonest sites of sciatica and severe compression causes foot drop.

Nearby nervous structures 10th intercostal nerve, 11th intercostal nerve, Celiac plexus and ganglia, Enteric (myenteric) plexus - marker, L1 spinal nerve, L2 spinal nerve, L3 spinal nerve, L4 dorsal root ganglion, L4 spinal nerve, Superior mesenteric plexus