L1 spinal nerve

Nervus spinalis L1

NervousNervesAbdomenLeft and right

View left in 3D View right in 3D

What it is
The L1 spinal nerve leaves the spinal canal between L1 and L2. 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 enters the lumbar plexus inside psoas.
Function
Carries motor fibres to the muscles of its segment (myotome) and sensation back from its strip of skin (dermatome): the groin and the inguinal region.
Size
About 2-3 mm thick; the mixed nerve is only ~1 cm long before it divides
Clinical note
Gives the iliohypogastric, ilioinguinal and genitofemoral nerves; the cremasteric reflex tests L1-L2.

Nearby nervous structures 10th intercostal nerve, 11th intercostal nerve, 9th intercostal nerve, Celiac plexus and ganglia, L2 spinal nerve, L3 spinal nerve, L4 dorsal root ganglion, L4 spinal nerve, L5 spinal nerve, Superior mesenteric plexus