C4 spinal nerve

Nervus spinalis C4

NervousNervesNeckLeft and right

View left in 3D View right in 3D

What it is
The C4 spinal nerve leaves the spinal canal between C3 and C4. 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 cervical plexus.
Function
Carries motor fibres to the muscles of its segment (myotome) and sensation back from its strip of skin (dermatome): the base of the neck and the top of the shoulder.
Size
About 2-3 mm thick; the mixed nerve is only ~1 cm long before it divides
Clinical note
The main root of the phrenic nerve, which is why diaphragm irritation (e.g. a ruptured spleen) is felt as shoulder-tip pain.

Nearby nervous structures C2 spinal nerve, C3 spinal nerve, C5 spinal nerve, C6 dorsal root ganglion, C6 spinal nerve, C7 spinal nerve, C8 spinal nerve