Introduction: the cervical plexus is a network of nerves
formed by the communications between the ventral rami of the superior four
cervical nerves (C1 to C4)
Relations: the plexus lies deep to the internal jugular vein
and the sternocleidomastoid muscles.
Branches:
Musclular:
1.      
Muscular branches are given off segmentally to
the prevertebral muscles (longus capitis, longus colli and the scalene)
2.      
A loop from C1 to the hypoglossal nerve.
3.      
Branches from C2 and C3 to sternocleidomastoid
4.      
The inferior root of the ansa cervicalis.
5.      
The phrenic nerve.
Cutaneous branches: these supply the front and sides of the
neck
1.      
The lesser occipital nerve (C2)
2.      
The great auricular nerve (C2, C3)
3.      
Transverse cervical nerve (C2, C3)
4.      
Supraclavicular nerve (C3, C4)
Clinical correlates: knife wounds and other wounds in the
neck may sever the superficial nerves in the posterior triangle resulting in
loss of cutaneous sensation in the neck.