Final answer:
The cervical plexus is formed by spinal nerves C1 through C5 and provides both motor and sensory innervation to areas of the neck and head; the number of cutaneous branches is not specified in the provided reference material.
Step-by-step explanation:
The cervical plexus consists of axons from the C1 through C5 spinal nerves and branches into various nerves that provide sensory and motor functions to the posterior neck and head, including the cutaneous branches. The exact number of cutaneous branches is variable and not explicitly stated in the provided reference material. However, it is known that these branches of the cervical plexus contribute to the innervation of the skin (cutaneous sensation) in these regions. The plexus also gives rise to the phrenic nerve, which is crucial for breathing as it innervates the diaphragm.