The cervical plexus is a network of nerves located in the neck, formed by the anterior rami of the first four cervical spinal nerves, labeled as C1 to C4. It plays a crucial role in supplying sensory and motor functions to various structures in the neck, shoulders, and parts of the head. This plexus gives rise to several important nerves, including the phrenic nerve, which innervates the diaphragm, essential for breathing. Additionally, it provides sensory innervation to the skin of the neck and parts of the ear, contributing to the overall function and sensation in these areas.