The cervical plexus can be seen as a cluster of nerves originating from the anterior rami of spinal nerves C1-C4. A nerve loop known as the ansa cervicalis is formed by branches of spinal nerves C1-C3 can be seen in the superior aspect of the illustration. The ansa cervicalis gives off several motor branches to the infrahyoid muscles. The phrenic nerve originates from C3-C5. It travels into the thoracic cavity and provides motor innervation to the diaphragm and sensory supply to the pericardium and diaphragm. The cervical plexus also provides contributions to the accessory nerve, innervating the trapezius muscle. The superficial/cutaneous branches of the cervical plexus (lesser occipital, great auricular, transverse cervical and supraclavicular nerves) innervate the skin of the neck, scalp and shoulder.
