Nerves of the Head and Neck

Muscles and structures of the head and neck are innervated by either cranial nerves off of the brainstem or by nerves that arise from the cervical plexus.

                There are 12 cranial nerves that can be denoted by their name or by their number, always designated in Roman numerals and preceded with the upper case letters CN. These nerves all arise from the brainstem with the exception of CN I (the Olfactory nerve) which is actually a tract of the central nervous system and not a nerve at all. The 12 cranial nerves are:

                CN I                        Olfactory nerve

                CN II                       Optic nerve

                CN III                     Oculomotor nerve

                CN IV                     Trochlear nerve

                CN V                       Trigeminal nerve

                CN VI                     Abducens nerve

                CN VII                    Facial nerve

                CN VIII                   Vestibulocochlear nerve

                CN IX                     Glossopharyngeal nerve

                CN X                      Vagus nerve

                CN XI                     Spinal Accessory nerve

                CN XII                    Hypoglossal nerve

Nerves of the cervical plexus are easily divided into sensory or motor nerves. These nerves are:

                Sensory                                                 Motor

                                Lesser Occipital nerve                                         Nerve to Geniohyoid

                                Great Auricular nerve                                          Nerve to Thyrohyoid

                                Transverse Cervical nerve                                  Nerve to Superior Belly of Omohyoid

                                Supraclavicular nerves                                        Nerve to Inferior Belly of Omohyoid

                                                                                                                Nerve to sternothyroid

                                                                                                                Nerve to sternohyoid

                Note that the nerves to the superior and inferior bellies of the omohyoid muscle, sternohyoid muscle, and sternothyroid muscle all arise from a structure of the cervical plexus known as the ansa cervicalis which is further subdivided into the descendens hypoglossi and the descendens cervicalis

Other nerves arising from ventral rami of spinal nerves in the cervical region include the nerve to the Sternocleidomastoid muscle and nerves to the Trapezius and Levator scapulae muscles.