Anatomy Essentials

• The glossopharyngeal nerve (CN IX) emerges from the medulla as a series of rootlets between the olive and the inferior cerebellar peduncle. These rootlets converge to form the glossopharyngeal nerve. In the jugular fossa, the tympanic nerve is given off. The nerve then exits the skull through the jugular foramen and gives off branches which supply motor fibers to the stylopharyngeus muscle, visceral motor input to the parotid gland, sensation from the carotid body and sinus, general sensory from the posterior one third of the tongue, pharyngeal mucosa, skin of the external ear and tympanic membrane, and taste from the posterior one third of the tongue.
• The vagus nerve (CN X) emerges from the medulla as several rootlets. These rootlets converge into roots that exit the skull through the jugular foramen. As it continues beyond its two sensory ganglia (jugular and nodosum) it is joined by fibers of the nucleus ambigus that have traveled briefly with the cranial root of XI. In the neck the vagus lies between the internal jugular vein and the internal carotid artery, descending within the carotid sheath. The nerve branches to innervate: the striated muscles of the pharynx and larynx (except stylopharyngeus [IX] and tensor veli palatini [V]), smooth muscle and glands of the pharynx, larynx, thoracic and abdominal viscera, sensory from the thoracic and abdominal viscera, and sensory from the external ear, external auditory meatus and tympanic membrane.