Formed by the cartilaginous portion of the medial end of the eustachian tube. A mucosal prominence in the lateral aspect of the nasopharynx that protects the opening of the eustachian tube. Laterally: pharyngeal openings of the eustachian tube (connecting with the tympanic cavities), fossa of Rosenmueller, medial pterygoid plates, and superior pharyngeal constrictor muscles. Posteriorly: clivus, prevertebral musculature covering C1–C2. Extends from the base of the skull to the soft palate. Diseases that may affect the pharynx include infections ( pharyngitis, tonsillitis, diphtheria, infectious mononucleosis), sleep apnea, dysphagia, and pharyngeal cancer. The pharyngeal mucosa is lined by both stratified squamous epithelium and ciliated pseudostratified epithelium with goblet cells. Motor and sensory innervation are mainly via branches of the vagus and glossopharyngeal nerves. The lymphatics drain directly into the deep cervical nodes, either directly or through the retropharyngeal or paratracheal nodes. The pharyngeal veins drain into the internal jugular vein. The arterial supply is derived from branches of the external carotid artery, the ascending palatine and tonsillar branches of the facial artery, the maxillary artery, and the dorsal lingual branches of the lingual artery. The pharynx plays a role in deglutition, vocalization, and air conduction. from the uvula to the level of the hyoid bone), and the laryngopharynx (extending approx. from the base of the skull to the soft palate), the oropharynx (extending approx. It is divided into the nasopharynx (extending approx. 2C).The pharynx is a musculomembranous cavity that connects the oral and nasal cavities to the larynx and esophagus. No pharyngeal branches were found arising from the vagus nerve in this subject ( Fig. 1, cyan) and the recurrent laryngeal nerve ( Fig. 1B, green) and coursed along the posterior pharyngeal wall of the oro- and laryngopharynx and remained distinct from the internal laryngeal nerve ( Fig. This long pharyngeal variant of CN IX gave rise to a number of branches distributing to the mucosa and muscle wall ( Fig. However, after slipping between the superior and middle constrictor muscles, CN IX continued to descend between the pharyngeal mucosa and constrictor muscles all the way to the esophagus ( Fig. 1A, solid arrowhead) and motor branches to the stylopharyngeus muscle ( Fig. 1A, black arrowhead), the sinus nerve ( Fig. In this subject, CN IX gave rise to a slender branch directed superiorly towards the skull base (tympanic nerve Fig. CN IX emerged from the jugular foramen distinct from CN X ( Fig. The terminal, lingual branch that provides sensory innervation to the posterior one-third of the tongue.ĭuring dissection of the skull base exposing the jugular foramen and exit of CN IX–XII a peculiar innervation of the pharyngeal wall was discovered. Tonsillar branches that provide visceral sensory innervation to the palatine tonsil, soft palate and faucial pillars. Pharyngeal branches that join with pharyngeal branches from CN X. The carotid sinus nerve (of Herring) arises inferior to the petrosal ganglion and provides sensory innervation to the carotid body and sinus.Ī motor branch supplying the stylopharyngeus muscle. Post-synaptic neurons in the otic ganglion travel along the auriculotemporal nerve to distribute to the parotid gland. Along the superior aspect of the tympanic cavity, the tympanic plexus converges to form the lesser petrosal nerve which provides preganglionic parasympathetic innervation to the otic ganglion. The tympanic nerve (nerve of Jacobson) arises from the inferior ganglion, traverses the tympanic canaliculus and provides innervation to the middle ear cavity, mastoid air cells and auditory tube via the tympanic plexus. Axons reaching the rostral SN convey gustatory sense from the posterior one-third of the tongue those reaching more caudal SN relay visceral sensory information from the pharynx, middle ear, oral cavity and carotid sinus/body. 
Axons reaching the STN convey pain and thermal sense from the external ear. These primary sensory neurons project to the spinal trigeminal nucleus (STN) or solitary nuclei (SN).
Together, these sensory ganglia include pseudounipolar cell bodies that provide general somatic, visceral and special visceral innervation across the territory of CN IX. There are two sensory ganglia associated with CN IX: the superior and inferior (petrosal). The ISN provides preganglionic parasympathetic innervation to scattered ganglion cells in the tympanic cavity and otic ganglion. The NA includes lower motor neurons that provide innervation to the stylopharyngeus muscle. Efferent axons in CN IX are derived from the nucleus ambiguous (NA) and the inferior salivatory nucleus (ISN).
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