The Glossopharyngeal nerve is the 9 th cranial nerve and the only nerve that supplies the third branchial arch. It carries the taste and secretomotor fibers to the tongue, pharynx, and palate.
Nuclei
the glossopharyngeal nerve has three nuclei in the middle part of the medulla oblongata.
Nucleus ambiguous
Inferior salivatory nucleus
The nucleus of Tactus solitaries.
The Functional component of the Glossopharyngeal nerve
Special visceral afferent:
Fibers arise in the nucleus ambiguous and supply the stylopharyngeus muscle.
General Visceral Efferent:
They arise in the inferior salivatory nucleus and travels to the otic ganglion.
Postganglionic fibers supply the parotid glands.
General Visceral Afferent:
It is derived from the Peripheral Process of cells of the inferior ganglion.
They carry general sensation to the following:
pharynx
Carotid body
Carotid Sinus
these sensations are carried to the nucleus of the solitary tract
Special visceral afferents:
special visceral afferents are a part of the peripheral process of the inferior ganglion.
they carry taste sensations from the posterior one-third of the tongue including circumvallate papillae.
These sensations are conveyed to the nucleus of the solitary tract.
General Somatic Afferent:
These are the peripheral processes of the cell in the inferior ganglion.
they carry general sensation from the posterior one-third and the tonsil.
The course of Glossophyrangeal nerve
Intraneural course
fibers pass laterally between the olivary nucleus and the inferior cerebellar peduncle, through the reticular formation of nucleus.
Intracranial course
the filaments of the glossopharyngeal nerve unite to form a single trunk that passes through the jugular foramen
It is present in the middle of the jugular foramen anterior to the vagus and accessory nerve, it has its separate sheet of dura mater.
Extracranial course
the glossopharyngeal nerve descends between the internal jugular vein and the internal carotid artery.
In the neck, it passes between the internal carotid artery and the external carotid artery and moves laterally to reach the lateral part of the pharynx and gives pharyngeal branches.
Then it enters the submandibular region by passing into hyoglossus and gives tonsilar and lingual branches.
At the base of the skull the glossopharyngeal nerve has two ganglions: the superior ganglion and the inferior ganglion
Branches of the glossopharyngeal nerve
Tympanic nerve
It is a branch of inferior ganglion of the glossopharyngeal nerve enters middle ear through tympanic canaliculus and takes part in the formation of tympanic plexus
the tympanic plexus supplies the following:
Middle ear
Auditory tube
Mastoid antrum Air cells
The tympanic nerve also gives a branch called the lesser petrosal nerve.
the lesser Petrosal nerve gives preganglionic secretomotor fibers to the parotid gland through otic ganglion.
Carotid Branch
Descends down the internal carotid artery and supplies the carotid sinus and carotid body.
Pharyngeal Branches
takes part in the formation of pharyngeal plexus along with the vagus and sympathetic fibers.
The glossopharyngeal part of pharyngeal plexus supplies the mucous membrane of the pharynx.
Muscular Branch
The muscular branch of the glossopharyngeal nerve supplies the stylophyrangeus muscle.
the stylophyrangeus muscle prevents the collapse of the dorsal wall of pharynx.
Tonsillar branch
supplies tonsil.
joins the lesser palatine nerve to form a plexus, The fibrs of these plexus are distributed to the soft palate and the palatoglossal arch.
Lingual Branch
Carries taste and general sensation from the posterior one third of the tongue.
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