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Glossopharyngeal Nerve

Nervus glossopharyngeus

For medical students2 min readUpdated 2026-10-10

The glossopharyngeal nerve is the 9th cranial nerve (CN IX) and possesses a mixed functional type. It provides general sensory and taste innervation to the posterior third of the tongue, innervates the stylopharyngeus muscle, carries secretomotor parasympathetic fibers, and participates in blood pressure regulation.

Fiber typesMixed: sensory, motor, parasympathetic
Skull exitAnterior part of the jugular foramen
Motor targetStylopharyngeus muscle only (*m. stylopharyngeus*)
Reflexogenic zoneCarotid sinus and carotid body (BP regulation)

Origin and Skull Exit

At the brainstem level, the glossopharyngeal nerve emerges from the medulla oblongata as 4–6 rootlets posterior to the olive, situated just inferior to the vestibulocochlear nerve (CN VIII).

The nerve leaves the cranial cavity via the anterior part of the jugular foramen. Right here, within the foramen region, two sensory ganglia form containing the cell bodies of sensory neurons:

From the skull base, the nerve descends between the internal carotid artery and internal jugular vein. It then curves forward and slightly upward to penetrate the root of the tongue.

Nuclei and Functional Composition

Being a mixed nerve, the glossopharyngeal nerve contains three types of fibers connected to different brainstem nuclei:

  1. Motor fibers. These are axons of somatic cells from the nucleus ambiguus. They supply a single muscle: the stylopharyngeus (m. stylopharyngeus).
  2. Sensory fibers. These are peripheral and central processes of cells from the superior and inferior ganglia. Their peripheral processes collect information from organs, while central processes enter the medulla oblongata to synapse in the nucleus of the solitary tract (tractus solitarius). Some also reach the upper part of the posterior nucleus of the vagus nerve.
  3. Parasympathetic (secretomotor) fibers. These originate from the autonomic inferior salivatory nucleus. Upon leaving the brain, they course into the tympanic nerve.

Main Branches of the Glossopharyngeal Nerve

Along its pathway, the nerve gives off several key branches supplying the pharynx, tongue, and vascular reflexogenic zones:

Tympanic Nerve and Its Pathway

The tympanic nerve (n. tympanicus) warrants special attention. It arises from the inferior ganglion and carries both sensory and parasympathetic fibers.

After entering the tympanic cavity of the middle ear, it runs along the medial wall, forming the tympanic plexus (plexus tympanicus) alongside sympathetic fibers from the caroticotympanic nerves. This plexus innervates the mucosa of the tympanic cavity, tympanic membrane, mastoid air cells, and sends a tubal branch to the pharyngotympanic (auditory) tube.

The continuation of the parasympathetic fibers from the tympanic plexus is the lesser petrosal nerve (n. petrosus minor). It exits the tympanic cavity, leaves the skull via the sphenopetrosal fissure, and heads toward the otic ganglion to provide its parasympathetic root.

Mnemonic

To remember the CN IX nuclei: motor is ambiguus (shared with the vagus nerve), parasympathetic is inferior salivatory, and sensory is the solitary tract.

Frequently asked questions

Where are the nuclei of the glossopharyngeal nerve projected on the rhomboid fossa?

The nuclei of the glossopharyngeal nerve project onto the superior triangle of the rhomboid fossa, located in the pons region.

In the topographical organization of the gray matter of the rhomboid fossa, the nuclei are arranged in functional columns:

  • Autonomic nuclei — occupy the intermediate column, lying between the somatic sensory and motor nuclei.
Which salivary gland do the parasympathetic fibers of the glossopharyngeal nerve innervate?

The parasympathetic fibers of the glossopharyngeal nerve innervate the parotid gland.

These efferent fibers follow this pathway:

  • Inferior salivatory nucleus (nucleus salivatorius inferior) — source of preganglionic fibers.
  • Lesser petrosal nerve (n. petrosus minor) — carries parasympathetic fibers to the relay site.
  • Otic ganglion (ganglion oticum) — parasympathetic ganglion where synapses occur before fibers proceed to the target organ.
Which nerves participate in the formation of the pharyngeal plexus?

The pharyngeal plexus (plexus nervosus pharyngis) is formed by contributions from cranial nerves and the autonomic nervous system.

Its contributors include:

  • Glossopharyngeal nerve (n. glossopharyngeus) — gives off 3–4 pharyngeal branches (rr. pharyngei) directed toward the lateral pharyngeal wall.
  • Vagus nerve (n. vagus) — contributes pharyngeal branches accompanying CN IX fibers.
  • Sympathetic trunk (truncus sympathicus) — fibers join the cranial nerve branches.
Where are the cell bodies of the glossopharyngeal nerve sensory neurons located?

In the superior and inferior ganglia (ganglion superius et inferius), which are located near the jugular foramen of the skull.

Which part of the tongue does CN IX innervate?

The posterior third of the tongue. The nerve transmits both general sensation and taste from the root of the tongue up to the vallate papillae.

What is the carotid sinus branch and what is its function?

It is a branch running to the carotid sinus and carotid body. It collects afferent impulses from baroreceptors and chemoreceptors, participating in the reflex regulation of blood pressure.

Where does the lesser petrosal nerve lead?

The lesser petrosal nerve, containing parasympathetic fibers from the tympanic plexus, leads to the otic ganglion.

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