Glossopharyngeal nerve

The glossopharyngeal nerve (IX) is a mixed cranial nerve carrying sensory, motor, taste, and parasympathetic fibers. It provides sensory innervation to the caudal part of the tongue, pharyngeal mucosa, and carotid sinus, carries taste from the caudal third of the tongue, and contributes motor and parasympathetic innervation to pharyngeal and salivary structures.

Number : IX

Sensory, motor, or both : both

Origin : it emerges from the lateral aspect of the medulla oblongata, just caudal to the vestibulocochlear nerve. Its motor fibers arise from the rostral portion of the nucleus ambiguus, and its parasympathetic fibers arise from the parasympathetic nucleus of the glossopharyngeal nerve.

Route / Reports : the nerve leaves the cranial cavity through the jugular foramen and the tympanooccipital fissure together with the vagus and accessory nerves. Outside the skull, it passes medially to the cranial cervical sympathetic ganglion and gives off tympanic, carotid sinus, stylopharyngeal, tonsillar, pharyngeal, and lingual branches.

Distribution : sensory fibers supply the caudal third of the tongue, pharynx, and carotid sinus; taste fibers supply the vallate and foliate papillae; motor fibers innervate the stylopharyngeus and contribute with the vagus to pharyngeal musculature; parasympathetic fibers reach the parotid and zygomatic salivary glands via the tympanic nerve, minor petrosal nerve, otic ganglion, and auriculotemporal nerve.

Description : The glossopharyngeal nerve originates from the lateral medulla oblongata and exits the skull through the jugular foramen and tympanooccipital fissure. It then distributes sensory fibers to the pharynx, carotid sinus, and caudal third of the tongue, carries taste from the caudal tongue, provides motor fibers to the stylopharyngeus and pharyngeal muscles, and sends parasympathetic fibers toward the parotid and zygomatic salivary glands.