Языкоглоточный нерв: анатомия, функции и клинические проявления.

Cranial nerve IX, for the tongue and pharynx

The glossopharyngeal nerve (,/ɡ//l//ɒ//s//oʊ//f//ə/'/r//ɪ//n//(//d//)//ʒ//i//ə//l//, // /,/f//ær//ən/'/dʒ//iː//ə//l/), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper medulla, just anterior (closer to the nose) to the vagus nerve. Being a mixed nerve (sensorimotor), it carries afferent sensory and efferent motor information. The motor division of the glossopharyngeal nerve is derived from the basal plate of the embryonic medulla oblongata, whereas the sensory division originates from the cranial neural crest.

From the anterior portion of the medulla oblongata, the glossopharyngeal nerve passes laterally across or below the flocculus, and leaves the skull through the central part of the jugular foramen. From the superior and inferior ganglia in jugular foramen, it has its own sheath of dura mater. The inferior ganglion on the inferior surface of petrous part of temporal is related with a triangular depression into which the aqueduct of cochlea opens. On the inferior side, the glossopharyngeal nerve is lateral and anterior to the vagus nerve and accessory nerve. In its passage through the foramen (with X and XI), the glossopharyngeal nerve passes between the internal jugular vein and internal carotid artery. It descends in front of the latter vessel and beneath the styloid process and the muscles connected with it, to the posterior lower border of the stylopharyngeus muscle. It then curves forward, forming an arch on the side of the neck and lying upon the stylopharyngeus and middle pharyngeal constrictor muscle. From there, it passes under cover of the hyoglossus muscle and is finally distributed to the palatine tonsil, the mucous membrane of the fauces and base of the tongue, and the serous glands of the mouth.

It receives general somatic sensory fibers (ventral trigeminothalamic tract) from the tonsils, the pharynx, the middle ear and the posterior 1/3 of the tongue. It receives special visceral sensory fibers (taste) from the posterior 1/3 of the tongue. It receives visceral sensory fibers from the carotid bodies, carotid sinus. It supplies parasympathetic fibers to the parotid gland via the otic ganglion. It supplies motor fibers to stylopharyngeus muscle, the only motor component of this cranial nerve. It contributes to the pharyngeal plexus.

Damage to the glossopharyngeal nerve can result in loss of taste sensation to the posterior one third of the tongue, and impaired swallowing.

The clinical tests used to determine if the glossopharyngeal nerve has been damaged include testing the gag reflex of the mouth, asking the patient to swallow or cough, and evaluating for speech impediments. The clinician may also test the posterior one third of the tongue with bitter and sour substances to evaluate for impairment of taste. The integrity of the glossopharyngeal nerve may be evaluated by testing the patient's general sensation and that of taste on the posterior third of the tongue. The gag reflex can also be used to evaluate the glossphyaryngeal nerve.