Master CN IX with Picmonic for Physician Assistant

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Cranial Nerve Function

CN I

CN II

CN III

CN IV

CN IX

Brainstem with (9) Lollipop

Picmonic

CN IX is also known as the glossopharyngeal nerve. It is a motor and sensory nerve that has various functions including swallowing and taste sensation for the posterior 1/3 of the tongue. It is also important for regulation of heart rate via baroreceptors in the carotid sinus and regulation of respiratory drive via chemoreceptors in the carotid body.

8 KEY FACTS

The glossopharyngeal nerve travels through the jugular foramen. The solitary tract, which terminates in the solitary nucleus, transmits taste from the tongue and afferents from the carotid body and sinus. The nucleus ambiguus, which is actually a tract, transmits the motor functionality.

CN IX has visceral sensory (monitoring carotid body and sinus), general sensory (skin of the external ear etc) and special sensory functionality (taste sensation).

CN IX is responsible for taste sensation for the posterior 1/3 of the tongue via the foliate and circumvallate papillae.

CN IX innervates the carotid body (chemoreceptors) and the carotid sinus (baroreceptors). The chemoreceptors respond to decreased PO2 and increased PCO2 by increasing respiratory drive. The baroreceptors respond to pressure such that carotid massage leads to increased afferent baroreceptor firing and decreased heart rate. Carotid massage can be used to treat supraventricular tachycardia (SVT).

CN IX supplies the stylopharyngeus muscle which is responsible for the motor functions of swallowing and speech.

This muscle elevates the pharynx during swallowing and speech.

Can help evaluate CN IX by asking the patient to swallow a sip of water.

CN IX provides parasympathetic innervation to the parotid gland, which is responsible for salivation.

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