CRANIAL NERVE IX: GLOSSOPHARYNGEAL NERVE

Five Functions of Glossopharyngeal Nerve:

• Innervates Stylopharyngeus Muscle.
• Special sense of taste to posterior 1/3 of tongue
• General sensation to posterior 1/3 of tongue, lateral oropharyngeal wall, part of soft palate
• Parasympathetic secretomotor to Parotid Gland
• Visceral Sensation from the Baroreceptors ("blood-pressure" receptors) at the Carotid Body (Sinus), at the bifurcation of the Carotids.

• These guys carry special chemoreceptors and stretch receptors. They provide feedback to the heart to control heart rate and modulate blood pressure.

TYMPANIC NERVE: Is given off at the Jugular Foramen from the Glossopharyngeal. It carries Parasympathetic innervation to the Parotid, via the Lesser Petrosal.

• It travels through the middle ear (inside the cranium), where it forms the Tympanic Plexus.
• It exits the cranium at the Lesser Petrosal Hiatus of the Temporal bone.
• After it exits back out, it is known as the Lesser Petrosal Nerve.
• Lesser Petrosal Nerve: The continuation of the Tympanic; it synapses at the Otic Ganglion and then continues to carry parasympathetic innervation to the Parotid Gland.

GAG REFLEX:

OVERALL PATH OF GLOSSOPHARYNGEUS TO PHARYNX:

• Through JUGULAR FORAMEN
• Down posterior wall of pharynx to innervate the stylopharyngeus muscle
• Penetrate gap between Superior and Middle Pharyngeal Constrictors, adhered to the Stylopharyngeus muscle.
• Finally, innervation to the posterior 1/3 of tongue.

Category: Anatomy Notes