CRANIAL NERVE IX

THE GLOSSOPHARYNGEAL

NERVE

• It is a mixed nerve ,carrying both sensory and motor fibres.

• Nuclei:

Nucleus Ambiguus

Inferior Salivary Nucleus

Solitary Nucleus.

COURSE• It arises from the

medulla ,and then passes through the Jugular foramen of the skull ,between the IJV and the ICA.

• It is accompanied by Cranial nerves X and XI.

• It follows the ICA.

• It passes under the Styloid process ,and then into the pharynx ,where it lies over the Stylopharyngeus muscle and the middle pharyngeal constrictor muscle.

• It then passes undercover of the of the Hyoglossus muscle ,and is then distributed to the Palatine tonsil,and mucus memb of fauces,base of tongue ,and mucus glands of the mouth.

COMPONENTS OF THE GLOSSOPHARYNGEAL NERVE

• BRANCHIAL MOTOR COMPONENT:(SVE ) supplies the stylopharyngeus muscle.

• VISCERAL MOTOR COMPONENT: (GVE)parasympathetic innervation of smooth muscles and glands of pharynx and secretomotor to the parotid gland .

• VISCERAL SENSORY COMPONENT:(GVA)This innervates the baroreceptors of the carotid sinus,and the chemoreceptors of the carotid body.

GENERAL SENSORY COMPONENT:(GSA)carries pain, temp, and touch from skin of ext.ear,internal surface of tympanic memb.,upper pharynx and post.1/3rd of tongue.

SPECIAL SENSORY COMPONENT:(SA)

carrie taste sensation from the posterior 1/3rd of the tongue .

IMPORTANT BRANCHES

• The Tympanic br.to the tympanic plexus in the middle ear.

• Lesser petrosal N arises from this plexus and passes to the parotid gland.

• Carotid br,which carries sensory fibres .• Nerve to the Stylopharyngeus• Pharyngeal brs• Lingual br ,which supplies the post 1/3rd

of the tongue.

• C/C

The general sensory component mediates the afferent limb of pharyngeal reflex in which touching the back of the pharynx elicits the gag reflex . This is used to test the Glossopharyngeal nerve clinically.

CRANIAL NERVE XII

THE HYPOGLOSSAL NERVE

• Mainly motor

• Arises from the medulla

• Nucleus is the hypoglossal nucleus

FUNCTIONS

• It provides motor innervation to the muscles of the tongue except the Palatoglossus muscle which is innervated by the vagus nerve .

• It controls the shape and movements of the tongue.

• It is important for swallowing and articulation.

• It arises in the medulla.• It leaves the skull

through the hypoglossal canal.

• Descends in the neck with structures like the ICA ,IJV,and Vagus nerve.

• It then passes forwards on the side of the tongue

• It is joined in the upper part of its course by C1 fibres .

• The meningeal br.

• The descending br.

• Nerve to the Thyrohyoid muscle .

• Muscular brs to the muscles of the tongue.

• Nerve to the Geniohyoid muscle.

I

IMPORTANT BRANCHES

BRANCHES OF HYPOGLOSSAL

C/C:

• Paralysis of the Hypoglossal nerve will cause deviation of the tongue to the affected side .

• SO, to test the hypoglossal nerve , the patient is asked to stick out his tongue and then deviation ,if any, is noted by the weary and exhausted Medical Officer !!!

THE END !