glossopharyngeal nerve & its relation to vagus

GlossophyrangealNerve

&Its relation with

Vagus nerve

Amna liaqatRoll#51BDS3rd yr

Glossopharyngeal nerve It is the Ninth cranial nerveIt has three components:1. Motor2. Secretomotor parasympathetic3. sensory It has three nuclei:1. Main motor 2. Parasympathetic 3. Sensory

NUCLEI OFGLOSSOPHARYNGEAL NERVE:

1.Main motor nucleusLies deep in medulla oblongata.Receives afferent fibres from both cerebral hemispheres.Give efferent fibres to Stylopharyngeusmuscle.

2.Parasympathetic nucleusIt give preganglionic efferent fibres to1. Tympanic branch of 9th nerve2. Tympanic plexus 3. Lesser petrosal nerve The postganglionic fibres pass to Parotid salivary gland.

3.Sensory nucleus ofthe tractus solitariusGeneral sensation & taste sensationto posterior 3rd of tongue & pharynx.Afferent sensory fibres from the Carotid body & carotid sinus.

Course of Glossopharyngeal nerveEmerges from medulla oblongatab/w olives & inferior cerebellarPeduncle.Passes laterally in post. Cranial fossaLeave the skull by juglar foramenThan it passes to the lateral side ofneck & gives branches.

Juglar foramen

Branches ofGlossopharyngeal nerve1.Tympanic branchSensory supply to middle ear2.Lesser petrosal nerveSecretomotor fibres for Parotid salivaryGland3.Phyrangeal branchesForm pharyngeal plexus with vagal &Sympathetic fibres

4.Muscular branchesSupply to stylopharyngeus muscle5.Tonsillar branchesSupply tonsills & soft palate6.Lingual branchesSupply general & taste sensations toPost. third of tongue7.Carotid branchDescends on internal carotid artery& supplies the carotid body & carotidSinus.

Branches:

VAGUS NERVE:It is the 10th cranial nerveIt arises from the same area of brainas of the Glossophyrangeal nerveIt also exit through juglar foramenIt has two components1. Motor2. sensory

Vagus nerve has three nuclei: 1.Main motor nucleus Efferent fibres supply constrictor muscle of pharynx & intrinsic muscle of larynx. 2.Parasympathetic dorsal motor nucleus

Receives afferent fibres from 1.Hypothalmus 2.Glossopharyngeal nerve (from Carotid sinus & Carotid body)

It sends efferent fibres to involuntary muscles of bronchi,Heart,stomach,esophagus,small& large intestine.3.Sensory nucleusTaste sensations to epiglottis.

RELATIONSHIP B/WGLOSSOPHARYNGEAL &

VAGUS NERVE

CAROTID SINUS RELATIONS

CAROTID BODY RELATIONS

The glossopharyngeal & vagus nervesare related to each other through:

The carotid branch of 9th nerve carries the sensation of any change in blood pressure or in chemical constituents of blood fromCarotid body & carotid sinus throughafferent fibres.

Caroti d sinus refl ex

These afferent fibres reachparasympathetic dorsal motor nucleus of Vagus nerve.Vagus nerve inturn sends efferentFibres to the involuntary muscles of Heart,which in turn results in either ofthe following accordingly:BradycardiaHypotensionSyncopeasystole

All of these show the predominantParasympathetic effect of Vagus nerveon heart.

REFRENCES:CLINICAL NEUROANATOMY by Richard S.SnellB D Chayrasia’s HUMAN ANATOMYHead & Neck