It is the Ninth cranial nerveIt has three components:1. Motor2. Secretomotor parasympathetic3. sensory It has three nuclei:1. Main motor2. Parasympathetic3. Sensory
1.Main motor nucleusLies deep in medulla oblongata.Receives afferent fibres from bothcerebral hemispheres.Give efferent fibres to Stylopharyngeusmuscle.
2.Parasympathetic nucleusIt give preganglionic efferent fibres to1. Tympanic branch of 9th nerve2. Tympanic plexus3. Lesser petrosal nerve The postganglionic fibres pass toParotid salivary gland.
3.Sensory nucleus ofthe tractus solitariusGeneral sensation & taste sensationto posterior 3rd of tongue & pharynx.Afferent sensory fibres from theCarotid body & carotid sinus.
Emerges 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.
1.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.
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 nucleusEfferent fibres supply constrictormuscle of pharynx & intrinsic muscleof larynx.2.Parasympathetic dorsal motor nucleusReceives afferent fibres from1.Hypothalmus2.Glossopharyngeal nerve(from Carotid sinus & Carotid body)
It sends efferent fibres toinvoluntary muscles of bronchi,Heart,stomach,esophagus,small& large intestine.3.Sensory nucleusTaste sensations to epiglottis.
The glossopharyngeal & vagus nervesare related to each other through:The carotid branch of 9th nervecarries the sensation of anychange in blood pressure or inchemical constituents of blood fromCarotid body & carotid sinus throughafferent fibres.
These afferent fibres reachparasympathetic dorsal motornucleus of Vagus nerve.Vagus nerve inturn sends efferentFibres to the involuntary muscles ofHeart,which in turn results in either ofthe following accordingly:BradycardiaHypotensionSyncopeasystole
All of these show the predominantParasympathetic effect of Vagus nerveon heart.
CLINICAL NEUROANATOMY byRichard S.SnellB D Chayrasia’s HUMAN ANATOMYHead & Neck