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Ix nerve


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IX cranial Nerve

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Ix nerve

  1. 1. The Glossopharyngeal NervePLAYFigure 14.27
  2. 2. Glossopharyngeal• Fibers emerge from the medulla, leave the skullvia the jugular foramen, and run to the throat• Nerve IX is a mixed nerve with motor and sensoryfunctions• Motor – innervates part of the tongue andpharynx, and provides motor fibers to the parotidsalivary gland• Sensory – fibers conduct taste and generalsensory impulses from the tongue and pharynx
  3. 3. Glossopharyngeal nerve• Leave the skull through jugularforamen• Passes forwards betweeninternal jugular vein andexternal carotid artery.• Deep to styloid process.• Between external and internalcarotid arteries at posteriorborder of stylopharyngeus thenlateral to it.• Reaches the pharynx by passingbetween middle and inferiorconstrictor, deep to hyoglossus,where it breaks into terminalbranches.•
  4. 4. Glossopharyngeal Nerve• A mixed nerve (sensory,motor, parasympathetic)• Emerges from the ventralsurface of the medullaoblongata• Runs laterally in theposterior cranial fossa• Leaves the skull by passingthrough the central part ofthe jugular foramen• Has superior and inferiorganglia, that are locatedwithin the jugular foramen.
  5. 5. • At its exit from the skull, itpasses forward between theinternal jugular vein andinternal carotid artery,within the carotid sheath• Descends to the lowerborder of thestylopharyngeus muscle.• Then curves forward aroundthe stylopharyngeus and• Passes through the gapbetween the superior andmiddle constrictor musclesof the pharynx
  6. 6. • Passes under cover ofthe hyoglossus muscle• Distributed to the: Palatine tonsil Mucous membrane ofthe fauces and baseof the tongue, Mucous glands of themouth PFTPT
  7. 7. Gloosopharyngeal nerve• jf--jugular foramen• sg--superior ganglion• ig--inferior ganglion• tp--tympanic plexus• lpn--lesser petrosal nerve• fo--foramen ovale• og--otic ganglion• pg--parotid gland• sp--nerve tostylopharyngeus muscle• pb--pharyngeal branch• ncbcs--nerve to carotidbody carotid sinus• Red solid -- motor• Red dotted --parasympathetic• Yellow -- sensory (afferent)
  8. 8. Glossopharyngeal nerve• Ganglia• Superior ganglionsmall, with nobranches.• Inferior ganglion, largecarries generalsensations frompharynx, soft palateand fauces.
  9. 9. Nerve IX: Glossopharyngeal
  10. 10. Detail on Glossopharyngeal (IX) Function:•Motor to stylopharyngeus muscle.•Parasympathetic secretomotor fibers to parotidgland.•Sensory to pharynx, tonsils, and posterior 1/3 oftongue.•Taste fibers for posterior 1/3 of tongue.
  11. 11. Glossopharyngeal Nerve (IX)• Innervates structures of the tongue andpharynxTable 14.3 (9 of 12)Facial nerve (VII)Vestibulocochlearnerve (VIII)Glossopharyngealnerve (IX)Vagus nerve (X)Accessory nerve (XI)Hypoglossal nerve (XII)
  12. 12. COURSE• It arises from themedulla ,and thenpasses through theJugular foramen ofthe skull ,betweenthe IJV and the ICA.• It is accompanied byCranial nerves X andXI.• It follows the ICA.
  13. 13. • It passes under the Styloid process ,andthen into the pharynx ,where it lies overthe Stylopharyngeus muscle and themiddle pharyngeal constrictor muscle.• It then passes undercover of the of theHyoglossus muscle ,and is thendistributed to the Palatine tonsil,andmucus memb of fauces,base of tongue,and mucus glands of the mouth.
  14. 14. 1. The glossopharyngeal nerve arises by 4-5 rootlets from theposterolateral sulcus of medulla.2. It leaves the skull through the jugular foramen.3. While it lies in jugular foramen it has 2 small sensory ganglia (superiorand inferior).4. It descends downwards inside the upper carotid sheath superficial tovagus nerve and between IJV & ICA lying deep to the styloid processand muscle attached to it.5. Then it leaves the carotid sheath and passes forwards withstylopharyngeus muscle between the ICA & ECA.6. Ascends deep to hyoglossus to reach the tongue.Termination: it ends into terminal branches supplying the mucousmembranes of pharynx, tonsil and the posterior 1/3 of tongue.Course of Glossopharyngeal Nerve
  15. 15. IX : Glossopharyngeal Nerve :Glossopharyngeal nerve nuclei & theircentral connectionsIt is a mixed N. ,attachedlateral to olive in rostralmedulla and leaves the skullthrough jugular foramen.It receives afferent Fs. From :1-Receptors of general sensationin pharynx, post.1/3 of tongue,eustachian tube & middle ear.2- Taste buds of pharynx &post.1/3 of tongue.3- Chemoreceptors in carotidbody & Baroreceptors in thecarotid sinus.
  16. 16. 1. Meningeal branch (sensory): Arises from the intracranial part of the glossopharyngealnerve. Sensory nerve supplies meninges of posterior cranialfossa.Branches of the Glossopharyngeal Nerve
  17. 17. 2. Tympanic branch (Jacobsons Nerve- parasympathetic nerve): Preganglionic parasympathetic nerve to parotid gland. Arises from the inferior ganglion of the glossopharyngeal nerve inthe jugular fossa.Course of the tympanic nerve: It passes through the tympanic canaliculus. It reaches the middle ear cavity where it breaks to form thetympanic plexus. Lesser superficial petrosal nerve arises from the tympanic plexusand reaches the middle cranial fossa. Then lesser superficial petrosal nerve passes through the foramenovale to reach infratemporal fossa to relay in the otic ganglion. The postganglionic fibers joint the auriculotemporal to supply theparotid gland.Branches of the Glossopharyngeal Nerve
  18. 18. 3. Carotid branch (sensory): sensory nerve to thecarotid sinus and carotid body.4. Nerve to stylopharyngeus muscle (motor):motor nerve to stylopharyngeus muscle.Branches of the Glossopharyngeal Nerve
  19. 19. 5. Pharyngeal branches (sensory): they enter theformation of the pharyngeal plexus and suppliesthe mucous membrane of pharynx.The pharyngeal plexus receives also:a. Motor fibers (the pharyngeal branches ofvagus nerve).b. Sympathetic fibers(the pharyngeal branchesof the superior cervical ganglion)Branches of the Glossopharyngeal Nerve
  20. 20. 6. Tonsillar branches (sensory): to the palatine tonsil.7. Lingual branches (sensory): terminal branches tomucous membrane of the posterior 1/3 rd of the tongue(taste and general sensation).Branches of the Glossopharyngeal Nerve
  21. 21. Branches• Tympanic branch: Passes to thetympanic plexus in the middle earand: Supplies sensory fibers to theplexus Carries preganglionicparasympathetic fibers, thatleave the plexus as lesserpetrosal nerve and synapse inthe otic ganglion• Carotid branch: carries sensoryfibers from the carotid sinus &carotid body• Muscular branch to thestylopharyngeus muscle
  22. 22. Branches cont’d• Lingual branch: passes to theposterior third of the tongueand the circumvellatepapillae• Pharyngeal branches: carrysensory fibers to thepharyngeal plexus, whichsupplies the mucousmembrane of the pharynx,tonsil and soft palate• Communicates with the:• Vagus & facial nerves• Superior cervical ganglionof the sympathetic chain
  23. 23. Branches.• Of communications:• Inferior ganglion and• superior cervicalsympathetic ganglion.• Superior ganglion andauricular branch ofvagus.• Its trunk and facial nerveat stylomastoid foramen
  24. 24. Branches.• Of distribution:• Tympanic.• Stylopharyngeus.• Pharyngeal.• Tonsillar.• Lingual .
  25. 25. IMPORTANT BRANCHES• The Tympanic the tympanic plexus in themiddle ear.• Lesser petrosal N arises from this plexus andpasses 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 thetongue.
  26. 26. • C/CThe general sensory component mediates theafferent limb of pharyngeal reflex in whichtouching the back of the pharynx elicits thegag reflex . This is used to test theGlossopharyngeal nerve clinically.
  27. 27. IX : Glossopharyngeal Nerve Fibres :Glossopharyngeal nerve nuclei &their central connections. Red= motor,brown=parasymp.,blue=sensory1-Afferent Fs. for generalsensation : end in trigeminalsensory nucleus.-Fibres carrying touch sensationfrom back of tongue +pharynxare important for mediating gagreflex, through connection withnucleus ambiguus & hypoglossalnucleus.2-Afferent visceral (chemo-&baroreceptors) & taste Fs. :end in nucleus solitarius ofmedulla.
  28. 28. IX : Glossopharyngeal Nerve Fibres :Glossopharyngeal nerve nuclei &their central connections. Red= motor,brown=parasymp.,blue=sensory3-Efferent motor Fibres :arises from its motor nucleus in therostral part of nucleus ambiguus ofmedulla to supply stylopharyngeusinvolved in swallowing.4-Efferent ParasympatheticFibres : arises from inferiorsalivary nucleus of rostral medullato synapse in otic ganglion, then viapost-ganglionic Fs.innervate parotidgland.
  29. 29. 1. Nucleus ambiguus (SVE)• Branchial motor to stylopharyngeus2. Inferior salivary nucleus (GVE)• to parotid gland (via otic ganglion)
  30. 30. 3. Spinal trigeminal nucleus• Somatic sensory from outer ear (superiorganglion of IX)4. Nucleus of the solitary tract• Visceral sensory from carotid body and sinus,mucosa of pharynx, posterior tongue, middle ear(inferior ganglion of IX)• Visceral sensory from taste buds on posterior thirdof tongue (inferior ganglion of IX)
  31. 31. Glossopharyngeal nerve (Ⅸ)Components of fibers• SVE fibers: originate from nucleus ambiguus, and supplystylopharygeus• GVE fibers: arise from inferior salivatory nucleus and ralyed in oticganglion, the postganglionic fibers supply parotid gland• SVA fibers: arise from the cells of inferior ganglion, the centralprocesses of these cells terminate in nucleus of solitary tract, theperipheral processes supply the taste buds on posterior third oftongue• GVA fibers: visceral sensation from mucosa of posterior third oftongue, pharynx, auditory tube and tympanic cavity, carotid sinusand glomus, and end by synapsing with cells of nucleus of solitarytract• GSA fibers: sensation from skin of posterior surface of auricle and
  32. 32. Course: leaves the skull via jugular foramenBranches• Lingual branches : to taste buds and mucosa of posterior third of tongue• Pharyngeal branches : take part in forming the pharyngeal plexus• Tympanic nerve : GVE fibers via tympanic and lesser petrosal nerves tootic ganglion, with postganglionic fibers via auriculotemporal (Ⅴ3) toparotid gland• Carotid sinus branch : innervations to both carotid sinus and glomus• Others: tonsillar and stylophayngeal branchesOtic ganglion: situated just below foramen ovale
  33. 33. Glossopharyngeal Nerve• Modalities:SVM:From:Nucleus ambiguous.To:Stylopharyngeus.
  34. 34. Glossopharyngeal Nerve• Modalities:GVS:From:Carotid body.Carotid sinus.
  35. 35. Glossopharyngeal Nerve• Modalities:GVM:Preganglionics:From:Inferior salivatory nucleus.To:Otic ganglion.Postganglionics:To:Parotid gland.
  36. 36. Glossopharyngeal Nerve• Modalities:GSS:From:Posterior 1/3 of tongue.External ear.Middle ear cavity.
  37. 37. Glossopharyngeal Nerve• Modalities:SVS:From:Posterior 1/3 of tongue (taste).
  38. 38. Functions• Receives general sensory fibers from the posterior⅓ of the tongue, tonsil, pharynx, middle ear andcarotid sinus.• Receives special sensory (taste) fibers from theposterior ⅓ of the tongue and the circumvellatepapillae• Supplies parasympathetic fibres to the parotidgland via the otic ganglion• Supplies motor fibers to stylopharygeus muscle• Contributes sensory fibers to the pharyngeal plexus
  39. 39. Table 13.2
  40. 40. Cranial nervesGlossopharyngeal Nerve (CN IX)Functions: Sensory (general somatic afferent, special visceral afferent, general visceral afferent), motor (specialvisceral efferent), and parasympathetic (general visceral efferent) for derivatives of the 3rd pharyngeal arch.Nuclei: Four nuclei in the medulla send or receive fibers via CN IX: two motor and two sensory. Three of thesenuclei are shared with CN X.The glossopharyngeal nerve (CN IX) emerges from the lateral aspect of the medulla and passes anterolaterally toleave the cranium through the anterior aspect of the jugular. At this foramen are superior and inferior (sensory)ganglia, which contain the pseudounipolar cell bodies for the afferent components of the nerve. CN IX follows thestylopharyngeus, the only muscle the nerve supplies, and passes between the superior and the middle constrictormuscles of the pharynx to reach the oropharynx and tongue. It contributes sensory fibers to the pharyngeal plexusof nerves.CN IX is afferent from the tongue and pharynx (hence its name) and efferent to the stylopharyngeus and parotidgland.Branchial Motor Motor fibers pass to one muscle, the stylopharyngeus, derived from the 3rd pharyngeal arch.Parasympathetic (Visceral Motor)Following a circuitous route initially involving the tympanic nerve, presynaptic parasympathetic fibers are providedto the otic ganglion for innervation of the parotid gland. The otic ganglion is associated with the mandibular nerve(CN V3), branches of which convey the postsynaptic parasympathetic fibers to the parotid gland .Sensory (General Sensory)The general sensory branches of CN IX are as follows : The tympanic nerve. The carotid sinus nerve to the carotidsinus, a baro- (presso) receptor sensitive to changes in blood pressure, and the carotid body, a chemoreceptorsensitive to blood gas (oxygen and carbon dioxide levels).The pharyngeal, tonsillar, and lingual nerves to the mucosa of the oropharynx and isthmus of the fauces (L. throat),including palatine tonsil, soft palate, and posterior third of the tongue. In addition to general sensation (touch, pain,temperature), tactile (actual or threatened) stimuli determined to be unusual or unpleasant here may evoke the gagreflex or even vomiting.Taste (Special Sensory) Taste fibers are conveyed from the posterior third of the tongue to the sensory ganglia.
  41. 41. Lesion of the Glossopharyngeal Nerve:1. Loss of taste and general sensation from the posterior1/3 of the tongue.2. Loss of sensation in the pharynx.3. Some pharyngeal weakness.4. Loss of salivation from the parotid gland.
  42. 42. Glossopharyngeal Nerve Lesions• Glossopharyngeal nerve lesionsproduce: Difficulty in swallowing Loss of general sensation over theposterior one-third of the tongue,palate, and pharynx Loss of taste sensation over theposterior one-third of the tongueand palate Dysfunction of the parotid gland Loss of the gag reflex
  43. 43.  The glossopharyngeal nerve is a mixed nerve containing:a. Sensory fibers.b. Parasympathetic fibersc. Motor fibers. It is more important as sensory than as a motor nerve.Origin: from posterolateral sulcus of medulla.The Glossopharyngeal Nerve (IX)
  44. 44. It has three nuclei:1. The upper part of nucleus ambiguous: it lies in the medulla (motorfunction).2. The inferior salivary nucleus: it lies in the medulla (parasympatheticfunction).3. The solitary nucleus: it lies in the medulla (sensory function).Nuclei of Glossopharyngeal Nerve
  45. 45. IX: GLOSSOPHARYNGEAL• carries information from the head and neck to thebrainstem.• Information about blood pressure (baroreceptors)
  46. 46. CN IX: glossopharyngeal nerve
  47. 47. CN IX and X