Anatomy #9. Rashed AL-Jomared. The Cranial Nerves IX. Amneh Hazaimeh & Alanood Bostanji

Transcription

1 Anatomy #9 The Cranial Nerves IX Rashed AL-Jomared Amneh Hazaimeh & Alanood Bostanji

2 السالم عليكم This lecture talks about the cranial nerves IX & X:: *Glossopharyngeal nerve : The nerve gets out of the brain as rootlet then it forms a single trunk, this happen lower down in the brainstem, the nerve comes out through jugular foramen then it forms two ganglion. Jugular foramen is formed by two bones { temporal and occipital} and there is a spine in it called jugular spine divide it into two compartments. These ganglions contain cell bodies of the sensory neuron,, then the branching process start! *glossopharyngeal nerve is sensory for inside of pharynx. ** a branch will go to the pharynx through Eustachian tube and to the middle ear supplying all the inside of tympanic membrane, mastoid air cell and Eustachian tube,, that's the tympanic branch of ninth nerve. It forms a plexus in the promontory < tympanic plexus>,, it will send a branch in petrous part of temporal bone called " lesser petrosal nerve".. *great petrosal nerve belongs to nerve VII. **parasympathetic fibers will leave and synapse in the otic ganglia and is going to supply parotid gland, *all other salivary glands supplied by facial nerve. Why we should learn this? Severe infection to the middle ear with svere inflammatory and chronic process will damage the tympanic plexus and reflected to the parotid gland losing it's blood supply,, so the patient will complain of slight dryness of mouth because there is another salivery glands.

3 # next branch has the main trunk goes in the neck in the carotid sheath and for a short distance it will leave the carotid sheath and going to supply one single muscle which is < stylopharyngeus>.. ** pharynx has two groups of muscles : 1** circular : the three constrictors.. 2**perpendicular: #stylopharyngeus.. #palatopharyngeus.. # salpingopharyngeus.. <<salpingopharyngeus is attached to Eustachian tube "" when we swallow we feel changing in pressure on both sides of tympanic membrane"".>> Conclusion: Glossopharyngeal nerve has : **parasympathetic nucleus that supply parotid gland. **motor nucleus that supply stylophayngeus muscle only. **the rest are sensory. # Sensation that are carried by glossophayngeal nerve: 1~ Common sensation: in posteror 1/3 of the tongue, pharynx, soft palate, palatine tonsils. << if u want to check the integrity of the glossopharyngeal nerve touch the soft palate or the wall of oropharynx sensation will go to the central nuclei and they come out through the vagus by " gag reflex" it's very very important because it can reflect the integrity of brain stem. 2~ Taste sensation (special) for posterior 1/3 of the tongue. 3~ baro receptors carotid sinus : Common carotid bifurcates into external and internal carotid arteries,, there is 2 systems: 1**a dilatation at the point of bifurcation or in many cases in internal carotid<< baro receptors>> these tiny nerve endings collect information about pressure and send them up through glossopharyngeus by carotid sinus nerve. 2** carotid body : it's not in the wall of internal or external or even the common carotid but it's located here

4 It has nerve endings that will test biochemistry. If u massage or press on carotid bifurcation > pressure sensation in baro receptors > nformation will go up > your brainstem will interpret that there's hypertension then send fibers to the heart through vagus nerve to slow the heart rate The carotid sinus is not something to play a round with,, BE CAREFULL! ****************** The doctor shows us a video about gag reflex : and here's some comments about the video : ** gaging is : initating of vomiting.. **why the doctor ask if the patient has tonsillitis?. Because glossopharyngeal nerve has tonsillar branch and if the tonsils are inflamed this will stimulate gag reflex, bringing it up a little bit below threshold. **any thing in the pharynx will stimulate gag reflex. **typical overactive gag reflex is one of the medical problem and it may need mesotherapy.. **testing of gag reflex is actually testing for : sensation that carried by nerve IX to the brain system,, and motor response through nerve X. *****************

5 * Here the Dr say a wrong information, about the deviation of Uvula if there is an injury in one of vagus nerves, but in the next lecture he correct it ; So I will mention the right information : The pharyngeal muscles PULL the Uvula, so if there is a lesion in the right Vagus, deviation of Uvula will be to the left(opposite) side. Let's go through the MM of Glossophayngeal nerve CN IX * See the Stylopharyngeus ; the only muscle of pharynx that supplied by CN IX * Look to Brown/orange rectangle at the lower-right side of MM - Baro- Receptor(Carotid sinus ) on the wall of internal Carotid artery, supplied by Carotid branch of glossopharyngeal. - Carotid body at the bifurcation of carotid artery. Due to these two systems ; Don't massage carotid bifurcation * CN IX has nuclei : 1- MOTOR nuclei " sup. Part of nucleus Ambiguus" : has a corticobulbar innervation from two cerebral cortex (cc- in MM ) " afferent neurons ". the motor efferent fibers will go & supply the stylopharyngeus muscle. NOTE : inf. Part of nucleus Ambiguous vagus nerve CN X 2- Parasympathatic nucleus " inf salivatory nucleus " : NOTE : Sup. Salivatory facial - this nucleus affected by :( afferent ) 1) Hypothalamus 2) Olfactory area 3) Taste cortical area - Efferent : * Tympanic branch will go to tympanic cavity & form tympanic plexus then the branch lesser petrosal otic ganglia parotid gland 3- Sensory nucleus " part of nucleus tractus Solitarius " : - it emerge in 3-4 Roots between olive & inferior cerebellar peduncle in the posterior cranial

6 fossa then through the Jugular foramen ; at this level it will form superior & inferior ganglia (sup. Ganglion is just a part /segment of inferior one ). - it's going to receive 1)taste sensation, 2)the branch that comes from Carotid body & sinus will end up in the dorsal nuclei of the vagus nerve. 3) common sensation(temp,pain,touch) from the post 1/3 of the tongue, pharynx,fauces & palatine tonsils inf ganglia sensory nucleus Let's go to the Vagus Nerve CN X : *at the jugular foramen the vagus is the neighbor of the glossopharyngeal. also we have two ganglia superior & inferior. * a little branch goes up called meningeal branch (also we have a meningeal branch from trigeminal nerve ) that supply the dura matter. * Vagus nerve give a branch that supply the auricle Don't over stimulate this nerve(around the external auditory meatus & a little branch to the tympanic membrane. if you Over stimulate this tympanic branch stimulate the parasympathetic pathway HR will decrease so much, can lead to death. * Vagus nerve has a very important connection with accessory nerve; because it also go out through the jugular foramen " well will talk about this connection later " * Pharyngeal branch "MOTOR" ; supply the constrictors + Soft palate *Soft palate taste buds Sensory *Gag Reflex :

7 -Afferent by glossopharyngeal (sensory ) Efferent by Vagus"pharyngeal branch" (Motor ) * Vagus will supply the Larynx (sensory & motor ) by the internal&external branches of the Superior laryngeal nerve & Recurrent laryngeal nerve(right & left branches). which are very important branches, because we can't live without opened airway. *In the neck vagus has Cardiac branch, because as you know the heart was developed just under the mandible control the HR of the heart by parasympathetic pathway. NOTE : until now we have group of nerves give parasympathetic branches : 1) oculomotor "3 rd " eye movement &, intraocular cilliary & iris muscles 2) Facial "7 th " all secretions from the face (eye, nose & mouth ) 3) "9 th " Parotid gland 4) Vagus "10 th " Heart + lungs + GI * Cough Reflex :" very important & protective mechanism for RS " sensation of something enters our trachea carried through the Vagus"Afferent" to the cough center in the brain Efferent by multiple nerves. - Physiology of cough : Expire greatly (so you need abdominal muscles + diaphragm + intercostal muscles ) to push the air out WITH closing of the glottis (need motor vagus) then you open the glottis things come out. *** Vagus nerve is the only Cranial nerve that enter the Thorax, supply the heart,lungs, esophagus. Then pass the diaphragm & supply the stomach. At the stomach level as you know that the stomach undergo rotation, So left & right vagus branches will become anterior & posterior. these will supply the Glands of the stomach (so if patient has hypersecretion of stomach acids, you should cut the vagus branch ) & there are so many plexuses "we will talke about them in parasympathetic lecture ". Then the vagus will continue to supply the rest of GI until the end of right two thirds of the transverse colon. note : left one third of T.colon will be innervated by parasympathetic branch of sacral nerve. Your colleagues : Amneh Hazaimeh & Alanood Albostanji GOOD LUCK