Cranial 9th & 10th

Neuroanatomy block-Anatomy-Lecture 8

Editing file Objectives

At the end of the lecture, students should be able to:

● Define the deep origin of both Glossopharyngeal and Vagus Nerves. ● Locate the exit of each from the brain stem. ● Describe the course and distribution of each nerve . ● List the branches of both nerves.

Color guide

● Only in boys slides in Green ● Only in girls slides in Purple ● important in Red ● Notes in Grey Glossopharyngeal (IX) 9th Cranial Nerve

● it's mixed nerve, a Sensory nerve with preganglionic parasympathetic and few motor fibers ● It has no real nucleus to itself. Instead it shares nuclei with VII (facial) and X (vagus).

Superficial attachment Course

● It arises from the ventral aspect of the 1. It Passes forwards between medulla by a linear series of small Internal jugular vein and rootlets, in groove between olive and External carotid artery. inferior cerebellar peduncle. ● It leaves the cranial cavity by passing 2. Lies Deep to Styloid process. through the jugular foramen in company with the Vagus , and the Accessory 3. Passes between external and nerves and the Internal jugular vein. internal carotid arteries at the posterior border of Stylopharyngeus then lateral to it.

4. It reaches the pharynx by passing between middle and inferior constrictors, deep to Hyoglossus, where it breaks into terminal branches.

3 Glossopharyngeal (IX) 9th Cranial Nerve

Ganglia & Communications

● Small with no branches. Superior Ganglion ● It is connected to the Superior Cervical sympathetic ganglion.

● Large and carries general sensations from pharynx, soft palate and tonsil. Inferior ● ganglion It is connected to Auricular Branch of Vagus.

● The Trunk of the nerve is connected to the at the stylomastoid foramen.

4 Glossopharyngeal (IX) 9th Cranial Nerve

Component of fibers & Deep origin

Type of fibers Nuclei Structure innervated

SVE fibers: Supply stylopharyngeus muscle. Special Visceral (NA) Efferent

GVE fibers: inferior salivatory Relay in otic ganglion. General Visceral nucleus (ISN). the postganglionic fibers supply Efferent .

SVA fibers: Nucleus of solitary Originate from the cells of inferior Special Visceral tract (NST). ganglion, their Afferent 1- Central processes terminate in (NST). 2-Peripheral processes carry sensation from the taste buds on posterior third of tongue.

GVA fibers: Nucleus of solitary Carry visceral sensation from mucosa General Visceral tract (NST). of posterior third of tongue, pharynx, Afferent auditory tube ,tympanic cavity and carotid sinus.

Note: It's important to differentiate between sensation from mucosa which is general sensation and sensation from taste buds which is special sensation

5 Glossopharyngeal (IX) 9th Cranial Nerve

BRANCHES & Nerve lesion

Tympanic: (sensory + para sym) relays in the otic ganglion and gives Pharyngeal: to the mucosa of secretomotor to the parotid gland pharynx .

Nerve to Stylopharyngeus muscle. The only motor branch Tonsillar (sensory) Branches Lingual : carries sensory branches, general and special (taste) from the posterior third of the Sensory branches from the carotid tongue. DON'T MIX IT UP WITH lingual branch of the sinus and body (pressoreceptors and mandibular branch of the 5th CN which is carrying ONLY chemoreceptors). general sensation from the anterior two-thirds of the tongue

Manifestation: ● Difficulty Of Swallowing and Absent Gag Reflex. Nerve ● Dysfunction Of The Parotid Gland (Dry Mouth). Lesion ● Impairment Of Taste And Sensation Over The Posterior One-third Of The Tongue ,Palate And Pharynx.

6 Glossopharyngeal (IX) 9th Cranial Nerve How to Test for 1x nerve Injury?

Have the patient open the mouth and inspect the palatal 1 arch on each side for asymmetry. Use a tongue blade to depress the base of the tongue gently if necessary. 2

Ask the patient to say "ahhh" as long as possible. Observe the palatal arches as they contract 3 and the soft palate as it swings up and back in order to close off the Normal palatal arches will nasopharynx from the constrict and elevate, and the oropharynx. uvula will remain in the midline as it is elevated. With paralysis there is no 4 elevation or constriction of the affected side. warn the patient that you are going to test the gag reflex. 5 Gently touch first one and then the other palatal arch with a tongue blade, waiting each time for gagging.

7 Vagus (X) Cranial Nerve ● It is a Mixed nerve. ● Its name means wandering (it goes all the way to the ), So it is the longest and most widely distributed cranial nerve. ● The principal role of the vagus is to provide parasympathetic supply to organs throughout the and upper abdomen. ● It also gives sensory and motor supply to the pharynx and larynx.

Superficial attachment Course

● its rootlets exit from the medulla 1. The vagus runs down the on the between olive and inferior cerebellar prevertebral muscles and fascia. peduncle. 2. The internal jugular vein lies behind it, ● Leaves the skull through jugular and the internal and common carotid foramen. It occupies the posterior arteries are in front of it, all the way aspect of the carotid sheath between down to the superior thoracic aperture. the internal jugular vein laterally and 3. It lies on the prevertebral muscles and the internal and common carotid fascia. arteries medially. 4. Enters thorax through its inlet:

● Right Vagus descends in front of the Right subclavian artery.

● Left Vagus descends between the left common carotid and Left subclavian arteries.

8 Vagus (X) & Communications : it has 2 ganglia

Superior ganglion in the jugular foramen with: ● Inferior ganglion of glossopharyngeal nerve 01 ● Superior cervical sympathetic ganglion ● Facial nerve.

Inferior ganglion just below the jugular foramen with:

● Cranial part of . ● . ● Superior cervical sympathetic ganglion. 02 ● 1st cervical nerve.

9 Vagus (X) Cranial Nerve

Component of fibers & Deep origin

Type of fibers Nuclei Structure innervated

GVE fibers: General synapses in , Visceral Efferent Dorsal Nucleus of short postganglionic fibers innervate Vagus Cardiac muscle, smooth muscles, respiratory, gastrointestinal systems. And glands of viscera.

SVE fibers: Special Muscles of: Visceral Efferent Pharynx (except stylopharyngeus) Nucleus Ambiguus Larynx Palate (except the tensor palati) Upper part of esophagus

GVA fibers: General carry impulse from viscera in neck, thoracic and Visceral Afferent Nucleus of solitary abdominal cavities Chemoreceptors in aortic bodies tract (NST). and baroreceptors in aortic arch. (was written in the summary)

SVA fibers: Special Spinal Tract Sensation from auricle, external acoustic meatus Visceral Afferent & nucleus of and cerebral dura mater,esophagus, tympanic membrane , external auditory meatus and part of trigeminal chonca of the middle ear (was written in the summary)

10 Vagus (X) Cranial Nerve Branches:

Meningeal : to the dura To carotid body

Pharyngeal :it enters the wall of the pharynx. It supplies the mucous membrane of the pharynx, superior Auricular nerve: to the external and middle constrictor muscles, and acoustic meatus and tympanic Branches all the muscles of the palate except membrane. the tensor palati.

Recurrent Laryngeal :(both) the recurrent laryngeal nerve goes round Superior Laryngeal: It divides into: the subclavian artery on the right, and (1) Internal Laryngeal :(sensory) It round the arch of the aorta on the left It provides sensation to the hypopharynx, runs upwards and medially alongside the epiglottis, and the part of the larynx the trachea, and passes behind the that lies above the vocal folds. (also carry lower pole of the thyroid gland. general and special sensation from the gives motor supply to all the muscles of root of the tongue) the larynx, except the cricothyroid. It (2) External Laryngeal :(motor)supplies also provides sensation to the larynx the cricothyroid muscle. below the vocal folds.

11 Vagus (X) Cranial Nerve Nerve lesion : Manifestation:

● Produce palatal and pharyngeal and laryngeal paralysis Nerve ● Abnormalities of esophageal motility, gastric acid secretion, Lesion gallbladder emptying, and heart rate; and other autonomic

dysfunction.

1. Lateral medullary syndrome: ● A degenerative disorder seen 1. Listen to the patient talk. over age of 50 mostly due to ◄ Thrombosis of the Inferior 2. Hoarseness, whispering, nasal Cerebellar Artery. speech, or the complaint of CAUSES OF IX & X NERVE aspiration or regurgitation of 2. Tumors compressing the cranial LESIONS liquids through the nose nerves in their exiting foramina should make you especially from the cranium via the skull mindful of abnormality base How to diagnose 10th nerve 3. Give the patient a glass of ● Manifested by: Injury? water to see if there is choking A. Ipsilateral paralysis of the or any complaints as it is muscles of the Palate, Pharynx swallowed. and Larynx. B. Ipsilateral loss of Taste from the 4. Laryngoscopy is necessary to Posterior Third of tongue. evaluate the vocal cord.

12 Practice Q1: Which one of the CN arise in groove between olive & inferior Q5: A patient was shown to have absent gag reflex. Which nerve is most likely affected: cerebellar peduncle: A. abducent IV A. facial B. glossopharyngeal IX B. vagus C. hypoglossal XII C. glossopharyngeal D. facial nerve VII D. hypoglossal Q2: 9 and 10 exit the cranial cavity through:. Q6: Which of the following nuclei give fibers to muscles of pharynx and larynx? A. foramen magnum A. nucleus solitarius. B. B. nucleus ambiguus. C. jugular foramen C. nucleus of trigeminal. D. carotid foramen Q7: Cricothyroid is supplied by which branch of the : Q3: The tympanic branch of glossopharyngeal supplies: A. internal laryngeal. A. parotid gland B. external laryngeal. B. C. recurrent laryngeal. C. pituitary gland D. not supplied by vagus nerve D. sublingual gland Q8 : Which of these is correct Q4: The right vagus nerve descends: A. Lingual branch of 9th CN carries only, general sensation from the posterior half of the tongue A. in front of right subclavian artery. B. Lingual branch of 9th CN carries only, special sensation from the posterior third of the tongue. B. in front of right subclavian vein C. Lingual branch of 5th CN carries general sensation from the anterior two-thirds of the tongue C. between left common carotid and subclavian arteries. D. Lingual branch of 9th CN carries, general & special sensation from the posterior half of the tongue D. between right common carotid and subclavian arteries.

Answers: Q1(B) Q2( C) Q3(A) Q4(A) Q5(C) Q6(B) Q7(B) Q8(C) 13 Members board

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