1. Cranial Nerves IX & X
Prof. Mujahid Khan

2. Objectives:
At the end of the lecture, the students should be able to:
Describe the component fibers of 9th & 10th cranial nerves
List the nuclei of the 9th & 10th nerves in the brain stem
Describe the course and relations of the 9th & 10th cranial nerves in the head & neck
List the branches of each of these 2 nerves
Describe how to test the integrity of these 2 nerves
Describe the effect of lesion of any of these 2 nerves

3. Names of Cranial Nerves
Ⅰ Olfactory nerve
Ⅱ Optic nerve
Ⅲ Oculomotor nerve
Ⅳ Trochlear nerve
Ⅴ Trigeminal nerve
Ⅵ Abducent nerve
Ⅶ Facial nerve
Ⅷ Vestibulocochlear nerve
Ⅸ Glossopharyngeal nerve
Ⅹ Vagus nerve
Ⅺ Accessory nerve
Ⅻ Hypoglossal nerve

4. Classification of Cranial Nerves
Sensory cranial nerves: are composed entirely of afferent (sensory) nerve fibers bringing sensations to the brain
Ⅰ Olfactory nerve
Ⅱ Optic nerve
Ⅷ Vestibulocochlear nerve
Motor cranial nerves: are composed entirely of efferent (motor) fibers
Ⅲ Oculomotor nerve
Ⅳ Trochlear nerve
Ⅵ Abducent nerve
Ⅺ Accessory nerve
Ⅻ Hypoglossal nerve
Mixed cranial nerves: possess both sensory and motor fibers
Ⅴ Trigeminal nerve
Ⅶ Facial nerve
Ⅸ Glossopharyngeal nerve
Ⅹ Vagus nerve

5. Cranial Nerves Anatomical origin There are 12 paired cranial nerves
The first 2 cranial nerves attach directly to forebrain (frontal lobe), while the rest attach to brain stem
1- Olfactory system is attached to forebrain
2- Optic nerve also is described in visual pathway
Cranial nerves have nuclei (cranial nerve nuclei) in the brain stem

6. Cranial Nerves
3 & 4- Occulomotor & trochlear nerves are attached to midbrain 5- Trigeminal nerve is attached to antero-lateral surface of pons & 8- Abducent, Facial & vestibulo-cochlear nerves are lying between pons & medulla oblongata from medial to lateral 9- Hypoglossal nerve is attached to antero-lateral sulcus of medulla oblongata 10, 11 & 12- Glossopharyngeal, vagus & accessory nerves are attached to postero-lateral sulcus of medulla oblongata

7. Cranial Nerves

9. Glossopharyngeal (IX)
General characteristics of CN IX ● mediates taste (gustation), salivation, and (with CN X and CN XII) swallowing ● mediates input from the carotid sinus, which contains baroreceptors that monitor arterial blood pressure ● mediates input from the carotid body, which contains chemoreceptors that monitor the carbon dioxide and oxygen concentration of the blood

10. Glossopharyngeal (IX)
General characteristics of CN IX ● the nerve of the third pharyngeal arch ● predominantly a sensory nerve ● exits the brainstem (medulla) from the post-olivary sulcus with CN X ● exits the skull via the jugular foramen with CN X and CN XI Branches: Lingual Carotid sinus branch Otic ganglion

12. Glossopharyngeal (IX)
1. ● innervates the middle ear cavity and part of the external auditory meatus ● has cell bodies in the superior glossopharyngeal ganglion ● projects its central processes to the spinal trigeminal tract and nucleus

13. Glossopharyngeal (IX)
2. ● innervates structures derived from endoderm (e.g., foregut) ● innervates the mucous membranes of the posterior third of the tongue, tonsil, upper pharynx (soft palate), tympanic cavity, and auditory tube ● innervates the carotid sinus (baroreceptors) and the carotid body (chemoreceptors) ● has cell bodies in the inferior (petrosal) ganglion ● the afferent limb of the gag reflex and the carotid sinus reflex 3. ● innervates the taste buds of the posterior third of the tongue

14. Glossopharyngeal (IX)
4. ● innervates the stylopharyngeus muscle ● arises from the nucleus ambiguus of the lateral medulla 5. ● a parasympathetic component that innervates the parotid gland ● consists of preganglionic neurons in the inferior salivatory nucleus of the medulla

15. GLOSSO-PHARYNGEAL NERVE (9TH CRANIAL NERVE )
inf. cerebellar peduncle 1
Nuclei:
-Nucleus ambiguus (A)
-Nucleus dorsalis (B)
-Nucleus solitarius (C)
-Inferior salivary nucleus (D)
the n. in groove between olive and inf. cerebellar peduncle
pons
medulla
olive
tongue 2 3 5
site of hyoglossus m. 7 8 9 4 6
glosso- pharyngeal n.
2 ganglia 1
Course of glosso-pharyngeal nerve (9th cranial nerve)

16. اسم ورقم المقرر – Course Name and No.
6/10/2019

18. BRANCHES OF GLOSSOPHARYNGEAL NERVE1 2 3 4 5 6
tongue
ganglia a b c d e f
glosso- pharyngeal n.
1.Tympanic nerve
2.  Nerve to stylopharyngeus
3.Pharyngeal branches
4.Carotid nerve
5.Terminal branches

19. Glossopharyngeal (IX)
Clinical correlations: lesions of CN IX 1. Loss of the gag (pharyngeal) reflex (interruption of afferent limb) 2. Loss of the carotid sinus reflex (interruption of the sinus nerve) 3. Loss of taste from the posterior third of the tongue 4. Glossopharyngeal neuralgia

20. Vagus (X)
General characteristics of CN X ● mediates phonation, swallowing (with CN IX and CN XII), elevation of the palate, and taste ● innervates viscera of the neck, thorax and abdomen ● the nerve of the fourth and sixth branchial arches ● exits the brainstem (medulla) from the post-olivary sulcus ● exits the skull via the jugular foramen with CN IX and CN XI

21. Left Vagus Nerve Course
Enter thoracic inlet between left common carotid and left subclavian arteries
Crosses the left side of the aortic arch where left recurrent laryngeal nerve branches off
Passes posterior to left lung root contributing to the pulmonary plexus
Descends on the anterior surface of the esophagus and forms anterior esophageal plexus
Forms anterior vagal trunk at esophageal hiatus where it leaves thorax and passes into abdominal cavity, then divides into anterior gastric and hepatic branches

22. Right Vagus Nerve Course
Travels downward anterior to the right subclavian artery and enter thoracic inlet on right side of trachea
Passes posterior to right lung root contributing to the pulmonary plexus
Then passes on to the posterior surface of esophagus and forms posterior esophageal plexus
Forms posterior vagal trunk at esophageal hiatus where it leaves thorax and passes into abdominal cavity, then divides into posterior gastric and celiac branches

23. Vagus Nerve (Ⅹ) Branches in neck
Superior laryngeal nerve: passes down side of pharynx and give rise to
Internal branch, which pierces thyrohyoid membrane to innervate mucous membrane of larynx above fissure of glottis
External branch, innervates cricothyroid
Cervical cardiac branches: descend to terminate in cardiac plexus
Others: auricular, pharyngeal and meningeal branches

24. Vagus Nerve (Ⅹ) Superior laryngeal nerve External branch
Internal branch
External branch

25. Vagus Nerve (Ⅹ) Branches in thorax Recurrent laryngeal nerves
Right one hooks around right subclavian artery, left one hooks aortic arch
Nerves enter larynx posterior to cricothyroid joint, the nerve is now called inferior laryngeal nerve
Innervations: laryngeal mucosa below fissure of glottis, all laryngeal muscles except cricothyroid
Bronchial and esophageal branches

26. Vagus (X)
1. ● innervates the infratentorial dura (with C2 and C3) external ear, external auditory meatus, and tympanic membrane ● has cell bodies in the superior (jugular) ganglion ● projects its central processes to the spinal trigeminal tract and nucleus 2. ● innervates the mucous membranes of the pharynx, larynx, esophagus, trachea, and thoracic and abdominal viscera (to the mid-transverse colon) ● has cell bodies in the inferior ganglion

27. Vagus (X)
3. ● innervates the taste buds over the epiglottis and soft palate ● has cell bodies in the inferior ganglion 4. ● innervates the pharyngeal arch muscles of the larynx and pharynx, striated muscle of the upper esophagus, musculus uvulae, and levator palati and palatoglossus ● arises from the nucleus ambiguus in the lateral medulla ● provides the efferent limb of the gag reflex

28. Vagus (X)
5. ● innervates the viscera of the neck and the thoracic and abdominal cavities as far as the mid-transverse colon ● consists of preganglionic parasympathetic neurons in the dorsal motor nucleus of the vagus, which project to the intramural ganglia of the viscera

29. Vagus (X)
Clinical correlations: lesions of CN X ● result in the following conditions: 1. Ipsilateral paralysis of the soft palate, pharynx, and larynx leading to dysphonia (hoarseness), dyspnea, dysarthria, and dysphagia 2. Loss of the gag (palatal) reflex 3. Anesthesia of the pharynx and larynx, leading to unilateral loss of the cough reflex 4. Aortic aneurysms and tumors of the neck and thorax ● frequently compress the vagus nerve

31. X : Vagus Nerve
It is mixed nerve, attached lateral to olive of medulla caudal to glossopharyngeal nerve in groove between olive & inferior cerebellar peduncle
It receives afferent fibers from:
1-Receptors for general sensation in pharynx, larynx, tympanic membrane, external acoustic meatus
2-Chemoreceptors in aortic bodies and baroreceptors in aortic arch
3-Receptors in thoracic & abdominal viscera

32. X: Vagus Nerve Fibers
1-Afferent fibers for general sensation: end in sensory nucleus of trigeminal and visceral sensory afferents end in nucleus solitarius
2-Efferent Motor fibers: arise from nucleus ambiguus of medulla to innervate muscles of soft palate, pharynx, larynx to control swallowing and speech
3-Efferent parasympathetic fibers: arise from dorsal nucleus of vagus to supply CVS, RS & GIT

33. VAGUS NERVE Nuclei : 4 nuclei in the medulla -Nucleus ambiguus (A)1 2 3 4 5
vagus
pharyngeal br.
sup. laryngeal
carotid br.
recurrent laryngeal
Nuclei : 4 nuclei in the medulla
-Nucleus ambiguus (A)
-Nucleus dorsalis (B)
-Nucleus solitarius (C)
-Spinal tract and nucleus of trigeminal nerve (D) A B C D
pyramid
olive
Inf. cerebellar peduncle
medulla
vagus n.
COURSE OF VAGUS n.

34. BRANCHES OF VAGUS NERVE1 3 4 5 8 7 6 S
vagus n.
1. Meningeal branch
2. Communicating branches
3. Auricular branch
4. Pharyngeal branch
5 .Superior laryngeal nerve which
divides into:
a. External laryngeal nerve (motor)
b. Internal laryngeal nerve (sensory)
6. Carotid branch
7. Cardiac branches
8. Right recurrent laryngeal nerve
R.L.N

35. THE END