CN 9,10,11,12 ANATOMY AND FUNCTION nerves .pptx
- 1. ANATOMY AND FUNCTION OF CN IX,X,XI,XII -:Under the guidance of:- Dr.Rajesh Jain Sir(Senior Professor & Unit Head) Dr.Pinki Tak Ma’am(Associate Professor) Dr.Monika Chaudhary Ma’am(Asst. Professor) • Presented By:- • Dr.Manish Kumar Sharma • MU-2
- 2. Classification of Cranial Nerves • .
- 3. GLOSSOPHARYNGEAL - IX th cranial nerve Mixed (containing both sensory and motor fibers) Origin of Nerve The nerve arises in 3-6 rootlets from medulla oblongata These rootlets emerges through postero-lateral sulcus of upper medulla, just above the rootlets of vagus nerve
- 4. Nuclei of Glossopharyngeal nerve Nerve has 4 nuclei 1.The motor nucleus-Nucleus ambiguus- associated with 9th, 10th and cranial part of the 11th nerve. 2.Inferior salivatory nucleus-The parasympathetic nucleus of gossopharyngeal nerve. 3.The sensory nuclei- (A).Spinal nucleus of trigeminal nerve-associated with cranial nerve 5,7,9 and 10 . (B).Nucleus of the tractus solitarius(NTS)-associated with cranial nerve 9 and 10.
- 5. Functional components, nuclei, and functions of glossopharyngeal nerve Functional components Nuclei Functions Special visceral efferent (SVE) Nucleus ambiguus To Supply stylopharyngeus muscle-helps in swallowing General visceral efferent (GVE) Inferior salivatory nucleus Provide parasympathetic fibers to parotid gland General visceral afferent (GVA) Nucleus tractus solitarius Receive general sensation from pharynx, palate, posterior one- third of tongue, tonsil, carotid body, and carotid sinus Special visceral afferent (SVA) Nucleus tractus solitarius Receive taste sensation from posterior one-third of tongue including circumvallate papillae General somatic afferent (GSA) Spinal Nucleus of trigeminal nerve General sensation from middle ear, eustachian tube,tympanic membrane.
- 6. Course and Relations Intracranial course • Rootlets of glossopharyngeal nerve pass forward and laterally towards the jugular foramen in posterior cranial fossa • Here, they unite to form single nerve trunk • Just after formation, leaves cranial cavity through anterior compartemet of jugular foramen, within separate sheath of dura mater
- 9. Branches of glossopharyngeal nerve and their functions Branch Functions Tympanic Carries sensation from mucous membrane of tympanic cavity, tympanic membrane, mastoid antrum, mastoid air cells and most of auditory tube. Preganglionic parasympathetic fibers of tympanic branch (fibers from inferior salivatory nucleus) supply parotid glands through otic ganglion. Carotid Receive afferent signals from carotid sinus(sense arterial blood pressure) and carotid body(sense chemical composition of bllod) . Pharyngeal Receive Sensation from mucosa of pharynx Muscular Stylopharyngeus Tonsillar Supply palatine tonsil, soft plate, and faucial pillars. Lingual General and taste sensation: From posterior one-third of tongue and circumvallate papillae Auricular Receive sensations from Pinna and External auditory meatus.
- 10. Right Cortex Left Cortex N UMN LMN SUPRANUCLER LESION Unilateral – No neurological deficit Bilateral- Pseudobulbar palsy NUCLEAR AND INTRAMEDULLARY LESION-cause glossopharyngeal neuralgia,absence of gag reflex ,loss of taste sensation from posterior2/3 etc. causes Include Syringobulbia, demyelinating disease, MND and Malignancy • INFRANUCLEAR and EXTRAMEDULLARY Lesions-Lesions within Retropharyngeal and Retroparotid space eg-Jugular foramen syndrome (Vernet syndrome) Collet-Sicard syndrome and Villaret syndrome Clinical Integration
- 11. (1).Gag reflex (A)afferent limb-CN IX (B) efferent limb-CN IX,X,V,XII How to elicit gag reflex-The reflex is elicited by touching the lateral oropharynx with a tongue blade, applicator stick, or similar object. Motor response-. There are five motor components: (1)elevation of the soft palate to seal off the nasopharynx, (2)closure of the glottis to protect the airway, and (3)constriction of the pharynx to prevent entry of the substance. (4)jaw opening (5)tongue thrusting Absent gag reflex- .Unilateral absence signifies a lower motor neuron lesion causes are-injury of cranial nerve ix,x or brain stem stroke and trauma. Gag reflex may found absent bilaterally in 37% of healthy individuals.other cause are bilateral injury of CN-9,10 or their nucleus(NTS,NA),brain stem death. Hyperactive gag reflex- may occur with bilateral cerebral lesions as in pseudobulbar palsy and amyotrophic lateral sclerosis.
- 12. 2.Glossopharyngeal neuralgia • In this type of neuralgia patient experiences attacks of severe lancinating pain originating in one side of the throat or tonsillar region and radiating to the eustachian tube, tympanic membrane, external auditory canal and behind the angle of the jaw. • Precipitated by swallowing, talking, eating or coughing. It can lead to syncope, convulsions, and rarely cardiac arrest because of stimulation of the carotid sinus reflex.
- 13. VAGUS NERVE • X th cranial nerve • Due to vague or extensive course, termed as vagus nerve. Longest and most widely distributed cranial nerve. Origin of Vagus Nerve: Arises by about 10 rootlets from lateral aspect of the medulla between olive and inferior cerebellar peduncle • These rootlets unite to form single nerve trunk
- 14. Functional components, nuclei and functions of vagus nerve Functional components Nuclei Functions Special visceral efferent (SVE) Nucleus ambiguus Supply to muscles of Palate, pharynx, and larynx. General visceral efferent (GVE) Dorsal nucleus of vagus Parasympathetic fibers for thoracic and abdominal viscera General visceral afferent (GVA) Nucleus tractus solitarius General sensation from pharynx, larynx, esophagus and from thoracic viscera and carotid body Special visceral afferent (SVA) Nucleus tractus solitarius Taste sensation from posterior most part of tongue and epiglottis General somatic afferent (GSA) Nucleus of spinal tract of trigeminal nerve General sensation from skin of external ear . GVA
- 15. Divided into following parts • Intracranial course • In neck • In thorax • In abdomen • Intracranial course • Nerve rootlets of vagus nerve join to form single nerve trunk runs laterally • Passes through intermediate compartment of jugular foramen in common sheath of dura mater with accessory nerve • Gets joined by accessory nerve in jugular foramen Course and Relations
- 16. In neck • After coming out of cranial cavity through jugular foramen,vagus nerve descends vertically within carotid sheath in between internal jugular vein and internal and common carotid arteries. Course and Relations In thorax- Here it gives cardiac,esophageal and pulmonary branches Both side nerve Passes downward along trachea up to root of lung .Right and left vagus give branches pass around right subclavian artery and arch of aorta respectively and then ascends upward to supply larynx as Right and Left recurrent laryngeal nerve. Further passes downward as Left vagus nerve along anterior surface of esophagus to form anterior vagal trunk and Right vagus nerve along posterior surface of esophagus to form posterior vagal trunk .Both side nerve exit thorax through esophageal opening of diaphragm.
- 18. Course and Relations In abdomen-Here it supply from stomach to midgut till splenic flexure. • After entering in the abdomen -Anterior vagal trunk divides into hepatic,pyloric and gastric branches and runs along lesser curvature of stomach. • Posterior vagal trunk passes posterior to esophagus and gives gastric and coeliac branches and nerve of Grassi.
- 19. Branches of vagus nerve Branch Functions Meningeal branches Sensory supply to dura mater of posterior cranial fossa Auricular branch (Arnold’s or alderman’s nerve) Sensory supply to the posterior half of external auditory meatus,tonsills,outer surface of the tympanic membranes and concha. Pharyngeal branches Supply all muscles of pharynx except stylopharyngeus which is supplied by glossopharyngeal nerve. supply all muscles of soft palate except tensor veli palatini which is supplied by mandibular nerve Carotid branches Sensation from carotid body and sinus Right recurrent laryngeal nerve Supply: All intrinsic muscles of larynx except cricothyroid which is supplied by external laryngeal nerve Mucous membranes of larynx below the vocal folds
- 20. Branches of vagus nerve Branch Functions Superior laryngeal branch Internal laryngeal nerve: Sensation from pharynx, epiglottis, vallecula and mucosa of larynx up to vocal folds External laryngeal nerve: Supplies cricothyroid and inferior constrictor of pharynx Cardiac branches Communicates with cardiac branches of the sympathetic nervous system to form the cardiac plexus. Pulmonary branches Arise in the thorax; communicate with filaments from the sympathetic division to form the pulmonary plexuses. Esophageal branches Arise in the thorax; join splanchnic nerves and thoracic sympathetic nerves to form esophageal plexus. Gastrointestinal branches Arise in the abdomen; form gastric, celiac, and hepatic plexuses .
- 21. Right Cortex Left Cortex N UMN LMN SUPRANUCLER LESION Unilateral – No deficit Bilateral- Pseudobulbar palsy NUCLEAR &INFRANUCLEAR LESION- result in ipsilateral palatal, pharyngeal and laryngeal paralysis and usually associated with affection of other CN nuclei and roots eg- ALS, syringobulbia, and neoplasms ,aneurysm,tauma to skullbase,sarcoidoss. • Extrapyramidal Lesion -produce difficulty with swallowing and talking Eg-parkinson disease- Clinical Integration
- 22. Nerve injury Effect of Weakness Cricothyroid palsy(due to external superior L.N injury) Loss of tension and elongation of the vocal cord in phonation; loss of high tones,horseness of voice and inspiration with stridor Total unilateral palsy(due to unilateral RLN injury) Eg-MS,Bronchogenic carcinoma,Aortic aneurysm Both adduction and abduction affected; involved cord lies in cadaveric position, motionless in midabduction; voice low-pitched and hoarse little or no dyspnea due to opposite side working cord. Total bilateral palsy(due to bilateral RLN injury)Eg- GBS, Thyroidectomy,Lymphom a Both cords in cadaveric position; phonation and coughing lost; marked dyspnea with stridor. Clinical Integration-vocal fold palsy
- 23. . Clinical testing of vagus nerve • For clinical testing of vagus nerve, ask patients to open mouth and observe soft palate. • Palatal arches are equal on both sides and uvula is centrally placed. • In case of 10th nerve paralysis, there is no arching of palate on paralysed side and uvula is deviated to normal side. • Lesion of vagus nerve produce- Nasal regurgitation of swallowing liquids,nasal twang in voice,hoarseness of voice,flattering of the palatal arches,dysphagia,loss of cough reflex. •Cadaveric position of the palatal arch,Cadaveric position of vocal cord in bilateral lesion
- 24. Clinical Integration Aldermen’s nerve phenomenon: • Stimulation of auricular area supplied by vagus cause increased appetite • In Alderman, in ancient Rome, used to stimulate appetite by dropping cold water behind ear. This stimulation causes reflex, increased gastric motility and acid secretion. • Irritation of auricular branch of vagus nerve by wax or syringing of external ear, reflexly causes cough, vomiting, giddiness or sudden cardiac arrest. • Vagotomy: • Surgical resection of vagus nerve to reduce acid secretion of stomach for treatment of peptic ulcers • Three types: of vagotomy-(1)Truncal (2)Selective (3)Highly selective vagotomy Advantages: Preserve innervations of pylorus and prevents post-vagotomy retention syndrome
- 25. Vagally Mediated Reflexes Oculocardiac reflex- is bradycardia caused by pressure on the eyeball. It may also be induced by painful stimulation of the skin on the side of the neck. • The afferent limb is carried by cranial nerve (CN) V and the efferent by CN X. . Usually, the pulse is not slowed more than 5 to 8 beats per minute. • The oculocardiac reflex may be absent in lesions involving CN X. It is sometimes used to slow an excessively rapid heart rate, as in tachyarrhythmias. • Vomiting reflex-produces reverse peristalsis in the esophagus and stomach, with forceful ejection of material from the stomach reflex is mediated by dorsal efferent nucleus. • Swallowing reflex -is caused by stimulation of the pharyngeal wall or back of the tongue. Afferent impulses travel through CNs V, IX, and X and efferent impulses through CNs IX, X, and XII. • Carotid sinus reflex- is produced by stimulation of the carotid sinus or the carotid body by pressure at the carotid bifurcation. It causes slowing of the heart rate, fall in blood pressure, decrease in cardiac output, and peripheral vasodilatation. When the response is exaggerated, there may be syncope. The afferent limb of the reflex is carried over CN IX and the efferent over CN X.
- 26. ACCESSORY NERVE-XI th Cranial nerve • Origin of Nerve: in two parts Cranial root • Emerges as 4–5 rootlets from posterolateral sulcus of medulla • They unite to form a single trunk and joins vagus nerve to form vagoaccessory complex • Spinal root • Arises as row of filaments from upper 5 (c1-c5) segments of spinal cord between ventral and dorsal nerve roots • In vertebral canal, filaments unite to form single trunk which ascend in front of dorsal root and pass through foramen magnum.
- 27. Functional components, nuclei, and functions of spinal accessory nerve Functional components Nuclei Functions Special visceral efferent (SVE) Nucleus ambiguus Motor supply to muscles of Palate, pharynx, and larynx General somatic efferent (GSE) Spinal nucleus of accessory nerve Sternocleidomastoid and trapezius
- 28. Intracranial course • Cranial root – Runs laterally, to reach jugular foramen – In jugular foramen, cranial root unites for short distance now fuse with vagus nerve and further distributed through vagus. • Spinal root – Enters cranial cavity through foramen magnum. In cranial cavity, runs upward and laterally toward jugular foramen Here, joins with cranial root Leaves skull through intermediate compartment of jugular foramen . Course and Relations
- 29. Extracranial course of spinal part - Nerve descends vertically downward and backward around internal jugular vein and pierces deep surface of sternocleidomastoid muscle and anastomoses with fibers from C2 and C3 Emerges from sternocleidomastoid and runs backward and downward Passes deep to anterior border of trapezius at about 3.5 cm above clavicle and forms plexus with C3 and C4 nerve fiber deep to trapezius Course and Relations
- 30. Branches of spinal accessory nerve Spinal root: Supplies • Sternocleidomastoid along with C2 and C3 spinal nerves • Trapezius along with C3 and C4 spinal nerves • Cranial root (distributes through vagus nerve) • Pharyngeal branches to supply all muscles of soft palate except tensor veli palatini (supplied by mandibular nerve) and all the muscles of pharynx except stylopharyngeus (supplied by glossopharyngeal nerve) • Recurrent laryngeal nerve to supply all intrinsic muscles of larynx expect cricothyroid (supplied by external laryngeal nerve)
- 31. Clinical Integration Injury to spinal accessory(mostly iatrogenic) nerve.Results in • Paralysis of sternocleidomastoid muscle –Ask patient to turn chin to opposite side against resistance incase of injury there is inability to turn chin to opposite side • Paralysis of trapezius muscles –causes drooping of shoulder upper part of scapula move laterally and lower part move medially. • Torticollis (wry neck): Irritation of accessory nerve during biopsy of cervical lymph nodes may cause torticollis (spasmodic contraction of sternocleidomastoid muscle)
- 32. HYPOGLOSSAL NERVE • 12th cranial nerve • Purely motor and supplies all muscles of tongue except palatoglossus which is supplied by cranial part of accessory nerve. • Origin of Hypoglossal Nerve • Arises by rootlets on ventral aspect of medulla from anterolateral sulcus between pyramid and olive • Nucleus of nerve is about 2 cm long • Located in medulla, in floor of 4th ventricle, deep to hypoglossal triangle
- 33. Functional components, nuclei, and functions of hypoglossal nerve Functional components Nuclei Functions Special visceral efferent (SVE) Hypoglossal nucleus All intrinsic and extrinsic muscles of tongue except palatoglossus
- 34. Intracranial course • Rootlets of hypoglossal nerve run laterally behind vertebral artery and join to form two roots or bundles. Two roots unite in hypoglossal canal before they leave skull. Extracranial course • Exits skull through hypoglossal canal • Here, lies deep to internal jugular vein and internal carotid artery. • Then nerve descends between internal jugular vein and internal carotid artery at lower border of posterior belly of digastric, turns forward and crosses internal and external carotid arteries laterally. • Further runs forward and crosses the loop of lingual artery, hyoglossus, and genioglossus. • Finally, nerve enters tongue and divides into terminal branches Course and Relations
- 36. Branches (1) Branches of hypoglossal nerve proper Give branches to supply all intrinsic and extrinsic muscles of tongue except palatoglossus which is supplied by vagus nerve. (2) Branches of hypoglossal nerve containing C1 fibers These fibers give following branches Meningeal branches: • They enter cranial cavity through hypoglossal canal and supply dura mater of posterior cranial fossa • Descends hypoglossi or upper root of ansa cervicalis • Arises from hypoglossal nerve joins to inferior root of ansa cervicalis at level of cricoid cartilage Nerve to thyrohyoid: Crosses greater cornua of hyoid bone and supplied thyrohyoid muscle • Nerve to geniohyoid: Arises above hyoid bone and supply geniohyoid muscle
- 37. Clinical Integration There are 2 types of lesion of nerve (1)supranuclear lesion : • Occurs due to damage to corticobulbar fibers connecting motor area of cerebrum to hypoglossal nucleus • Results in upper motor neuron type of paralysis of tongue. • On protrusion, tongue deviates to opposite side of lesion,presence of speech difficulty and absence of atrophy and fibrillation found. • eg-stroke involving internal capsule and corona radiata. (2)Nuclear and Infranuclear lesions • - Results in atrophy,furrowing,fibrillations and ipsilateral deviation of tongue. • eg-Intramedullary - medial medullary syndrome, poliomyelitis and ALS. • Extramedullary -nasopharyngeal carcinoma,skull base injury,compression by vertebral artery and epidural abscess of nasopharyngeal space.
- 39. References • DeJong’s Neurologic Examination; 7th edition • Bickerstaff’s Neurological Examination in Clinical Practice 6th edition • Grays anatomy
- 40. Thank you
Editor's Notes
- #2: CN 1,2 ARISE FROM CEREBRUM 3,4 ARISE FROM MID BRAIN 5,6,7,8 ARISES FROM PONS CN9,10,11,12 ARISES FROM MEDULLA
- #3: ARISES BETWEEN INFERIOR CEREBELLAR PEDUNCLE AND OLIVE
- #4: IN THIS DIAGRAM ANTERIOR MOST PART IS PYRAMID WHICH ARE MOTOR TRACTS POSTERIOR TO IT ARE INFERIOR OLIVARY NUCLEUS POSTERIOR TO IT ARE NUCLEUS AMBIGUUS ,INF.SALIVATORY NU, AND SPINAL NU OF TRIGEMINAL ARRANGED IN ANTERIOR TO POSTERIOR MANNER .
- #8: Passes downward and forward between internal jugular vein and internal carotid artery Then passes between external and internal carotid arteries deep to styloid apparatus. Winds forward around the lower border and superficial surface of stylopharyngeus muscle. Finally, enters pharynx through gap between superior and middle constrictor of pharynx and divides into terminal branches
- #22: Thyroarytenoid Glottis has an oval instead of linear appearance on phonation;Bilateral abductors Both cords close to the midline and cannot be abducted; voice hoarse, severe dyspnea with inspiratory stridor Unilateral adductors Paralysis of one lateral cricoarytenoid; hoarseness and impairment of coughing Bilateral adductors Cords not adducted on phonation and voice either lost or reduced to whisper; inspiration normal without stridor or dyspnea voice hoarse; no dyspnea or stridor Arytenoid the larynx shows a small triangular slit posteriorly during phonation; inspiration is normal Unilateral abductors The cord lies close to midline; cannot be abducted on inspiration; voice hoarse; dyspnea uncommon because normal cord abducts on inspiration.
- #31: Other intracranial, extra medullary neoplasms -meningioma's and neurofibromas, which may extend through jugular foramen in dumbbell fashion. Basal skull fractures, meningitis, or processes at/just distal to the skull base give rise to a number of syndromes reflecting involvement of the lower CNs affecting both the SCM and the trapezius.