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Tim McDowell October 13, 2010

Brainstem II

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Brainstem II. Tim McDowell October 13, 2010. Objectives. Overview the anatomy and function of CNs VII Facial VIII Vestibulococholar IX Glossopharyngeal X Vagus XI Spinal Accessory XII Hypoglossal nerve Clinical cases and syndromes involving these nerves. Facial Nerve Anatomy. - PowerPoint PPT Presentation

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Page 1: Brainstem II

Tim McDowellOctober 13, 2010

Page 2: Brainstem II

ObjectivesOverview the anatomy and function of CNs

VII FacialVIII VestibulococholarIX GlossopharyngealX VagusXI Spinal AccessoryXII Hypoglossal nerve

Clinical cases and syndromes involving these nerves

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Facial Nerve Anatomy

Page 4: Brainstem II

Course of Peripheral Nerve:Exits ventrolateral pons (CPA) internal auditory meatus facial canal in petrous bone geniculate ganglion stylomastoid foramenparotid gland

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Facial Nerve FunctionMotor, parasympathetic, sensory functionsMotor:

Originate in motor facial nucleus (caudal pontine tegmentum)

Brachial motor branches control muscles of facial expression Temporal, zygomatic, buccal, mandibular, and cervical Branch off after parotid gland

Innervates stapedius muscle Branches shortly after geniculate ganglion in mastoid

segment

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Facial Nerve FunctionSensory:

Taste for anterior 2/3 of tounge chorda tympanageniculate ganglion

Sensation of portion of external auditory meatus, lateral pinnea and mastoid greater superfical petrosal nerve geniculate

ganglionTravel as Nervus Intermedius of Wrisberg,

receives fibers from geniculate ganglion then travels to rostal nucleus solitarius (taste), and nucleus of the spinal tract of CN V (exteroceptive)

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Facial Nerve FunctionParasympathetic

Originate in superior salivatory and lacrmial nucleus (pontine tegmentum)

Travel along nervus intermedius to: Sphenopalatine ganglion (lacrimal glands, nasal

glands) Submandibular ganglion (sublingual gland,

submandibular gland)

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QuizWhich of the following can cause a facial

nerve palsyA Mobius syndromeB Millard-Gubler SyndromeC 8 ½ syndromeD Melkersson-Rosenthal syndromeE All of the above

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Vestibulococholar NerveSpecial sensory

function which carries hearing and vestibular sense

Exits brainstem at cerebellopontine angle internal auditory meatus auditroy canal cochlea + vestibular organs

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Vestibulococholar Nerve Anatomy: AuditoryNeuroepithelial hair cells stimulated by

endolymph causing movement of basilar membrane Cell body spinal ganglion of the cochlear nerve cochlear nuclei (dorsal and ventral) in the lateral medulla

Tonotopic pattern:Low frequencies (apex of cochlea ventral

nuclei)High frequencies (basal hair cells dorsal

nucleus)

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Auditory PathwaysDorsal cochlear

nucleus dorsal acoustic striae (decussication) lateral lemniscus inferior colliculus

Ventral cochlear nuclei ventral acoustic striae (trapezoid body)superior olivary nucleus lateral lemniscus IC

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Auditory PathwaysCommissural

connections between superior olivary complexes, cochlear nuclei, nucleir of lateral lemniscus, and inferior colliculusTherefore unilateral

hearing loss is not seen in CNS lesions proximal to the cochlear nuclei

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Auditory Pathways3rd order neurons project from inferior

colliculus to medial geniculate body (thalamus) High-freq medialLow-freq apical-lateral

Auditory radiation white matter tract below putamen temporal lobe (primary auditory cortex- Brodmann’s area 41> audiotry association cortex area 42)High-freq medial, low-freq lateral

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Vestibulococholar Nerve Anatomy: VestibularMeasures angular and linear acceleration of the

head within the membranous labyrinth3 Semicircular canals (angular, measured by cristae

inside the ampulla): horizontal, anterior/superior, posterior/inferior

Utricle and saccule (linear, measured by maculae which contain otolith crystals)

Afferent connection to cell bodies of vestibular ganglion of Scarpa (inside internal acoustic meatus)Superior portion: anterior and horizontal semicircular

canals + utricleInferior portion posterior semicircular canal + saccule

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Vestibular PathwaysVestibular nerve projects to vestibular nuclei in

pontomedullary junctionSuperior (of Bechterew)Lateral (of Deiters)Medial (of Schwalbe)Inferior (descending nucleus of Roller)

Semicircular canals superior and medial nucleiMacular fibers medial and inferior vestibular nucleiVestibular nerve also projects inferior cerebellar

peduncle vestibulocerebellum (flocculonodualr lobes)

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Vestibular PathwaysOutput primarily re: feedback integration with

cerebellum, spinal cord, and brainstemMain connectinos:

Medial Longitudinal Fasciculus (conjugate eye mvmts) Superior vestibular n.ipsilateral All others contralateral

Medial Vestibulospinal Tract (descending MLF) Mostly medial vestibular nucleus cervical and upper

thorasic contralateral spinal cordLateral Vestibulospinal Tract (facilitates extensor

trunk tone + antigravity muscles) Lateral + inferior vestibular nuclei ipsilateral spinal cord

Cerebellum Ipsilateral flocculondular lobe + reciprocal connection

back thru juxtarestiform body

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Page 22: Brainstem II

Weber test: vibration at vertex, localizes to conductive hearing deficit and away from sensorineural hearing deficit

Rinne Test: air/bone cunduction compared in each ear

Dix-Hallpike:

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Quiz:What makes a Dix-Hallpike Positive in BPPV?

LatencyTorsional, upper pole beats towards groundFatigabilityReboundHabituation

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Glossopharyngeal Nerve AnatomyEmerges from

posterior lateral sulcus of medulla Jugular foramen widens to superior and petrous ganglia descends on lateral side of pharynx around stylopharyngeus muscle (+innervates) base of tougne

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Glossopharyngeal Nerve FunctionMotor:

stylopharyngeal muscle Mildly lower palatal arch Mild dysphagia

Supplied from nucleus ambiguusSensory:

taste +sensation to post. 1/3 of tougne sensation to soft palate, tonsils, pharyngeal wall,

tragus of ear, eustachian tube, mastoid regionChemoreceptive and baroreceptive afferents

from caroitid body + sinus

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Glossopharyngeal Nerve FunctionSensory Function continued

For taste + chemo/baro receptors, cell bodies in petrous ganglion, project to solitary nucleus (rostal: taste, caudal: chemo/baro receptors)

Exteroreceptive afferents, cell bodies in both petrous and superior ganglia spinal nucleus of V

Parasympathetic:Inferior salivatory nucleus otic ganglion

(synapse here) (Via V3) parotid gland

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Vagus NervePosterior sulcus of lateral medulla, multiple

rootlets trunk, exits via jugular foramen Two vagal ganglia here: jugular (sup) + nodose

(inf)Auricular ramus branches off concha of external

earMeningeal ramusdura matter of post fossaPharyngeal ramus pharyngeal plexus (with IX)Superior laryngeal nerve (arises near nodose

gangion): sensory to larynx + cricothyroid muscle

Page 28: Brainstem II

Vagus NerveIn neck travels with internal carotid art +

IJV)Cardiac rami: cardiac plexusRecurrent laryngeal nerves (left longer): all

muscles of larynx except cricothyroidThorax: give off pulmonary and esphogeal

plexusAbdomen: innervate abdominal viscera

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Vagus NerveMotor fibers originate from

doral motor nucleus of vagus: preganglionic parasympathetics

nucleus ambiguus: striated musclesSensory fibers:

Taste from epiglottis, hard & soft pallates, and pharynx, + general visceral afferents from oropharnyx, larynx, thorax and abdo viscera solitary nucleus (cell bodies in nodose ganglia)

Exteroreceptive sensation from ear spinal nucleus of V (cell bodies in juglar ganglion)

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Spinal Accessory NervePure motor nerveCranial root (becomes recurrent laryngeal nerve,

mostly travels with X)Spinal root: dorsolateral portion of ventral horn

in cervical spinal cord (rostal portion SCM, caudaltrapezius)

Exit cord between ventral and dorsal nerve rootlets, just dorsal to dentate ligament

Ascend together into skull through foramen magnum exits via jugular foramen neck to supply SCM and trapezius

NB: UMN innervation of SCM is ipsilateral

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Hypoglossal NerveMotor control of the tougneArises from hypoglossal nucleusExits medulla as multiple rootlets between

pyramid and inferior olivary nucleus hypoglossal foramen

NB UMN fibers cross before innervating hypoglossal nuclei

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Quiz:True or falseGlossopharyngeal neuralgia is commonly

associated with MS?FALSE

The most common cause of isolated CN XI is iatrogenic?TRUE

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Quiz:Clinical picture of:

Ipsilateral trapezius and sternocleidomastoid paresis and atrophy

Dysphonia, dysphagia, depressed gag reflex, and palatal droop on the affected side associated with homolateral vocal cord paralysis, loss of taste on the posterior third of the tongue on the involved side, and anesthesia of the ipsilateral posterior third of the tongue, soft palate, uvula, pharynx, and larynx

Often dull, unilateral aching pain localized behind the ear

Name the lesion. Where is it? Common causes?

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Vernet’s Syndrome (Jugular Foramen Syndrome)Lesion at jugular foramenCommon with glomus jugulare tumors and

basal skull fractures

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QuizClincial picture of isolated VI and XII paresis:

Godfresdsen syndromeClival tumor, often nasopharyngeal, poor

prognosis

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Other syndromes involving lower CN’s

Syndrome (Eponym) Nerves Affected Location of LesionCollet-Sicard Cranial nerves IX, X, XI, XII Retroparotid space usually;

lesion may be intracranial or extracranial

Villaret's Cranial nerves IX, X, XI, XII plus sympathetic chain; VII occasionally involved

Retroparotid or retropharyngeal space

Schmidt's Cranial nerves X and XI Usually intracranial before nerve fibers leave skull; occasionally inferior margin of jugular foramen

Jackson's Cranial nerves X, XI, and XII May be intraparenchymal (medulla); usually intracranial before nerve fibers leave skull

Tapia's Cranial nerves X and XII (cranial nerve XI and the sympathetic chain occasionally involved)

Usually high in neck

Garcin's (hemibase syndrome) All cranial nerves on one side (often incomplete)

Often infiltrative; arising from base of skull (especially nasopharyngeal carcinoma)

TABLE 13-1 Syndromes Involving Cranial Nerves IX through XII