Presentation on theme: "Chapter 15: Cranial Nerves"— Presentation transcript:
1Chapter 15: Cranial Nerves Chris RordenUniversity of South CarolinaNorman J. Arnold School of Public HealthDepartment of Communication Sciences and Disorders
2Functional Classification of CN Spinal Nerve classificationGeneral Efferent or Afferent: serve general motor, sensory.Cranial Nerves classificationReceptor type:General - just like spinal nervesSpecial –Use special receptors and neurons to serve additional specialized functionsSignal typeEfferent – MotoricAfferent SensoryVoluntary or reflexive?Somatic. Innervate somatic muscles (muscles that arise from the soma in the embryological stage – voluntary muscle control)Visceral. Innervate visceral structures.
37 Functional TypesGeneral Somatic Efferent (GSE) Activates Muscles from Somites (Skeletal, Extraocular, Glossal)General Visceral Efferent (GVE) Activates Visceral OrgansSpecial Visceral Efferent (SVE) Activates Muscles of face, palate, mouth, pharynx and larynx Excludes eye and tongue musclesSpecial Visceral Afferent (SVA) Mediates visceral sensation of taste from tongue Olfaction from NoseGeneral Visceral Afferent (GVA) Mediates sensory innervation from visceral organsGeneral Somatic Afferent (GSA) Mediates information from muscles, skin, ligament and jointsSpecial Somatic Afferent (SSA) Mediates special sensations of vision from retina and audition and equilibrium from inner ear
4Peripheral Nervous System (PNS) 12 pairs of cranial nerves-Sensory, motor, or mixed“On Old Olympus Towering Top A Famous Vocal German Viewed Some Hops.”“On Old Olympus Towering Top A Finn And German Viewed Some Hops.”
5Cranial Nerves (12 pair) Olfactory: smell Optic: vision Oculomotor: eyelid and eyeball movementTrochlear: motor for vision (turns eye downward and laterally)Trigeminal: chewing, face and mouth touch and painAbducens: motor to lateral eye musclesFacial: controls most facial expressions , taste, secretion of tears & salivaVestibulocochlear: sensory for hearing and balance (aka Acoustic, Auditory)Glossopharyngeal: sensory to tongue, pharynx, and soft palate; motor to muscles of the the pharynx and stylopharyngeusVagus Nerve: sensory to ear, pharynx, larynx, and viscera; motor to pharynx, larynx, tongue, and smooth muscles of the viscera, 2 parts: superior laryngeal branch and recurrent laryngeal branchSpinal Accessory Nerve: motor to pharynx, larynx, soft palate and neckHypoglossal Nerve: motor to strap muscles of the neck, intrinsic and extrinsic muscles of the tongueThere are 12 pair but only 7 pair relate to speech and hearing (5, 7-12)
6Special Sensory : smell I: OlfactorySpecial Sensory : smell-Injured by shearing (car accident) – unilateral loss of smellrad.usuhs.mil/cranial_nerves/timrad.html
7II: OpticSpecial Sensory: SightOptic nerve nuclei are located in the lateral geniculate bodyPupil constricts for light to contralateral eye, but not ipsilateral. Unilateral vision loss
8III: OculomotorSomatic Motor: Superior, Medial, Inferior Rectus, Inferior ObliqueVisceral Motor: Sphincter PupillaePupil asymmetry, no pupil reflex – regardless of which eye observes light. Difficulty with eye movements.
9IV: Trochlear(Latin for pulley)Somatic Motor: Superior ObliqueInjury leads to diplopia (due to eye drifting upward), esp when looking down
10V: TrigeminalSomatic Sensory: FaceSomatic Motor: Mastication (chewing), Tensor Tympani (reduced ossicle movement), Tensor Palati (soft palate – chewing and eustachion tubes)light touch and pain on the forehead (V1), cheeks (V2) and chin (V3).
11VI: AbducensSomatic Motor: Lateral RectusDamage to the nerve is seen with decreased ability to abduct the eye. (diplopia: affected eye is pulled medially)
12VII: Facial Somatic sensory: Posterior External Ear Canal Special Sensory: Taste (Anterior 2/3 Tongue)Somatic Motor: Muscles Of Facial ExpressionVisceral Motor: Salivary Glands, Lacrimal GlandsDrooping corner of mouth while at rest. Asymmetry of expressions (wrinkle forehead, raise eyebrows, etc)
13VIII: Vestibulocochlear Special Sensory: Auditory/BalanceCan patient hear finger rubbing near ear.
15X: Vagus Somatic Sensory: External Ear Visceral Sensory: Aortic Arch/BodySpecial sensory: Taste Over EpiglottisSomatic Motor: Soft Palate, Pharynx, Larynx (Vocalization and Swallowing)Visceral Motor: Bronchoconstriction, Peristalsis, Bradycardia, VomittingAsymmetric palate while saying ‘Aaah’, poor gag reflex (sensory = IX, motor = X)
16XI: Spinal AccessorySomatic Motor: Trapezius, SternocleidomastoidDrooping shoulder. Weakness turning head in one direction, difficult to shrug shoulders against resistance.
17XII: HypoglossalSomatic Motor: TongueObserve tongue while on floor of mouth. Twitching can suggest XII injury.
18Branchial Origin of Speech-Related Muscles Speech related muscles = visceral?Six branchial arches present in embryo One disappears during developmentSome cranial nerves originate from 5 brachial arches and are special visceral efferent nervesSpeech related nerves IncludeTrigeminal (V)Facial (VII)Glossopharyngeal (IX)Superior laryngeal and recurrent laryngeal branches of Vagus (X)
19Cranial Nerve Nuclei Midbrain (3)- Control Eye Muscles Pons (6) Two Motor N. of OculomotorOne Motor N. of TrochlearPons (6)Three Sensory N. of TrigeminalMesencephalic N.Primary Sensory N.Spinal Trigeminal N.Motor N. of Trigeminal N.Abducens N.Facial Motor N.
20Cranial Nerve Nuclei: Medulla (9) Cochlear N. (Hearing)Vestibular N. (Equilibrium)Salivary N. (Secretions)Dorsal Motor N. of Vagus (Visceral Motor)Hypoglossal N. (Tongue)Nucleus Solitarius (Visceral Sensory) afferent swallowingSpinal Trigeminal N. (Sensory)Nucleus Ambiguus (Laryngeal & Pharyngeal Motor) efferent swallowingInferior Olivary N. (Info to Cerebellum)
21Pathways - Corticobulbar Motor Corticobulbar tractFibers between cortex and brain stemCross midline at different levelsUpper and Lower Motor NeuronsClinical Signs:Lower Motor NeuronParalysisAbsent ReflexesFlaccid Muscle ToneFibrillationFasciculations (twitching)AtrophyUpper Motor NeuronSpasticityIncreased Tendon ReflexesContralateral Paresis
223 Major types of sensory pathways Pathways - Sensory3 Major types of sensory pathways1st order - Outside brainstem2nd order Cell bodies in gray matter of brainstem3rd order - Cell bodies in ventral posterior medial N. of Thalamus projecting to cortex in parietal lobeSmell, hearing and vision are exceptions to rule three
24Olfactory Nerve (I)Fibers pass through the foramina in the cribriform plate to olfactory bulb, olfactory tract to temporal cortex (uncus, amygdaloid N. and parahippocampal gyrus). Connects to limbic system and emotional brain.Olfactory ability decreases with ageAnosmia: impaired smell (ask patient to identify odors)
25Optic Nerve (II) Special somatic afferent Retina to Optic Nerve to Optic ChiasmTo Lateral Geniculate BodyTo Optic RadiationsTo Visual Cortex in Occipital LobeClinically:Injury results in visual field lossCommon visual field losses in Chapter 8 (ask client to closes one eye and fix gaze straight ahead. Determine when patient can see objects in parts of visual field)
26Oculomotor Nerve (III) General somatic efferentInnervate extrinsic muscles of eyeGeneral visceral efferentProvides parasympathetic projections to constrictor fibers of iris and ciliary musclesProvides motor innervation for iris to adjust to light and lens to focusEdinger-Westphal Nucleus
30Clinical Info: Oculomotor Nerve (III) Ptosis - eyelid droopOphthalmoplegiaproblems in adjusting to lightdeviation of eye movementsdiplopia (double vision)
31Trochlear IV General somatic efferent Only CN to exit brainstem dorsallyOnly CN that exits contralaterallyAnterior oblique muscle for eye movement is only functionClinicalDifficulty looking downward and outward when Trochlear is injuredeye drifts upward relative to the normal eye
33Superior Oblique Muscle Function Right Superior Oblique MuscleEye ball directed down and out
34Trigeminal (V) General somatic afferent Principal sensory nerve for head, face, orbit and oral cavitymediate sensations of pain, temperature, proprioception and fine discriminative touchSensations from anterior 2/3 of tongueThree sensory branchesOphthalmicMaxillaryMandibular
36Trigeminal (V) Special visceral efferent Motor for mastication muscles for chewing and speakingInternal and external pterygoidTemporalisMasseterMylohyoidAnterior belly of digastricTensor veli palatiniTensor tympaniReflex for jaw jerk reflex (mandibular)
39Clinical Info: Trigeminal (V) SensoryTest for touch discrimination in different facial zonesCheck for sneeze and corneal reflexesTic of douloureux (trigeminal neuralgia) which is excruciating painMotorCheck for paralysis or paresis of ipsilateral muscles of masticationCheck for absent or exaggerated jaw reflexLook for deviation of jaw toward side of injuryUnilateral lesion has mild effect on bite strength while bilateral has severe effect
40Abducens (VI) General somatic efferent Innervates only a single muscle: lateral rectus muscle which moves eye laterallyClinical Info:When injured, medial rectus muscle is unopposed – eye shifts mediallySusceptible to disruptionCheck for medial strabismusTurns in mediallyDouble visionLeft Abducens (VI) Nerve ParalysisLeft eye is deviated medially
41Left Abducens (VI) Nerve Paralysis Diplopia Disappears on Eye Movement to the Right
43General visceral efferent Facial Nerve (VII)General visceral efferentParasympathetic innervation of lacrimal gland and palatal salivaInnervation of mucous membrane secretions in mouth and pharynxSpecial visceral afferentGustatory sensations from anterior 2/3 of tongue
44Facial Nerve (VII) Special visceral efferent Primary motor nerve for facial musclesExtrinsic Muscles of earCats can rotate outer earStapedius MuscleContraction attenuates soundSwallowingStylohyoid MusclePosterior Belly of Digastric MuscleLacrimal secretion - Tears
45Clinical Info: Facial Nerve (VII) Upper Motor Neuron DiseaseWhy is it hard to only raise one eyebrow?Unilateral paresis of muscles of lower half of faceMuscles above bilaterally innervatedBilateral lesion can cause paralysis of upper and lower muscles bilaterallyLower Motor Neuron DiseaseInjury near pons can cause lower motor neuron diseaseUnilateral Paralysis of all facial muscles, stapedial muscle and taste in 2/3 of tongue
48Clinical Info: Facial Nerve (VII) Bell’s PalsyLMN syndrome with sudden onset of paralysis of ipsilateral facial musclesInflammatory injury, infection or degenerative disease
49Vestibulo-acoustic Nerve (VIII) Special somatic afferentVestibular NerveGives feedback about position of head in space and balanceAcoustic NerveHearingClinical InfoTests for equilibrium, vertigo or dizziness, nystagmus and hearing loss
50Glosso-pharyngeal Nerve (IX) General visceral afferentMediates general visceral sensation from soft palate, palatal arch, posterior 1/3 of tongue and carotid sinusGeneral visceral efferentSecretion from parotid gland (salivary gland)Special visceral afferentTaste sensation form posterior 1/3 of tongueSpecial visceral efferentContributes to swallowing through stylopharyngeus and upper pharyngeal constrictor fibers
51Clinical Info: Glosso-pharyngeal (IX) May be evident in dysphagia or loss of taste to posterior 1/3 of tongueLoss of gag reflexExcessive oral secretionsDry mouthNeed bilateral damage of nerve to have strong clinical signs
52Vagus Nerve (X) General visceral afferent General visceral efferent Sensation from pharynx, larynx, thorax, abdomenRegulates nausea, oxygen intake, lung inflationGeneral visceral efferentInnervates glands, cardiac muscles, trachea, bronchi, esophagus, stomach and intestineSpecial visceral afferentMediates taste sensation from posterior pharynx and epiglottisSpecial visceral efferentControls muscles of larynx, pharynx, soft palate for phonation, swallowing and resonance
53Clinical Info: Vagus Nerve (X) Bilateral lesion of the brainstem can be fatal due to respiratory involvementUnilateral lesion can result in ipsilateral paresis or paralysis of soft palate, pharynx and larynxPharyngeal BranchPharynx and soft palate involvementUvula pulled to unaffected side, bilateral soft palate droopsRecurrent Laryngeal BranchUnilateral: Paralysis of vocal foldsBilateral: Inspiratory stridor and aphonia
54Clinical Info: Vagus Nerve (X) Normal Soft PalateUnilateral ParalysisBilateral Paralysis
55Clinical Info: Vagus Nerve (X) Autonomic reflexes reducedAnesthesia of pharynx and larynx and loss of tasteSuperior Laryngeal BranchLoss of ability to change pitch
56Spinal Accessory Nerve (XI) General visceral efferentControls head position by controlling trapezius and sternocleidomastoid musclesClinical InformationAffects ability to control head movementsAsk patient to rotate head and note control
57Hypoglossal Nerve (XII) General somatic efferentControls tongue movementControls extrinsic and intrinsic muscles of tongue except palatoglossal (X)Eating, sucking and chewing reflexes
58Clinical Info: Hypoglossal (XII) LMN unilateral lesion can cause wrinkling and flaccidity of tone with atrophy over timeDysarthria and DysphagiaUnilateral UMN lesions do not have much affect as tongue is bilaterally innervatedAsk patient to complete oral motor movements
60Innervation of the tongue General (tactile, etc.)Special(taste)Glosso-pharyngeal(IX) NerveGlosso-pharyngeal(IX) NerveTrigeminal (V)NerveFacial (VII)Nerve
61Cranial Nerve Combinations More than one nerve involved with some structuresEyes muscle controlSensory fibers to tongueAnterior 2/3 special and general sensation: Facial and Trigeminal,Posterior 1/3special and general sensation: Glossopharyngeal
62Cranial Nerve Combinations Motor Nerve Supply to Soft Palate and PharynxVagus, Trigeminal and GlossopharyngealSensory Nerve Supply to Soft Palate and PharynxGlossopharyngeal, Vagus and Trigeminal
63Nerve Classifications This division give rise to a classification based on whether a nerve is:Afferent, efferent, or bothSomatic or visceral, or bothSpecial, general, or bothThe only combination that does not exist is: Special, somatic, efferent.
64Case # 1 Setting: Neonatal intensive care unit (NICU) Patient: Pt. is a two-day old male. Delivery was complex but completed with cesarean section, neurological exam suggests a right facial paralysis /s other prominent symptoms.What cranial nerve(s) is/are involved?Discuss the probable cause of the right facial paralysisIn what cases will the symptoms resolve?What are some possible current functional problems that may be present?What are some possible future functional problems?
65Case # 2 Setting: Out-patient clinic Patient: 64 y.o. male. Pt. is 18 months post-stroke. Neurological exam revealed: aphasia, dilated left pupil, left eye deviated downwards and lateral. Left eyelid droop.What cranial nerve is involved?What kind of a visual problem would this patient have?What can the patient do to compensate for the visual problem?Will this condition persist?In the long run, how will the brain compensate for this problem?Is it probable that the same lesion resulted in the visual problem and the aphasia?
66Case #3 Setting: Nursing home Patient: Pt. is a 78 y.o. female who has been residing at the nursing home for the last 3 years. She was originally admitted to the nursing home following amputation of both legs below the knee. This was necessary secondary to diabetes that results in gradual neuropathy and loss of vascular circulation in the extremities. A recent visit by the primary care physician revealed loss of sensation in the face secondary to progressive neuropathy. Her jaw is slightly deviated to the left.What cranial nerve is involved?How can you determine which afferent part of this cranial nerve is affected?What would cause the jaw to deviate to one side?Is this an upper or lower motor neuron problem?Will she improve? Why/why not?
67Case #4Setting: ICUPatient: 42 y.o. female. Patient was brought to the ER following a motor vehicle accident. She was comatose for 4 days but is now alert but not oriented. Pt. has multiple fractures including the: left tibia, left humerus and clavicle. Extensive facial bruising. MRI showed scattered bruising of the cortex and possible brain stem involvement. The neuro exam revealed severe aphonia, stridor, absent swallow reflex, drooping soft palate, no gag reflex.What cranial nerve is most likely affected?Is this an upper or lower motor problem?What are some other neurological symptoms that could be present?Would you recommend an oral diet for this patient? Why/why not?
68Case #5 Setting: Nursing home (SNF) Patient: Pt. is a 71 y.o. male who recently suffered a stroke. The MRI revealed multiple infarctions at the level of the basal ganglia and perhaps the brain stem. The neuro report from the hospital suggested that the patient has right lower facial droop, poor movement of most facial muscles, exaggerated smile, and excessive laughter or crying.Does this clinical picture agree with cranial nerve involvement? Why/why not?Is this an upper or lower motor neuron problem?Poor movement of most facial muscles would implicate what cranial nerve?
69VIII Injury: www. dizziness-and-hearing. com/testing/acoustic_reflexes VIII Injury:Central case example: A 40 year old man was well until he was involved in an auto accident. Two days later he developed diplopia and a rotatory type vertigo. On physical examination he had clear spontaneous nystagmus and mildly decreased hearing on the left side. Audiometry documented mildly impaired hearing on the left, but acoustic reflexes were abnormal with very rapid decay on the left side. Brainstem auditory evoked responses were abnormal on the left (neural response times to sounds). An MRI scan documented a lesion resembling an MS placque in his left cerebellar peduncle area, just behind the 8th nerve (see figure to right). His symptoms resolved spontaneously and he has had not further neurological complaints in 5 years of followup.