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Cranial Nerves Pundit Asavaritikrai, PhD, MD. Department of Anatomy, Faculty of Science Mahidol University

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Presentation on theme: "Cranial Nerves Pundit Asavaritikrai, PhD, MD. Department of Anatomy, Faculty of Science Mahidol University"— Presentation transcript:

1 Cranial Nerves Pundit Asavaritikrai, PhD, MD. Department of Anatomy, Faculty of Science Mahidol University

2 Overview Brain Stem –Ascend./Descend. P’w –Vital centres Consciousness Respiration CVS –Cranial nerves

3 Cranial Nerves & Cranial Nerve Reflexes CN I CN II CN III, IV, & VI CN V CN VII, CN VIII CN IX & X CN XI CN XII

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5 Memorize 2-3 sections/division

6 Midbrain

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8 Pons

9 Open Medulla

10 Closed Medulla

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12 CN I & II –brain extension –not real nerves –Special sensory afferents

13 CN I Olfactory Nerve Olfaction Memory and Behavior Pheromones Anterior olfactory nucleus Amydala Piriform cortex Enthorhinal cortex

14 CN II Optic Nerve Vision Intraocular movement (+ III) Blinking (+ V & VII) Circadian rhythm

15 The III, IV & VI

16 CN III Oculomotor Nerve Intraocular movement –Autonomic Lens shape Pupil size Extrinsic Eye movement –Coordinate with CN IV & VI

17 Control of Pupil Size Parasympathetic #1 = Edinger-Westphal nuc. #2 = ciliary ganglion –pupillary constrictor –fibers travel in outer margin of CN III

18 Pupillary Light Reflex In: CN II –Pretectal area –Posterior Com. Out: CN III-EW nuc.

19 Relative Afferent Pupillary Defect (RAPD) (CN II  CN III)

20 Adie’s Pupil Abnormally dilated pupil Can be tonic, sectional, vermiform iris Abnormal postganglionic parasympathetic fibers

21 Argyll-Robertson’s Pupil Associated with Syphillis –Normal pupil accommodation –Does not constrict to light –Pretectal area damage Prostitute’s pupil = Accommodate but does not react

22 Sympathetic #1 = T1 lateral neurons #2 = SCG –Pup. dilator, tarsus m, sweat gl. Defects: Horner’s syndrome ( เล็ก แห้ง ตก ไม่งอก ) Causes: –pulmonary apex –lateral medulla (+vestibular defects; vertigo) = Wallenberg syndrome Sympathetic Control of Pupil

23 Ptosis Abnormal CN III –LPS –NMJ (Myasthenia) Sympathetic –Superior tarsal m. Does not involve CN VII ( ปิดไม่สนิท )

24 CN III, IV, & VI

25 CN III, IV, VI Function Coordination Control of coordination (conjugation)

26 MLF (medial longitudinal fasciculus) Internuclear connection Nonvestibular pathways (among CN nuclei) –VI-contralateral III –III-VII, VII-V, V-XII, XII-VII Vestibular pathways: –Eye –Ear –Neck –Limb extensors p389

27 Disorders of the MLF Internuclear Ophthalmoplegia

28 CN III, IV, & VI: Coordination of Eye Movements

29 Coordination of Eye Movements Conjugate eye movement Dysconjugate eye movement (vergence)

30 Dysconjugate Eye Movement Vergence –‘dysconjugate but still coordinate’ –involving vergence center in the midbrain, no MLF Near triad (Accommodation) –Stimulus: Near object –Executor: cerebral cortex  SC  pretectal area Ocular vergence (midbrain RF, both sides) Lens rounding up (EW, both sides) Pupil constriction (EW, both sides)

31 CN III, IV, & VI: Supranuclear Control of Eye Movements

32 Supranuclear Control Idea  there must be some control above III, IV, VI (= supranuclear control) 1. Gaze –Saccades (quick) –Smooth persuit (slow) –Foveation 3. Vestibulo-ocular reflex 4. Nystagmus

33 Dysconjugated Eye Movement No MLF Near vision –Accommodation –Pupil constriction –Vergence

34 Conjugate Eye Movements Yoking mechanism Via MLF E.g. CN VI  contralat. CN III Clinical use: e.g. Internuclear ophthalmoplegia

35 1. Smooth Persuit Conjugate movement that maintains foveation of a moving object Can be Voluntary or Involuntary Mechanisms –Stimuli = retinal slip –Processor = Area 19 & 39 (Angular gyrus) –Executor = Area 8    ipsilateral CN VI  contralateral CN III

36 2. Reactive gaze (Saccadic eye movement) Rapid jerky involuntary conjugate movement (Faster than smooth persuit) Stimuli = changing point of fixation, light, noise, noxious stimuli –Processor = Area 7 (parietal) –Executor = Area 8 & SC  contralat. PPRF paramedian pontine reticular formation (pontine gaze centers)  PPRF excites CN VI  LR e.g. Lt. Frontal eye field excites contralateral CN VI Clinical use –eye movements towards the side of lesion ( ตามองฟ้องลีชั่น ) p394

37 3. Vestibulo-Ocular Reflex (VOR) Conjugate movement that maintains eye position while head moves ~ involuntary/reflexive smooth persuit –Stimuli = warm water, head turning to that side –Processor & Executor = vestibular nuc.  inhibit ipsilateral CN VI  inhibit MLF contralateral CN III

38 3. Vestibulo-Ocular Reflex (VOR) Ex. Stimulation of Rt. Vest. Nuc.  inhibit Rt. CN VI & LR  eyes deviate to left Ex. Inhibition of Rt. Vest. Nuc by: –cold water in the Rt. –turning head to the Lt. –lesion of Rt. vestibular input  Rt LR turns the eye to the Rt Clinical use: –Doll’s eye reflex

39 Vestibulo-ocular Reflex Contralateral CN VI n. From CN VI n –  ipsi. CN III n

40 Nystagmus Vestibular Optokinetic

41 Vestibular Nystagmus Relationship between –smooth persuit (slow phase), and –saccadic eye movement (fast phase) ‘E.g. Right nystagmus refers to the fast phase of saccadic eye movement to the right’ Types: –Physiologic nystagmus: Optokinetic nystagmus Vestibular nystagmus Cold caloric testing*  slow eye (VOR) will move the eyes to the side of cold water  Saccades will move the eyes to opposite side of cold water (COWS) –Pathologic nystagmus: Nystagmus at rest Positional nystagmus Vertical nystagmus Pendular nystagmus

42 Nystagmus VOR occurs –in slow phase Fast phase –is mediated by –Superior collic.

43 p398

44 Doll’s eye phenomenon & Caloric test

45 The CN V Facial sensation Mastication Jaw jerk reflex

46 CN V: Sensory Distribution

47 Jaw Jerk Reflex In: CN V3 (s) Mesencephalic Nc Out: CN V3 (m) Bilat. Motor nuc. Of V

48 CN VII Facial Nerve GSA SSA SSE* GVE

49 Cranial Nerve Motor Nuclei = A group of Lower Motor Neurons (LMN)

50 Taste: Gustation

51 UMN lesion of Facial Nerve Upper Face: –Dual innervation Lower Face: –Contralateral Innervation *UMN lesion of CN VII –Contralateral paralysis of (only) the lower face

52 Corneal Blink Reflex

53 CN VIII Vestibulo-Cochlear Nerve

54 CN VII, IX, X Mixed Efferents: SVE: –CN VII motor nuclei: Face Bilat. & Contralat. Ctc. Innerv. Defects: facial palsy –Ambiguus nuclei (IX & X): Pharynx & Larynx Bilateral cortical innervation Defects: dysphagia GVE: –Sup. & Inf. Salivatory nucleus –Dorsal motor nucleus of X

55 CN VII, IX, X Afferents: GSA: pharynx/ear SVA: taste –Solitary nucleus & tract (VII, IX, X) GVA: pressure receptor, thoracic, abdomen –Medullar reticular formation IX baroreceptors (carotid a.) X baroreceptors (LV, aortic arch)

56 CN IX Glossopharyngeal Nerve

57 CN X Vagal Nerve & XI Spinal Accessory Nerve

58 Gag Reflex

59 CN XI, XII

60 CN XII Hypoglossal Nerve

61 References Nadeau SE, et al, Medical Neuroscience 1 st Ed., 2004: pp (Cycle 8), Saunders. Haines DE, et al, Fundamental Neuroscience for Basic and Clinical Application, 3 rd Ed., 2006: pp Elsevier.

62 Fathers of Neuroscience Camillo Golgi ( ) Santiago Ramon y Cajal ( )

63 Father of Neurosurgery & Father of Neurology Harvey Williams Cushing ( ) Jean-Martin Charcot ( )

64 A CLINICAL LESSON AT "LA SALPETRIERE." Joseph Babinski, Georges Gilles de la Tourette, Henri Parinaud Pierre Janet, William James, Pierre Marie, Albert Londe, Sigmund Freud, Charles-Joseph Bouchard, Axel Munthe, and Alfred Binet


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