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Cranial Nerves

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Title: Cranial Nerves


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

2
Overview
  • Brain Stem
  • Ascend./Descend. Pw
  • 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

4
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5
Memorize 2-3 sections/division
6
Midbrain
7
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8
Pons
9
Open Medulla
10
Closed Medulla
11
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12
CN I II
  • 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
Adies Pupil
  • Abnormally dilated pupil
  • Can be tonic, sectional, vermiform iris
  • Abnormal postganglionic parasympathetic fibers

21
Argyll-Robertsons Pupil
  • Associated with Syphillis
  • Normal pupil accommodation
  • Does not constrict to light
  • Pretectal area damage
  • Prostitutes pupil Accommodate but does not
    react

22
Sympathetic Control of Pupil
  • Sympathetic
  • 1 T1 lateral neurons
  • 2 SCG
  • Pup. dilator, tarsus m, sweat gl.
  • Defects Horners syndrome
  • (???? ???? ?? ??????)
  • Causes
  • pulmonary apex
  • lateral medulla
  • (vestibular defects vertigo) Wallenberg
    syndrome

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

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

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27
Disorders of the MLF
  • Internuclear Ophthalmoplegia

28
CN III, IV, VICoordination 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, VISupranuclear 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
    (???????????????)

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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
  • Dolls 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
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44
Dolls 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 1st Ed.,
    2004 pp 358-418 (Cycle 8), Saunders.
  • Haines DE, et al, Fundamental Neuroscience for
    Basic and Clinical Application, 3rd Ed., 2006 pp
    209-228 Elsevier.

62
Fathers of Neuroscience
  • Camillo Golgi
  • (1843-1926)
  • Santiago Ramon y Cajal
  • (1852-1934)

63
Father of Neurosurgery Father of Neurology
  • Harvey Williams Cushing (1869-1939)
  • Jean-Martin Charcot
  • (1825-1893)

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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