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
(No Transcript)
5
Memorize 2-3 sections/division
6
Midbrain
7
(No Transcript)
8
Pons
9
Open Medulla
10
Closed Medulla
11
(No Transcript)
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

p389
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
  (???????????????)

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
• 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
p398
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