Title: Cranial Nerves
1Cranial Nerves
- Pundit Asavaritikrai, PhD, MD.
- Department of Anatomy, Faculty of Science
- Mahidol University
- neuronum_at_yahoo.com
2Overview
- Brain Stem
- Ascend./Descend. Pw
- Vital centres
- Consciousness
- Respiration
- CVS
- Cranial nerves
3Cranial 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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5Memorize 2-3 sections/division
6Midbrain
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8Pons
9Open Medulla
10Closed Medulla
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12CN I II
- CN I II
- brain extension
- not real nerves
- Special sensory afferents
13CN I Olfactory Nerve
- Olfaction
- Memory and Behavior
- Pheromones
- Anterior olfactory nucleus
- Amydala
- Piriform cortex
- Enthorhinal cortex
14CN II Optic Nerve
- Vision
- Intraocular movement ( III)
- Blinking ( V VII)
- Circadian rhythm
15The III, IV VI
16CN III Oculomotor Nerve
- Intraocular movement
- Autonomic
- Lens shape
- Pupil size
- Extrinsic Eye movement
- Coordinate with CN IV VI
17Control of Pupil Size
- Parasympathetic
- 1 Edinger-Westphal nuc.
- 2 ciliary ganglion
- pupillary constrictor
- fibers travel in outer margin of CN III
18Pupillary Light Reflex
- In CN II
- Pretectal area
- Posterior Com.
- Out CN III-EW nuc.
19Relative Afferent Pupillary Defect (RAPD) (CN II
? CN III)
20Adies Pupil
- Abnormally dilated pupil
- Can be tonic, sectional, vermiform iris
- Abnormal postganglionic parasympathetic fibers
21Argyll-Robertsons Pupil
- Associated with Syphillis
- Normal pupil accommodation
- Does not constrict to light
- Pretectal area damage
- Prostitutes pupil Accommodate but does not
react
22Sympathetic 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
23Ptosis
- Abnormal CN III
- LPS
- NMJ (Myasthenia)
- Sympathetic
- Superior tarsal m.
- Does not involve CN VII (??????????)
24CN III, IV, VI
25CN III, IV, VI
- Function
- Coordination
- Control of coordination (conjugation)
26MLF (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
27Disorders of the MLF
- Internuclear Ophthalmoplegia
28CN III, IV, VICoordination of Eye Movements
29Coordination of Eye Movements
- Conjugate eye movement
- Dysconjugate eye movement (vergence)
30Dysconjugate 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)
31CN III, IV, VISupranuclear Control of Eye
Movements
32Supranuclear 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
33Dysconjugated Eye Movement
- No MLF
- Near vision
- Accommodation
- Pupil constriction
- Vergence
34Conjugate Eye Movements
- Yoking mechanism
- Via MLF
- E.g. CN VI ? contralat. CN III
- Clinical use
- e.g. Internuclear ophthalmoplegia
351. 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
362. 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
373. 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
383. 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
39Vestibulo-ocular Reflex
- Contralateral CN VI n.
- From CN VI n
- ? ipsi. CN III n
40Nystagmus
41Vestibular 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
42Nystagmus
- VOR occurs
- in slow phase
- Fast phase
- is mediated by
- Superior collic.
43p398
44Dolls eye phenomenon Caloric test
45The CN V
- Facial sensation
- Mastication
- Jaw jerk reflex
46CN V Sensory Distribution
47Jaw Jerk Reflex
- In CN V3 (s)
- Mesencephalic Nc
- Out CN V3 (m)
- Bilat.
- Motor nuc. Of V
48CN VII Facial Nerve
49Cranial Nerve Motor Nuclei A group of Lower
Motor Neurons (LMN)
50Taste Gustation
51UMN lesion of Facial Nerve
- Upper Face
- Dual innervation
- Lower Face
- Contralateral Innervation
- UMN lesion of CN VII
- Contralateral paralysis of (only) the lower face
52Corneal Blink Reflex
53CN VIII Vestibulo-Cochlear Nerve
54CN 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
55CN 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)
56CN IX Glossopharyngeal Nerve
57CN X Vagal Nerve XI Spinal Accessory Nerve
58Gag Reflex
59CN XI, XII
60CN XII Hypoglossal Nerve
61References
- 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.
62Fathers of Neuroscience
- Camillo Golgi
- (1843-1926)
- Santiago Ramon y Cajal
- (1852-1934)
63Father of Neurosurgery Father of Neurology
- Harvey Williams Cushing (1869-1939)
- Jean-Martin Charcot
- (1825-1893)
64A 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