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CRANIAL NERVES
Dr. Hj. Meiti frida, Sp.S
Department of NeurologyMedical Faculty Andalas University -
Dr. M. Djamil Hospital
Padang
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What are cranial nerves ?
Is the twelve pairs of nerve that has itsorigin at the base of the brain
Not all of peripheral nerves , as the
olfactory bulb and optic nerve are in factextention of the Brain
The rest are differentiated from somatic
peripheral nerve, not only by theirlocations, but also they all have different/
spesific functions
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Cranial
Nerves
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Cranial
NerveNuclei
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Motoric
CranialNerves
Nuclei
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Sensoric
Cranial
Nerves
Nuclei
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Examples:Some function as special senses, like
Olfactory Olfactory nerve (I)
Vission Optic nerve(II)
Hearing and equilibrium
Stato-acustic nerve(VIII) Taste Trigemimenal-Fascial (V,VII)
Glossopharyngeal (IX)
Pure motor function
Trochlear (IV)
Abducens(VI)
Hypoglossal (XII)
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What is the use in understanding
cranial nerve
For localizing diseases at be the base of theskull or brainstem
This include knowledge of the anatomy of :
Base of the skull
Structures (nuclei and tracts) in the
brainstem
Help us in clinical diagnosis of brain death, inthe absence of EEG or other diagnosticapparatus
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Nuclei of Cranial nerves
Some nuclei serve only one nerve, likethe motor nuclei to the Abducens(VI)
nerve The Nucleus Solitarius takes fiber from
the anterior 2/3 of the tongue, through the5thnerve (Lingual branch), through the
chorda tympani, and the 7thnerve. Butfrom taste buds of the posterior 1/3,through the glossopharyngeal nerve
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Distribution Area of Cranial
nerves
While most extent just around the head,
Vagus (X), which is a parasympathic nerve sent
itsfibers to the chest and abdominal cavity,influencing the heart and the intestines until 2/3
of the colon.
The olfactory nerve on the other hand is only a
few millimeters long, penetrating the laminacribrosa, from the top of the nasal cavity to the
olfactory bulb
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I . Olfactory nerve
Brings the sense of smell from the nasal cavity
to the Olfactory bulb to the brain.
Because of so fine it is easily ruptured during ahead injury
The second cause of illness is frontal base
tumor and olfactory grove meningioma
Injury to this nerve make people complain of
loss of appetite
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N. I
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N. I
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II. Optic nerve The optic nerve serves our vision
Injury to the nerve may cause disturbance of ;Visual acuity : Sharpness of vision or
Visual field defect It depends on the cause of illness and the
location of injury
Papil edema : blurring of the optic disk on
ophthalmoscopic examination, is mostly asign of increased intracranial pressure
but can found also in optic nerveinflammation and malignant hypertension
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N. II
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Convergenceand
Accomodation
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III.Oculomotor nerve, IV. trochlear
nerve, VI. Abducens
All this three-nerve synchronously moveboth the eye-ball so that we will have
optimal vision The 3th and 4thnerve have their nuclei in
the Mesencephalon
The 6thnerve has its nuclei in the pons
The 6thnerve move the eye-ball to theside, an the 4thto the mid and downward.
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All other movements of the eye, including
moving the Eyelid upward, are the function ofthe 3rdnerve.
The 6thnerve travels the farthest on the baseof the skull, and is prone to paralysis during
chronic increased intracranial pressure In the cavernous sinus, those three nerves
travel together
All enter the optic cavity through the superior
fissure
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N. III, IV and VI
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3rdNerve Nuclei
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N. III, IV, V & VI
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Location of injury Total ophthalmoplegia, the most likely place
is in the cavernous sinus
Injury of the brainstem (mesencephalon)
usually gives only a partial 3rd
nerve palsy,but may be accompanied by contra-lateralhemiplegia
Injury of the side of the pons, may give 6th
nerve palsy, accompanied by 7th
nerve palsy,and contra-lateral hemiplegia
Diseases behind of the eye give also mostlypartial ophthalmoplegia
N III IV d VI
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N. III, IV, and VI
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Conjugate eye movement The left and right eye move synchronously, so
images is percieved as one in the brain.
The centre of lateral conjugate movement is at
the side of the 6thNerve, from where fibers go tothe Nuclei of the Medial Rectus, through the
Medial Lemniscus.
The center of horizontal movement is at thesuperior colliculus at the back of mesencephalon.
Damage of the Medial Lemniscus causes
Internuclear ophthalmoplegia
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Conjugate
movement
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V.Trigeminal Nerve This is the main sensory nerve of the face
(Portio Mayor), and inervates the muscles ofmastication (Portio Minor)
It has three branches: Ophthalmic, Maxilary,and Mandibular
Nerve from the taste buds travels first throughthe Lingual nerve, than through the ChordaTympani of the Fascial nerve (VII), to theSolitary Nuclei in the midbrain
Reversely, fibers to the submandibular andsubLingual glands, travel from the superiorSalivatory Nuclei, throught the 7thnerve(Intermedius) and Chorda Tympani .
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N. V
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VII. Fascial nerve
This nerve predominantly innervates thefascial muscles
Taste fibers and motor fiber to the Lacrimal ,and salivatory gland travel first with the fascial
motor fibers until the fascial channel Just after entering the internal acustic meatus
it gives branches to the lacrimal gland.
The taste and salivatory fibers cross to the
5thnerve through the chorda tympani.
Before exiting through the external acousticmeatus, it give a motoric branch to thestapedius muscle of the tympanic menbrane
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N. VII
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TastePathway
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GlandInnervation
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Central and Peripheral Fascial Palsies
In peripheral fascial palsies, the whole side of
the face is paralysed
There may also be Gustatory disturbances,and Tinnitus due to paralysis of the Stapedius
muscle
Central or Supra-Nuclear palsies like in strokes,
show only paralysis of the lower-half of the face,as the part of Nuclei serving the upperhalf is
bilaterally innervated.
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Central 7th palsy Peripheral 7th palsy
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VIII. Stato-acustic nerve This is a short nerve traveling with the 7th
nerve at the cerebello-pontine angle to theInternal auditory foramen. After entering thepetrosal bone it branches to the Cochleaand semicircular channels
In traumatic petrosal fractures, it may bedamaged together with the Fascial nerve
An acoustic sheet meningioma, may causean early rise of intracranial pressure
The acoustic portion, may also be damagedby Streptomycine
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N. VIII
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Central
Pathway of
Cochlear
Nerve
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Centralpathway of
vestibular
nerve
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IX. Glossopharyngeal
This is a predominantly sensory nerve , servingthe Pharynx and Larynx,
The Ambiguus Nuclei serve the muscles of the
pharynx and larynx, but the most dominant partpass through the Vagus nerve
It takes also nerves from the the Baro andChemo-receptors in the carotid Body,
The fibers of taste buds from the posterior 1/3of the tongue and Pharynx also pass throughthis nerve to the Solitary Nuclei
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N. IX
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X. Vagus Nerve
This is the most important nerve
From the Ambiguus Nuclei it sends motorfibers to most of muscle in the pharyx andLarynx
From the Parasympathic Dorsal Nuclei, sends
parasympatic branches to the Thoracic andAbdominal cavity.
The superior laryngeal nerve serves theexternal Vocal muscles, while the inferiorLaryngeal nerve after went down first andpassing the Brachial vessel on the right andthe aortic arc on the left went back upward tothe muscles of the Vocal cord
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N. X
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IX Accessory Nerve
This is a relative minor nerve
The cephalic part joint the Vagus nerve
The cervical part is an in fact somaticnerve, arises from the cervical medulla,
which past first upward, through the
Foramen Magnum, and then downward tothe Stercocleidomastoideus and
Trapezius muscles
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N. XI
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XII Hypoglossal Nerve
This is a motoric nerve serving the muscles ofthe tongue
We have external muscles, which move the
tongue to all directions, and internal muscleswhich can thicked or flatten or curl the tongue
In stroke, paralysis of one side of the Genio-hyoid muscle, causes the tongue protrude to
the paralysed side
In chronic peripheral nerve lesions the tongueflattened and Fasciculated
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N. XII
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