The document discusses the cranial nerves. It notes that there are 12 pairs of cranial nerves, with 10 pairs attached to the brain stem and 2 attached to the cerebrum. It provides details on the names, functions and lesions associated with some of the main cranial nerves including: - Olfactory nerve - Special sensory, provides smell - Optic nerve - Special sensory, provides vision - Oculomotor nerve - Motor and parasympathetic, controls eye movements and pupil constriction - Trigeminal nerve - Mixed nerve with sensory, motor and parasympathetic functions including face sensation and muscles of mastication.

2.  1212 pairs, (two are attached to the cerebrum andpairs, (two are attached to the cerebrum and 1010 areare
attached to the brain stemattached to the brain stem
 Nine are attached to the ventral surface of the brainNine are attached to the ventral surface of the brain
stem, while one is attached to the back of the midbrainstem, while one is attached to the back of the midbrain
(Trochlear).(Trochlear).
 They leave the cranial cavity by passing through smallThey leave the cranial cavity by passing through small
foramina in the skull bonesforamina in the skull bones
 Both ‘names’ and ‘numbers’ are used to identify themBoth ‘names’ and ‘numbers’ are used to identify them
 Their names indicate either their distribution or theirTheir names indicate either their distribution or their
functionfunction
 Their numbers (Their numbers (ROMAN numerals)ROMAN numerals) indicate the orderindicate the order
in which the nerves arise from the brain.in which the nerves arise from the brain.

3. •..Like all nerves, cranial nerves are made up ofLike all nerves, cranial nerves are made up of
bundles of axonsbundles of axons
Cranial nerves may be sensory, or motor, or mixed,Cranial nerves may be sensory, or motor, or mixed,
and may contain somatic and/or autonomic fibers.and may contain somatic and/or autonomic fibers.
CranialCranial NervesNerves

4. I OlfactoryOlfactory
II OpticOptic
III OcculomotorOcculomotor
IV TrochlearTrochlear
V TrigeminalTrigeminal
V1: OphthalmicV1: Ophthalmic
V2: MaxillaryV2: Maxillary
V3: MandibularV3: Mandibular
VI AbducentAbducent
VII FacialFacial
VII
I
VestibulocochlearVestibulocochlear
(Statoacoustic)(Statoacoustic)
IX GlossopharyngealGlossopharyngeal
X VagusVagus
XI AccessoryAccessory
• CranialCranial partpart
• SpinalSpinal partpart
XII HypoglossalHypoglossal

5. NERVE FORAMEN NERVE FORAMEN
1st Cribriform plate
of ethmoid
7th Internal acoustic meatus,
stylomastoid foramen
2nd Optic canal 8th Internal acoustic
meatus
3rd
Superior orbital
fissure
9th
Jugular foramen
4th
5th(V1) 10th
6th
5th(V2) Foramen rotundum 11th
5th(V3) Foramen ovale 12th Hypoglossal canal
Foramina of ExitForamina of Exit

8.  Type:
 Special sensory
 Function:
 Smell
 Lesion :
 Leads to loss of
sense of smell,
called anosmia

9.  Type:
 Special sensory
 Function:
 Vision
 Lesion:
 Leads to visual field
defects and loss of
visual acuity.
 A defect of vision is
called anopsia

10.  TypeType::
 Motor & ParasympatheticMotor & Parasympathetic
 11-- OculomotorOculomotor NucleusNucleus
 lies close to the apex of thelies close to the apex of the
periaqueductal grey mater ofperiaqueductal grey mater of
the midbrain.the midbrain.
 It lies at the level of theIt lies at the level of the
superior colliculus.superior colliculus.
 Its efferent fibers run in the 3Its efferent fibers run in the 3rdrd
CN to LPS and all extraocularCN to LPS and all extraocular
musclesmuscles except LR6 & SO4.except LR6 & SO4.
 It emerges in theIt emerges in the
interpedunclar fossa medial tointerpedunclar fossa medial to
the crus cerebrithe crus cerebri..

11. Function:Function:
Elevation of the upper eyelid,Elevation of the upper eyelid,
Movements of eyeball,Movements of eyeball,
Constriction of pupil andConstriction of pupil and
Accommodation for near visionAccommodation for near vision
2-Edinger-Westphal2-Edinger-Westphal NucleusNucleus,,
lies close to the oculomotorlies close to the oculomotor
nucleus.nucleus.
Gives preganglionic fibers to theGives preganglionic fibers to the
ciliary ganglion.ciliary ganglion.
Many of the preganglionic fibersMany of the preganglionic fibers
traverse thetraverse the Red NucleusRed Nucleus
Postganglionic fibers run in thePostganglionic fibers run in the
short ciliary nerve.short ciliary nerve.
It supply the constrictor pupillaeIt supply the constrictor pupillae
and ciliary muscles.and ciliary muscles.

12.  Lesion results in:Lesion results in:
 Lateral squintLateral squint
 PtosisPtosis
 DiplopiaDiplopia
 Pupillary dilatationPupillary dilatation
 Loss ofLoss of
accommodationaccommodation
 Impaired downwardImpaired downward
& outward& outward
movement of the eyemovement of the eye
ball on the damagedball on the damaged
side.side.

13.  Trochlear nucleusTrochlear nucleus
 Lies in the periaqueductalLies in the periaqueductal
grey of the midbrain at thegrey of the midbrain at the
level of thelevel of the inferiorinferior
colliculuscolliculus..
 Axons pass dorsally andAxons pass dorsally and
cross the midline.cross the midline.
 It courses around crusIt courses around crus
cerebricerebri between posterior
cerebral and superior
cerebellar arteries.

14.  It runs in the lateralIt runs in the lateral
wall of the cavernouswall of the cavernous
sinus then to SOF.sinus then to SOF.
 It suppliesIt supplies SO4SO4
 It moves the eyeIt moves the eye
downwards anddownwards and
medially.medially.
 Lesion:
 diplopia, & difficulty in
walking downstairs

15.  Type:Type:
 MixedMixed
 Three divisionsThree divisions::
 V1:Ophthalmic (sensory)V1:Ophthalmic (sensory)
 V2:Maxillary (sensory)V2:Maxillary (sensory)
 V3: MandibularV3: Mandibular (mixed)(mixed)
 Function:Function:
 Sensory:Sensory:
 Carries generalCarries general
sensations (pain, touch,sensations (pain, touch,
temperature, pressure,temperature, pressure,
vibration) from the facevibration) from the face
& ant. scalp, orbit, nasal& ant. scalp, orbit, nasal
and oral cavity, &and oral cavity, &
anterior 2/3 of tongueanterior 2/3 of tongue

16.  One large sensory ganglionOne large sensory ganglion
located in the middle craniallocated in the middle cranial
fossa, at the apex of petrousfossa, at the apex of petrous
temporal bone, its centraltemporal bone, its central
process go to:process go to:
 TrigeminalTrigeminal SensorySensory
Nucleus.Nucleus.
 It extends all through theIt extends all through the
brain stem & upper cervicalbrain stem & upper cervical
segmentssegments
 It is formed of 3 subdivisionsIt is formed of 3 subdivisions::
 1-1- Chief or Main or principalChief or Main or principal
sensory nucleus:sensory nucleus:
 Lies in pontine tegmentumLies in pontine tegmentum
close to the entry of 5close to the entry of 5thth
CN.CN.
 It receives touch andIt receives touch and
pressurepressure..

17.  2-Spinal nucleus &2-Spinal nucleus &
tract of the trigeminaltract of the trigeminal
nerve;nerve;
 ExtendsExtends caudally in thecaudally in the
medulla and uppermedulla and upper
cervical segments.cervical segments.
 It is continuous belowIt is continuous below
the with substantiathe with substantia
gelatinosa ofgelatinosa of RolandoRolando..
 It receives pain &It receives pain &
temperature sensations.temperature sensations.
 From the face, scalp,From the face, scalp,
orbit, nasal and oralorbit, nasal and oral
cavities, and anterior 2/3cavities, and anterior 2/3
of the tongueof the tongue

18.  3- Mesencephalic
Nucleus: extends
rostrally into the
midbrain.
 It carries proprioceptive
afferent fibers from the
muscles of mastication
and from the TMJ.
 The cell bodies of all
sensations are present in
the trigeminal ganglion,
Except proprioceptive
sensation which lies in
the CNS.

19.  Axons arising from theAxons arising from the
trigeminal nucleus decussatetrigeminal nucleus decussate
to form the contralateralto form the contralateral
trigeminal tract, or lemniscustrigeminal tract, or lemniscus
(2(2ndnd
order neuron)order neuron)
 This terminates in theThis terminates in the
contralateralcontralateral PMVNPMVN ofof
thalamus, then to parietalthalamus, then to parietal
sensory cortex.sensory cortex.
 The trigeminal nucleus sendsThe trigeminal nucleus sends
fibers to the cerebellum fromfibers to the cerebellum from
which, the cerebellum sendwhich, the cerebellum send
fibers to thefibers to the facial nucleusfacial nucleus
which mediate facialwhich mediate facial
grimacing and eye closuregrimacing and eye closure
(corneal reflex).(corneal reflex).

20.  Motor nucleus ofMotor nucleus of
trigeminal nervetrigeminal nerve
 It lies in pontineIt lies in pontine
tegmentum medial totegmentum medial to
the main sensorythe main sensory
nucleus.nucleus.
 Fibers runs in the motorFibers runs in the motor
root of the trigeminal,root of the trigeminal,
then they join thethen they join the
mandibular nerve.mandibular nerve.
 It supplyIt supply 8 (4+4)8 (4+4) musclesmuscles
which developed fromwhich developed from
the 1the 1stst
pharyngeal arch.pharyngeal arch.

21.  Lesion:Lesion:
 Loss of generalLoss of general
sensations in the areasensations in the area
of distribution,of distribution,
 Paralysis of theParalysis of the
muscles of masticationmuscles of mastication

22.  Compression, inflammation or degeneration of
the 5th
cranial nerve may result in a condition
called trigeminal neuralgia or tic douloureux.
 This condition is characterized by recurring
episodes of intense stabbing , excoriating pain
radiating from the angle of the jaw along a
branch of trigeminal nerve.
 Usually involves maxillary & mandibular
nerves, rarely in the ophthalmic division

23.  TypeType::
 MotorMotor
 SuppliesSupplies: Lateral rectus.: Lateral rectus.
 FunctionFunction: moves the eye: moves the eye
laterallylaterally
 Lesion:Lesion:
 Medial squint, diplopia,Medial squint, diplopia,
loss of movement of the eyeloss of movement of the eye
laterally beyond thelaterally beyond the
midpoint.midpoint.

24.  Abducent NucleusAbducent Nucleus
 Lies inLies in caudal Ponscaudal Pons
beneath the floor of thebeneath the floor of the
44thth
ventricle.ventricle.
 Fibres pass ventrally andFibres pass ventrally and
emerge from theemerge from the Ponto-Ponto-
medullarymedullary junctionjunction
between the pyramidbetween the pyramid
and the Pons.and the Pons.
 Abducent nerve passesAbducent nerve passes
in the lateral wall of thein the lateral wall of the
cavernouscavernous sinussinus thenthen
through thethrough the SOFSOF toto
supply the lateral rectussupply the lateral rectus

25.  Type:Type:
 Motor,Motor, special sensoryspecial sensory,,
parasympatheticparasympathetic
 FunctionFunction::
 Motor to muscles of facialMotor to muscles of facial
expression (2expression (2ndnd
pharyngealpharyngeal
arch, lacrimal gland, nasalarch, lacrimal gland, nasal
and oral mucous membraneand oral mucous membrane
submandibular & sublingualsubmandibular & sublingual
salivary glands, taste fiberssalivary glands, taste fibers
from the anterior 2/3 of thefrom the anterior 2/3 of the
tonguetongue
 Lesion:Lesion:
 Bell’s palsy, loss of taste fromBell’s palsy, loss of taste from
anterior 2/3 of tongue, loss ofanterior 2/3 of tongue, loss of
Lacrimation and salivationLacrimation and salivation

26.  It joins the brain stem in theIt joins the brain stem in the
cerebellopontine angle.cerebellopontine angle.
 It consists of two roots:It consists of two roots:
 11-- Lateral rootLateral root (nervous(nervous
intermedius), contains sensoryintermedius), contains sensory
&& parasympathetic fibersparasympathetic fibers..
 22-- Medial rootMedial root containscontains motormotor
fibersfibers
 Sensory fibers, carry taste fromSensory fibers, carry taste from
the anterior 2/3the anterior 2/3rdrd
of tongue,of tongue,
floor of mouth and palate,floor of mouth and palate,
which endwhich end solitary nucleussolitary nucleus..
 It also carry cutaneousIt also carry cutaneous
sensation from part of externalsensation from part of external
ear, which end in theear, which end in the spinalspinal
nucleus of 5nucleus of 5thth
CNCN

27.  Motor nucleus of facialMotor nucleus of facial
nervenerve
 It lies in theIt lies in the caudal Ponscaudal Pons..
 The axons pass dorsally,The axons pass dorsally,
looping around abducenslooping around abducens
nucleus beneath the floor ofnucleus beneath the floor of
44thth
ventricle.ventricle.
 Axons pass in the motor rootAxons pass in the motor root
77thth
CNCN
 N.B.N.B. Corticobulbar fibersCorticobulbar fibers
project bilaterally to theproject bilaterally to the
upper part of the motor 7upper part of the motor 7thth
nucleus, and project to thenucleus, and project to the
lower part of the nucleuslower part of the nucleus
from the opposite side only.from the opposite side only.

28.  Damage to facial nerve resultsDamage to facial nerve results
in paralysis of facial muscles:in paralysis of facial muscles:
Facial (Bell’s palsy);lowerFacial (Bell’s palsy);lower
motor neuron lesion (wholemotor neuron lesion (whole
face affected)face affected)
 NB. In upper motor neuronNB. In upper motor neuron
lesion (upper face is intact) .lesion (upper face is intact) .
 Face is distorted: drooping ofFace is distorted: drooping of
lower eyelid, sagging of thelower eyelid, sagging of the
angle of the mouth, dribblingangle of the mouth, dribbling
of saliva, loss of facialof saliva, loss of facial
expressions, loss of chewing,expressions, loss of chewing,
blowing, sucking, unable toblowing, sucking, unable to
show teeth or close the eye onshow teeth or close the eye on
affected sideaffected side

29.  Superior salivatorySuperior salivatory
nucleus.nucleus.
 Lies in the Pons.Lies in the Pons.
 Axons run in the nervousAxons run in the nervous
intermedius, to theintermedius, to the
parasympathetic ganglia:parasympathetic ganglia:
 1- Submandibular1- Submandibular
ganglion:ganglion:
 Postganglionic fibers passPostganglionic fibers pass
to submandibular &to submandibular &
sublingual salivary gland.sublingual salivary gland.
 2- Pterygopalatine2- Pterygopalatine
ganglion:ganglion: PostganglionicPostganglionic
fibers pass to Lacrimalfibers pass to Lacrimal
gland, nasal and oralgland, nasal and oral
mucous membrane.mucous membrane.

30.  Type:
 Special sensory
 Function:
 Vestibular part:
conveys impulses
associated with
balance of body
 Cochlear part:
conveys impulses
associated with
hearing
 Lesion: loss of
hearing, tinnitus,
vertigo, dizziness,
ataxia and nystagmus

31.  TypeType:: MotorMotor,, SensorySensory
(general & special)(general & special)
parasympatheticparasympathetic
 FunctionFunction: motor: motor toto
(Stylopharyngeus), &(Stylopharyngeus), &
parotid gland,parotid gland,
 carries taste fibers fromcarries taste fibers from
posterior 1/3 of tongue,posterior 1/3 of tongue,
general sensations fromgeneral sensations from
pharynx & palate.pharynx & palate.
 Lesion:Lesion:
 Dysphagia (difficultDysphagia (difficult
swallowing), loss ofswallowing), loss of
sensation from throat,sensation from throat,
loss of parotid secretionloss of parotid secretion
and loss of taste fromand loss of taste from
posterior 1/3 of the tongueposterior 1/3 of the tongue

32.  TypeType::
 MotorMotor (+cranial part of(+cranial part of
accessory nerve),accessory nerve),
 SensorySensory (general &(general &
special),special),
 ParasympatheticParasympathetic
 FunctionFunction::
 supplies visceralsupplies visceral
muscles, glands of GIT,muscles, glands of GIT,
muscles of the larynx andmuscles of the larynx and
pharynx, taste buds onpharynx, taste buds on
the base of tongue,the base of tongue,
sensations from thesensations from the
viscera Carotid sinus andviscera Carotid sinus and
carotid bodycarotid body

33.  Lesion Leads to:Lesion Leads to:
 Loss of gag reflexLoss of gag reflex
 Difficulty in swallowingDifficulty in swallowing
 Loss of sensations fromLoss of sensations from
the abdominal viscerathe abdominal viscera
 Loss of taste from theLoss of taste from the
base of tongue &base of tongue &
epiglottisepiglottis
 Hoarseness or loss ofHoarseness or loss of
voicevoice
 GastrointestinalGastrointestinal
dysfunctiondysfunction
 Blood pressureBlood pressure
anomalies (with CN IX),anomalies (with CN IX),
fatal if both are cutfatal if both are cut

34.  Type:Type:
 Motor,Motor,
 It has two parts:It has two parts:
 cranial & spinalcranial & spinal
 Function:Function:
 CranialCranial part: unitespart: unites
with the vagus andwith the vagus and
supplies voluntarysupplies voluntary
muscles of larynx,muscles of larynx,
pharynx and esophaguspharynx and esophagus
 SpinalSpinal part: suppliespart: supplies
(sternomastoid &(sternomastoid &
Trapezius)Trapezius)
 Lesion:Lesion: Difficulty inDifficulty in
swallowing, and speech.swallowing, and speech.
Inability to turn the head,Inability to turn the head,
and raise the shoulder.and raise the shoulder.

35.  Type:Type:
 MotorMotor
 Function:Function:
 Motor to all muscles ofMotor to all muscles of
the tongue exceptthe tongue except
palatoglossuspalatoglossus.. AllowsAllows
movements of tonguemovements of tongue
during speech andduring speech and
swallowingswallowing
 Lesion:Lesion: difficulty indifficulty in
chewing and speech.chewing and speech.
 The tongue paralyses,The tongue paralyses,
atrophies, becomesatrophies, becomes
shrunken and furrowedshrunken and furrowed
on the affected side, andon the affected side, and
on protrusion it deviateson protrusion it deviates
to the affected sideto the affected side

36.  Causes:
 Severe head injuries, skull bone
fractures or penetrating wounds
 Brain lesions
 Compression due to raised intracranial
pressure (due to any space occupying
lesion e.g. tumor, hematoma, or CSF
obstruction )
 Cavernous sinus thrombosis

37.  Compression of
abducent nerve
and internal
carotid artery

38.  The integrity of nerves is assessedThe integrity of nerves is assessed
by examining the:by examining the:
The sensations in the area ofThe sensations in the area of
distributiondistribution
Action of musclesAction of muscles
Integrity of reflexesIntegrity of reflexes
Secretory activity of glandsSecretory activity of glands

39.  Pupillary (light) CN 2, 3Pupillary (light) CN 2, 3
 Accommodation CN 2, 3Accommodation CN 2, 3
 Corneal (Blinking) CN 5,7Corneal (Blinking) CN 5,7
 Lacrimation 5, 7 (stimulus may be visual or evenLacrimation 5, 7 (stimulus may be visual or even
thought or emotions)thought or emotions)
 Salivation CN 1, 2, 5, 7, 9 (stimulus may beSalivation CN 1, 2, 5, 7, 9 (stimulus may be
olfactory, visual, taste, or even thought of food)olfactory, visual, taste, or even thought of food)
 Sneezing CN 1, 5, 9, 10, 11, phrenic, intercostalsSneezing CN 1, 5, 9, 10, 11, phrenic, intercostals
 Vomiting CN 1, 5, 7, 9 (stimulus may be olfactory,Vomiting CN 1, 5, 7, 9 (stimulus may be olfactory,
visual, taste, or even thought)visual, taste, or even thought)

40.  Yawning CN 5, 7, phrenic, intercostalYawning CN 5, 7, phrenic, intercostal
 Swallowing CN 5, 7, 9, 10, 11, 12Swallowing CN 5, 7, 9, 10, 11, 12
 Jaw jerk CN 5Jaw jerk CN 5
 Stapedial CN 8, 7Stapedial CN 8, 7
 Cough CN 9, 10, 11, phrenic, intercostalsCough CN 9, 10, 11, phrenic, intercostals
 Gag CN 9, 10Gag CN 9, 10
 Carotid sinus reflex CN 9, 10Carotid sinus reflex CN 9, 10

41. Olfactory nerveOlfactory nerve::
Ask the patient to identify items with veryAsk the patient to identify items with very
specific odors,(e.g.. coffee, alcohol, perfume),specific odors,(e.g.. coffee, alcohol, perfume),
placed under the nose.placed under the nose.
Each nostril isEach nostril is tested separatelytested separately
Optic nerveOptic nerve::
Ask the patient to read an eye chart.Ask the patient to read an eye chart.
 Peripheral vision is tested by detecting object orPeripheral vision is tested by detecting object or
movement from corners of the eyesmovement from corners of the eyes
Occulomotor nerveOcculomotor nerve::
Note the ability to move each eye upward, downwardNote the ability to move each eye upward, downward
and inward by asking the person to follow a targetand inward by asking the person to follow a target
moved by the examiner.moved by the examiner.
 Also examine the constriction of pupil &Also examine the constriction of pupil &
accommodationaccommodation

43.  Trochlear:Trochlear:
 Note the ability to move each eye downward andNote the ability to move each eye downward and
inwardinward
 Trigeminal nerveTrigeminal nerve::
 General sensations on face are tested by using a pinGeneral sensations on face are tested by using a pin
and a wisp of cotton.and a wisp of cotton.
 Blink reflex is tested by touching the cornea of theBlink reflex is tested by touching the cornea of the
eye with a cotton wisp.eye with a cotton wisp.
 Strength and action of muscles of mastication areStrength and action of muscles of mastication are
tested by asking the person to clench the teeth andtested by asking the person to clench the teeth and
open the jaw against resistanceopen the jaw against resistance
 Abducent nerveAbducent nerve::
 Note the ability to move each eye outward beyondNote the ability to move each eye outward beyond
the midlinethe midline

44.  Facial nerve:Facial nerve:
 The action of muscles of face is tested by askingThe action of muscles of face is tested by asking
the person to smile, to open the mouth, to showthe person to smile, to open the mouth, to show
the teeth, and to close the eyes tightly.the teeth, and to close the eyes tightly.
 Taste sensations from anterior 2/3 tongue isTaste sensations from anterior 2/3 tongue is
tested using substances that are sweet, sour,tested using substances that are sweet, sour,
salty and bittersalty and bitter
 Vestibulocochlear nerveVestibulocochlear nerve::
 Hearing is tested with a tuning fork.Hearing is tested with a tuning fork.
 Balance is tested by asking the person to walkBalance is tested by asking the person to walk
on a straight line.on a straight line.

45.  GlossopharyngealGlossopharyngeal & Vagus& Vagus nerves:nerves:
 (cranial part of Accessory nerve) :(cranial part of Accessory nerve) :
 The person is asked to swallow.The person is asked to swallow.
 The person is asked to say ‘ah-h-h’ to check theThe person is asked to say ‘ah-h-h’ to check the
movements of palate and uvula.movements of palate and uvula.
 The ‘gag reflex’ is tested by touching the back ofThe ‘gag reflex’ is tested by touching the back of
the throat by the tongue depressor.the throat by the tongue depressor.
 The person is asked to speak to check the voice forThe person is asked to speak to check the voice for
hoarsness.hoarsness.

46.  Spinal part of AccessorySpinal part of Accessory nerve:nerve:
 The person is asked to turn the headThe person is asked to turn the head
and to shrug the shoulders againstand to shrug the shoulders against
resistance provided by the examinerresistance provided by the examiner
 HypoglossalHypoglossal nerve:nerve:
 The person is asked to stick out theThe person is asked to stick out the
tongue, to observe the deviation totongue, to observe the deviation to
one side or the otherone side or the other