Cranial Nerves

CRANIAL NERVESCRANIAL NERVES

ACHMAD AMINUDDINACHMAD AMINUDDIN

OLFATORY NERVE ( CN I )OLFATORY NERVE ( CN I ) CONCERNED WITH THE SPECIAL SENSE OF CONCERNED WITH THE SPECIAL SENSE OF

SMELL.SMELL. THE OLFACTORY RECEPTOR NEURON ARE THE OLFACTORY RECEPTOR NEURON ARE

IN THE OLFACTORY EPITHELIUM IN THE IN THE OLFACTORY EPITHELIUM IN THE ROOF OF THE NASAL CAVITY.ROOF OF THE NASAL CAVITY.

THE CENTRAL PROCESSES OF THE THE CENTRAL PROCESSES OF THE OLFACTORY RECEPTOR NEURONS ASCEND OLFACTORY RECEPTOR NEURONS ASCEND THROUGH FORAMINA IN THE CRIBRIFORM THROUGH FORAMINA IN THE CRIBRIFORM PLATE OF THE ETHMOID TO REACH THE PLATE OF THE ETHMOID TO REACH THE OLFACTORY BULB IN THE ANTERIOR OLFACTORY BULB IN THE ANTERIOR CRANIAL FOSSACRANIAL FOSSA

OLFACTORY NERVE ( CN I )OLFACTORY NERVE ( CN I ) THESE NERVES SYNAPSE ON NEURONS IN THESE NERVES SYNAPSE ON NEURONS IN

THE BULBS, AND THE PROCESSES OF THE BULBS, AND THE PROCESSES OF THESE NEURONS FOLLOW THE OLFACTORY THESE NEURONS FOLLOW THE OLFACTORY TRACT TO THE PRIMARY AND ASSOCIATED TRACT TO THE PRIMARY AND ASSOCIATED AREAS OF THE CEREBRAL CORTEX.AREAS OF THE CEREBRAL CORTEX.

FRACTURE OF THE CRANIAL BASE CAN FRACTURE OF THE CRANIAL BASE CAN INJURE THE OLFACTORY NERVE FIBERS, INJURE THE OLFACTORY NERVE FIBERS, RESULTING IN ANOSMIA, TEARING OF THE RESULTING IN ANOSMIA, TEARING OF THE MENINGES, AND/OR CEREBROSPINAL FLUID MENINGES, AND/OR CEREBROSPINAL FLUID RINORRHEA.RINORRHEA.

THE OLFACTORY PATHWAYTHE OLFACTORY PATHWAY Olfactory tractOlfactory tract ** The lateral olfactory stria, project to the The lateral olfactory stria, project to the primary olfactory area, located at the primary olfactory area, located at the inferior and medial surface of the inferior and medial surface of the temoral lobe, is where conscious aware temoral lobe, is where conscious aware ness of smell begins.ness of smell begins. ** The medial olfactory stria, project to The medial olfactory stria, project to limbic system and hypothalamus ; these limbic system and hypothalamus ; these connections account for our emotional connections account for our emotional

and and memory-evoked responses to odor.memory-evoked responses to odor.

THE OLFACTORY PATHWAYTHE OLFACTORY PATHWAYFrom the primary olfactory area , From the primary olfactory area ,

pathway also extend to the frontal pathway also extend to the frontal lobe , both directly and indirectly via lobe , both directly and indirectly via the thalamus . An important region for the thalamus . An important region for odor identification and discrimination odor identification and discrimination is the orbitofrontal area ( area 11 ).is the orbitofrontal area ( area 11 ).

People who suffer damage in this area People who suffer damage in this area have difficulty identifying different have difficulty identifying different odor.odor.

OPTIC NERVE ( II )OPTIC NERVE ( II ) THE OPTIC NERVES HAVE SENSORY FIBERS THE OPTIC NERVES HAVE SENSORY FIBERS

CONCERNED WITH THE SPECIAL ENSE OF VISION.CONCERNED WITH THE SPECIAL ENSE OF VISION. THE NERVE FIBERS ARISE FROM GANGLION CELL IN THE NERVE FIBERS ARISE FROM GANGLION CELL IN

THE RETINA.THE RETINA. THEY EXIT THE ORBITTHEY EXIT THE ORBIT VIA THE OPTIC CANALS.VIA THE OPTIC CANALS. FIBERS FROM THE NASAL HALF OF THE RETINA FIBERS FROM THE NASAL HALF OF THE RETINA

CROSS TO THE CONTRALATERAL SIDE AT THE OPTIC CROSS TO THE CONTRALATERAL SIDE AT THE OPTIC CHIASM.CHIASM.

FIBERS THE PASS VIA THE OPTIC TRACT TO THE FIBERS THE PASS VIA THE OPTIC TRACT TO THE GENICULATE BODIES OF THE THALAMUS, WHERE GENICULATE BODIES OF THE THALAMUS, WHERE THEY SYNAPSE ON NEURONS WHOSE PROCESSES THEY SYNAPSE ON NEURONS WHOSE PROCESSES FROM THE OPTIC RADIATION TO PRIMARY VISUAL FROM THE OPTIC RADIATION TO PRIMARY VISUAL CORTEX OF THE OCCIPITAL LOBE. CORTEX OF THE OCCIPITAL LOBE.

fig 17.15 594 tortorafig 17.15 594 tortora a , ba , b

fig 17.15 tortora c , dfig 17.15 tortora c , d

AXON COLLATERALS AXON COLLATERALS To the midbrain, they participate in To the midbrain, they participate in

neural circuits that govern constriction pf neural circuits that govern constriction pf the pupil in response to light and the pupil in response to light and coordination of head and eye coordination of head and eye movements.movements.

To the suprachiasmatic nucleus of the To the suprachiasmatic nucleus of the hypothalamus, which establishes patterns hypothalamus, which establishes patterns of sleep and other activities that occur on of sleep and other activities that occur on a circadian or daily schedule in response a circadian or daily schedule in response to intervals of light and darkness.to intervals of light and darkness.

VISUAL FIELD DEFECTSVISUAL FIELD DEFECTS

BLINDNESSBLINDNESS Color blindness, an inherited inability to Color blindness, an inherited inability to

distinguish between cetain color, result distinguish between cetain color, result from the absence or deficiency of one of from the absence or deficiency of one of the three type of conus.the three type of conus.

The most common type is red-green color The most common type is red-green color blindness.blindness.

Night blindness or nyctalopia, result from Night blindness or nyctalopia, result from prolonged vitamin A deficiency and the prolonged vitamin A deficiency and the resulting below normal amount of resulting below normal amount of rhodopsinrhodopsin

OCULOMOTOR NERVE (CN III)OCULOMOTOR NERVE (CN III)Function: Somatic motor ( G.S.E. )Function: Somatic motor ( G.S.E. ) Visceral motor ( g.v.e – parasy )Visceral motor ( g.v.e – parasy )Nuclei:Nuclei: The somatic motor nucleus in the midbrnThe somatic motor nucleus in the midbrn The visceral motor (parasympathetic) The visceral motor (parasympathetic) accessory (Edinger-Westphal) nucleusaccessory (Edinger-Westphal) nucleus

OCULOMOTOR NERVE ( III )OCULOMOTOR NERVE ( III ) THE OCULOMOTOR NERVES SENDTHE OCULOMOTOR NERVES SEND SOMATIC MOTOR SOMATIC MOTOR

FIBERS TO ALL EXTRA OCULAR MUSCLES, EXCEP FIBERS TO ALL EXTRA OCULAR MUSCLES, EXCEP THE SUPERIOR OBLIQUE AND LATERAL RECTUS.THE SUPERIOR OBLIQUE AND LATERAL RECTUS.

THEY ALSO SEND PRESYNAPTIC PARA THEY ALSO SEND PRESYNAPTIC PARA SYMPATHETIC FIBERS TO THE CILIARY GANGLION SYMPATHETIC FIBERS TO THE CILIARY GANGLION FOR INNERVATION OF THE CILIARY BODY AND FOR INNERVATION OF THE CILIARY BODY AND SPHINCTER PUPILLAESPHINCTER PUPILLAE

THESE NERVES ORIGINATE FROM BRAIN STEMTHESE NERVES ORIGINATE FROM BRAIN STEM EMERGING MEDIAL TO THE CEREBRAL PEDUNCLES, EMERGING MEDIAL TO THE CEREBRAL PEDUNCLES, AND RUN IN THE LAERAL WALL OF THE AND RUN IN THE LAERAL WALL OF THE CAVERNOUS SINUS.CAVERNOUS SINUS.

THEYTHEY ENTER THE ORBIT THROUGH THE SUPERIOR ENTER THE ORBIT THROUGH THE SUPERIOR ORBITAL FISSURE AND DEVIDE INTO SUPERIOR ORBITAL FISSURE AND DEVIDE INTO SUPERIOR AND INFERIOR BRANCHESAND INFERIOR BRANCHES

fig 14.20 503 torfig 14.20 503 tor

INJURY TO THE CN IIIINJURY TO THE CN IIITypes / sites of lesionTypes / sites of lesion Pressure from herniating uncus on Pressure from herniating uncus on

nerve; nerve; fracture involving cavernous sinus; fracture involving cavernous sinus; aneurysm.aneurysm.Abnormal findingsAbnormal findings Dilated pupil; ptosis; eye turns down and Dilated pupil; ptosis; eye turns down and out; pupillary reflex on the side of the out; pupillary reflex on the side of the lesion will be lost.lesion will be lost.

COMPRESSION OF THE CN IIICOMPRESSION OF THE CN III Rapidly increasing intracranial pressure Rapidly increasing intracranial pressure ( extradural hematom ) often compress ( extradural hematom ) often compress

CN III against the crest of the petrous part CN III against the crest of the petrous part of the temporal bone.of the temporal bone.

ResultResult - Pupil dilates progressively on the injured - Pupil dilates progressively on the injured side.side. - Ipsilateral slowness of the pupillary - Ipsilateral slowness of the pupillary response to lightresponse to light

TROCHLEAR NERVE (CN III)TROCHLEAR NERVE (CN III)FunctionsFunctions Somatic motor (general somatic Somatic motor (general somatic

efferent) efferent) and proprioceptive to superior oblique and proprioceptive to superior oblique

m.m.NucleusNucleus The nucleus of the trochlear nerve is The nucleus of the trochlear nerve is

located in the midbrain, immediately located in the midbrain, immediately caudal to the oculomotor nucleus.caudal to the oculomotor nucleus.

TROCHLEAR NERVE ( IV )TROCHLEAR NERVE ( IV ) THE TROCHLEAR NERVE SUPPLY SOMATIC MOTOR FIBERS TO THE TROCHLEAR NERVE SUPPLY SOMATIC MOTOR FIBERS TO

THE SUPERIOR OBLIQUE MUSCLES AND SENDS THE SUPERIOR OBLIQUE MUSCLES AND SENDS PROPRIOCEPTIVR FIBERS TO THIS MUSCLE, WHICH ABDUCTS, PROPRIOCEPTIVR FIBERS TO THIS MUSCLE, WHICH ABDUCTS, DEPRESSESDEPRESSES AND MEDIALLY ROTATES THE EYEBALL.AND MEDIALLY ROTATES THE EYEBALL.

THE NERVES EMERGE FROM THE POSTERIOR ASPECT OF THE THE NERVES EMERGE FROM THE POSTERIOR ASPECT OF THE BRAIN STEM.BRAIN STEM.

THEY RUN ALONG INTRA CRANIAL COURSE , PASSING THEY RUN ALONG INTRA CRANIAL COURSE , PASSING AROUND THE BRAIN STEM TO ENTER THE DURAMATER IN THE AROUND THE BRAIN STEM TO ENTER THE DURAMATER IN THE FREE EDGE OF THE CEREBELLAR TENTORIUM CLOSE TO THE FREE EDGE OF THE CEREBELLAR TENTORIUM CLOSE TO THE POSTERIOR CLINOID PROCESS.POSTERIOR CLINOID PROCESS.

THE RUN IN THE LATERAL WALL OF THE CAVERNOUS SINUS, THE RUN IN THE LATERAL WALL OF THE CAVERNOUS SINUS, ENTERING THE ORBIT VIA THE SUPERIOR ORBIT FISSURES.ENTERING THE ORBIT VIA THE SUPERIOR ORBIT FISSURES.

STRETCHING DURING ITS COURSE AROUND THE BRAIN STEM, STRETCHING DURING ITS COURSE AROUND THE BRAIN STEM, OR FRACTURE OF THE ORBIT CAN RESULT IN AN INABILITY TO OR FRACTURE OF THE ORBIT CAN RESULT IN AN INABILITY TO LOOK DOWN WHEN THE EYE BALL IS ADDUCTED.LOOK DOWN WHEN THE EYE BALL IS ADDUCTED.

THE CN IV IS UNIQUETHE CN IV IS UNIQUE It is the smallest.It is the smallest. It is the only nerve to exit from the It is the only nerve to exit from the

dorsal aspect of the brain stem.dorsal aspect of the brain stem. It is the only nerve in which all of the It is the only nerve in which all of the

lower motor neuron axons decussate.lower motor neuron axons decussate. It has the longest intracranial courseIt has the longest intracranial course

CLINICAL CORRELATESCLINICAL CORRELATES Lesions of this nerve or its nucleus cause Lesions of this nerve or its nucleus cause

paralysis of the superior oblique and paralysis of the superior oblique and impair the ability to turn the affected impair the ability to turn the affected eyeball inferomedially.eyeball inferomedially.

The characteristic sign of trochlear nerve The characteristic sign of trochlear nerve injury is diplopia when looking down.injury is diplopia when looking down.

The person can compensate for the The person can compensate for the diplopia by inclining the head anteriorly diplopia by inclining the head anteriorly and laterally toward the side of the normal and laterally toward the side of the normal eye.eye.

TRIGEMINAL NERVE (CN V)TRIGEMINAL NERVE (CN V) Funcions : General somatic afferent Funcions : General somatic afferent Nuclei: there are 4 trigeminal nuclei, one Nuclei: there are 4 trigeminal nuclei, one

motor and three sensory.motor and three sensory. Trigeminal ganglionTrigeminal ganglion - Ophthalmic nerve ( CN V 1 )- Ophthalmic nerve ( CN V 1 ) - Maxillary nerve ( CN V 2 )- Maxillary nerve ( CN V 2 ) - Mandibular nerve ( CN V 3 )- Mandibular nerve ( CN V 3 ) The motor root of CN VThe motor root of CN V Four parasympatheic ganglia are Four parasympatheic ganglia are

associated with the divisions of CN V , associated with the divisions of CN V , sensory and motorsensory and motor

TRIGEMINAL NERVE (CN V)TRIGEMINAL NERVE (CN V)CN V is the principal general sensory CN V is the principal general sensory

nerve for the head ( face, teeth, nerve for the head ( face, teeth, mouth, nasal cavity and dura of the mouth, nasal cavity and dura of the cranial cavity.cranial cavity.

Branchial motor to the muscles of Branchial motor to the muscles of mastication. Mylohyoid, anterior belly mastication. Mylohyoid, anterior belly of the digastric, tensor velipalatini and of the digastric, tensor velipalatini and tensor tympani ( 1st branchial arch )tensor tympani ( 1st branchial arch )

OPHTHALMIC NERVEW (CN OPHTHALMIC NERVEW (CN V1)V1)

The sensoy fibers are distributed to The sensoy fibers are distributed to skin and mucous membrane and skin and mucous membrane and conjunctiva of the front of the head conjunctiva of the front of the head and nose.and nose.

Testing CN V1 : checking the corneal Testing CN V1 : checking the corneal reflex , with a wisp of cotton to the reflex , with a wisp of cotton to the cornea will evoke a reflexive blink if cornea will evoke a reflexive blink if the nerve is functional.the nerve is functional.

MAXILLARY NERVE (CN V2)MAXILLARY NERVE (CN V2)CN V2 innrvates derivates of the maxillary CN V2 innrvates derivates of the maxillary

prominence of the first pharyngeal arch.prominence of the first pharyngeal arch.Exiting the cranial cavity via the foramen Exiting the cranial cavity via the foramen

rotundum.rotundum.Distributed to skin and mucous membtane Distributed to skin and mucous membtane

associated with the upper jaw.associated with the upper jaw.The pterygopalatine ganglion is The pterygopalatine ganglion is

associated with CN V2, involved in associated with CN V2, involved in innervating the lacrimal and mucus innervating the lacrimal and mucus glands.glands.

MANDIBUALR NERVE (CN V3)MANDIBUALR NERVE (CN V3) CN V3 innervates derivates of the CN V3 innervates derivates of the

mandibular prominence of the 1st mandibular prominence of the 1st pharyngeal arch.pharyngeal arch.

CN V3 is the only division of the CN V to CN V3 is the only division of the CN V to convey motor to the striated muscle derived convey motor to the striated muscle derived from mandibular prominence mesoderm, from mandibular prominence mesoderm, primarily the muscle of mastication.primarily the muscle of mastication.

The otic and submandibular ganglia are The otic and submandibular ganglia are associated with CN V3, both are concerned associated with CN V3, both are concerned with the innervation of salivary glands with the innervation of salivary glands

INJURY TO THE ENTIRE INJURY TO THE ENTIRE TRIGEMINAL NERVETRIGEMINAL NERVE

Paralysis of the muscle of mastication Paralysis of the muscle of mastication with deviation of the mandible toward with deviation of the mandible toward the side of the lesion.the side of the lesion.

Los of the ability to appreciate soft Los of the ability to appreciate soft tactile , thermal or painful sensations tactile , thermal or painful sensations in the face .in the face .

Los of corneal reflex and the sneezing Los of corneal reflex and the sneezing reflexreflex

TRIGEMINAL NEURALGIATRIGEMINAL NEURALGIATN is a sensory disorder of the sensory TN is a sensory disorder of the sensory

root of CN V that occur most often in root of CN V that occur most often in middle-aged and elderly person.middle-aged and elderly person.

Characterized by sudden attacks of Characterized by sudden attacks of exruciating, lightening-like jabs of facial exruciating, lightening-like jabs of facial pain.pain.

CN V2 is most frequently involved, then CN V2 is most frequently involved, then CN V3, and least frequiently CN V1CN V3, and least frequiently CN V1

THE CAUSE OF THE T.N. Is THE CAUSE OF THE T.N. Is unknownunknown

Anomalous blood vessel that Anomalous blood vessel that compresses the nerve.compresses the nerve.

Pathological process in the trigeminal Pathological process in the trigeminal ganglion and in the nucleus of the ganglion and in the nucleus of the spinal tractspinal tract

ABDUCENT NERVE ( CN VI )ABDUCENT NERVE ( CN VI ) THE ABDUCENT NERVES SUPPLY SOMATIC MOTOR THE ABDUCENT NERVES SUPPLY SOMATIC MOTOR

FIBERS TO THE LATERAL RECTUS MUSCLESFIBERS TO THE LATERAL RECTUS MUSCLES OF OF THE EYE BALL AND PROPRIOCEPTIVE FIBERS TO THE EYE BALL AND PROPRIOCEPTIVE FIBERS TO THESE MUSCLES.THESE MUSCLES.

THE NERVES ORIGINATE FROM THE PONS, PIERCE THE NERVES ORIGINATE FROM THE PONS, PIERCE THE DURA ON THE CLIVIS TRAVERSE THE THE DURA ON THE CLIVIS TRAVERSE THE CAVERNOUS SINUS AND SUPERIOR ORBITAL CAVERNOUS SINUS AND SUPERIOR ORBITAL FISSURES, AND ENTER THE ORBIT.FISSURES, AND ENTER THE ORBIT.

INJURY TO THE BASE OF THE BRAIN OR A INJURY TO THE BASE OF THE BRAIN OR A FRACTURE OF THE CRANIAL BASE INVOLVING THE FRACTURE OF THE CRANIAL BASE INVOLVING THE CAVERNOUS SINUS OR ORBIT CAN RESULT IN CAVERNOUS SINUS OR ORBIT CAN RESULT IN INABILITY TO MOVE THE EYE LATERALLY, AND INABILITY TO MOVE THE EYE LATERALLY, AND DIPLOPIA OCCURS ON LATERAL GAZEDIPLOPIA OCCURS ON LATERAL GAZE

FACIAL NERVEFACIAL NERVEFUNCTIONFUNCTION SENSORY ; - special vSENSORY ; - special viisceral afferent.sceral afferent. - general somatic afferent.- general somatic afferent. MOTOR ; - special visceral afferent.MOTOR ; - special visceral afferent. - general visceral efferent, - general visceral efferent, ( parasympathetic ).( parasympathetic ). PROPRIOCEPTIVE.PROPRIOCEPTIVE.

FUNCTIONSFUNCTIONS BRANCHIAL MOTOR (S.V.E.)BRANCHIAL MOTOR (S.V.E.) Stapedius, stylohyoid, posterior belly of Stapedius, stylohyoid, posterior belly of digastric muscles.digastric muscles. Facial expression ; buccinator, platysma Facial expression ; buccinator, platysma and occipitalis musclesand occipitalis muscles VISCERAL MOTOR (G.V.E.)VISCERAL MOTOR (G.V.E.) Stimulation of the lacrimal, submandibula Stimulation of the lacrimal, submandibula and sublingual glands.and sublingual glands. The mucous membrane of the nose, and The mucous membrane of the nose, and

hard hard and soft palatesand soft palates

FUNCTIONSFUNCTIONS GENERAL SENSORY (G.S.A.)GENERAL SENSORY (G.S.A.) The skin of the concha of the auricle, a The skin of the concha of the auricle, a small area of skin behind the ear, and small area of skin behind the ear, and possibly to supplement V3, which supplies possibly to supplement V3, which supplies the wall ofthe acousti cmeatus and external the wall ofthe acousti cmeatus and external

tympanic membranetympanic membrane SPECIAL SENSORY (S.A.)SPECIAL SENSORY (S.A.) For taste from the anterior two-thirds of For taste from the anterior two-thirds of the tongue and the hard and soft palates.the tongue and the hard and soft palates.

NUCLEINUCLEIMOTOR ; in the ventrolataral part of the MOTOR ; in the ventrolataral part of the pons ( branchiomotor ).pons ( branchiomotor ).SENSORY ; in the geniculate ganglion.SENSORY ; in the geniculate ganglion. - taste ; in the nuclei of the solitary - taste ; in the nuclei of the solitary

trac trac in the medulla.in the medulla. - general sensation ; - general sensation ; in the spinal nucleus of the in the spinal nucleus of the trigeminal nerve.trigeminal nerve.

THE FACIAL NERVETHE FACIAL NERVEFrom the junction of the pons and From the junction of the pons and

medullamedullaTHE LARGE MOTOR ROOTTHE LARGE MOTOR ROOT innervates the muscles of facial innervates the muscles of facial expresion.expresion.THE SMALLER INERMEDIATE NERVETHE SMALLER INERMEDIATE NERVE carries taste, parasympathetic, carries taste, parasympathetic, somatic sensory fibers.somatic sensory fibers.

THE FACIAL NERVETHE FACIAL NERVE IN THE TEMPORAL BONE, GIVE RISE TO ;IN THE TEMPORAL BONE, GIVE RISE TO ; - greater petrosal n.- greater petrosal n. - nerve to the stapedius.- nerve to the stapedius. - chorda tympani n.- chorda tympani n. EMERGES FROM THE STYLOMSTOID EMERGES FROM THE STYLOMSTOID FORAMEN, GIVE OFF ;FORAMEN, GIVE OFF ; - posterior auricular branch.- posterior auricular branch. - the parotic plexus, give rise 5 termi-- the parotic plexus, give rise 5 termi- nal motor : temporal, zygomatic, nal motor : temporal, zygomatic,

buccal,buccal, marginal mandibular and cervical.marginal mandibular and cervical.

FACIAL NERVEFACIAL NERVEBRANCHIAL MOTOR,BRANCHIAL MOTOR, SUPPLIES : SUPPLIES : - STRIATED MUSCLES OF FACIAL - STRIATED MUSCLES OF FACIAL EXPRESSION AND AURICULAR EXPRESSION AND AURICULAR

MUSCLE.MUSCLE. - THE POSTERIOR BELLIES OF THE DI- - THE POSTERIOR BELLIES OF THE DI- GASTRIC MUSCLE.GASTRIC MUSCLE. - STYLOID M.- STYLOID M. - STAPEDIUS M.- STAPEDIUS M.

THE FACIAL NERVETHE FACIAL NERVE PRESYNAPTIC PARASYMPATHETIC ( GVE )PRESYNAPTIC PARASYMPATHETIC ( GVE ) - pterygopalatine ganglion.- pterygopalatine ganglion. - the lacrimal mucous glands.- the lacrimal mucous glands. - submandibular ganglion,- submandibular ganglion, - sublingual glands.- sublingual glands. - submandibular glands.- submandibular glands. GENERAL SOMATIC GENERAL SOMATIC - small area of the skin of aurical concha- small area of the skin of aurical concha TASTE ( SPECIAL SENSORY )TASTE ( SPECIAL SENSORY ) - chordatympani joint the lingual n to convey - chordatympani joint the lingual n to convey taste sensation from the anterior twothird of taste sensation from the anterior twothird of the tongue and soft palate.the tongue and soft palate.

VESTIBULOCOCHLEAR NERVEVESTIBULOCOCHLEAR NERVE FUNCTIONSFUNCTIONS special sensory ( special somatic special sensory ( special somatic afferent ) of hearing and equilibrium.afferent ) of hearing and equilibrium. NUCLEINUCLEI - vestibular nuclei are located at the - vestibular nuclei are located at the junction of the pons and medulla in junction of the pons and medulla in the lateral part of the floor of 4the lateral part of the floor of 4thth ventricle.ventricle. - cochlear nuclei are in the medulla.- cochlear nuclei are in the medulla.

THE VESTIBULOCOCHLEAR THE VESTIBULOCOCHLEAR NERVENERVE

ENTER THE INTERNAL ACOUSTIC ENTER THE INTERNAL ACOUSTIC MEATUS, SEPARATES INTO ;MEATUS, SEPARATES INTO ; - THE VESTIBULAR NERVE- THE VESTIBULAR NERVE - vestibular ganglion- vestibular ganglion - macula of the uticle and - macula of the uticle and

saculesacule - ampula of the semicircular duc- ampula of the semicircular duc - THE COCHLEAR NERVE- THE COCHLEAR NERVE - spiral ganglion- spiral ganglion

COCHLEAR COMPONENTCOCHLEAR COMPONENT Sensory receptor, the hair cells in the cochlear duct.Sensory receptor, the hair cells in the cochlear duct. Primary sensory neuron, the (spiral) organ of corti, Primary sensory neuron, the (spiral) organ of corti,

are located around the modiolus (center) of the are located around the modiolus (center) of the cochlea, collectively consti- tute the cochlear cochlea, collectively consti- tute the cochlear (spiral) ganglion. The central processes of these (spiral) ganglion. The central processes of these neuron form neuron form

The auditory component of the vestibulo- cochlear The auditory component of the vestibulo- cochlear nerve. These axon leave the base of the cochlea, nerve. These axon leave the base of the cochlea, joint with the vestibular fibers, enter the posterior joint with the vestibular fibers, enter the posterior cranial fossa via the internal acustic meatus.The cranial fossa via the internal acustic meatus.The primary sensory neurons terminate in the dorsal primary sensory neurons terminate in the dorsal (high frequencies) and ventral (low frequencies) (high frequencies) and ventral (low frequencies) cochlear nuclei at the junction of the pons and cochlear nuclei at the junction of the pons and medullamedulla

SPIRAL ORGAN ( ORGAN OF SPIRAL ORGAN ( ORGAN OF CORTI)CORTI)

fig 17.19 c,d 600fig 17.19 c,d 600

fig 20.3 clin n 231fig 20.3 clin n 231

VESTIBULAR COMPONENTVESTIBULAR COMPONENTThe vestibular apparatus consist of the The vestibular apparatus consist of the

saccule and utricle, and three saccule and utricle, and three semicircular canal.semicircular canal.

The main function of the saccule and The main function of the saccule and utricle is to detect the position of the utricle is to detect the position of the head relative to gravity ( static head relative to gravity ( static labyrinth ).labyrinth ).

Both saccule and utricle have a Both saccule and utricle have a sensory receptors called the maculasensory receptors called the macula

VESTIBULAR COMPONENTVESTIBULAR COMPONENTThe three semicircular canal sit at the The three semicircular canal sit at the

right angles to each other in the three right angles to each other in the three planes of the body.planes of the body.

The canal perceive angular movement The canal perceive angular movement of the head in space ( kinetic of the head in space ( kinetic labyrinth ).labyrinth ).

The canals are filled with endolymph.The canals are filled with endolymph.Each canal has an ampula that contains Each canal has an ampula that contains

a patch of hair cellsa patch of hair cells

fig 17.21 tor 604fig 17.21 tor 604

fig 17.22 torfig 17.22 tor

EQUILIBRIUM PATHWAYSEQUILIBRIUM PATHWAYS Most of the vestibular branch axon enter Most of the vestibular branch axon enter

the medulla and pons and terminate in the medulla and pons and terminate in several vesibular nuclei.several vesibular nuclei.

The remaining axons enter the cerebellum The remaining axons enter the cerebellum through the inferior cerebellar peduncle.through the inferior cerebellar peduncle.

Bidiretional pathways connect the Bidiretional pathways connect the vestibular nuclei and cerebellum.vestibular nuclei and cerebellum.

Axon from allthe vestibuar nuclei extend Axon from allthe vestibuar nuclei extend to the nuclei of cranial nerves that control to the nuclei of cranial nerves that control eye movements, CN III, CN IV nd CN VI. the eye movements, CN III, CN IV nd CN VI. the axon extend to CN XI, which help control axon extend to CN XI, which help control head and neck movementshead and neck movements

EQUILIBRIUM PATHWAYSEQUILIBRIUM PATHWAYS Axon from the lateral vestibular nucleus form the Axon from the lateral vestibular nucleus form the

vestibulospinal tract.vestibulospinal tract. Various pathways between the vestibular nuclei, Various pathways between the vestibular nuclei,

cerebellum and cerebrum, enable the cerebellum to cerebellum and cerebrum, enable the cerebellum to play a role in maintaining equilibrium.play a role in maintaining equilibrium.

The cerebellum continuously receives updated The cerebellum continuously receives updated sensory information from the utricle and saccule, sensory information from the utricle and saccule, and makes corrective adjustments.and makes corrective adjustments.

In response to input from the utricle, saccule and In response to input from the utricle, saccule and semicircular ducts, the cerebellum continuously semicircular ducts, the cerebellum continuously sends nerve impulses to the motor area of the sends nerve impulses to the motor area of the cerebrum.cerebrum.

Correction of signals from the motor cortex to Correction of signals from the motor cortex to specific skeletal muscles to maintain equilibrium.specific skeletal muscles to maintain equilibrium.

GLOSSOPHARYNGEAL NERVEGLOSSOPHARYNGEAL NERVE FUNCTION FUNCTION SOMATIC – general somatic afferent.SOMATIC – general somatic afferent. -- special visceral afferent.-- special visceral afferent. -- general visceral afferent.-- general visceral afferent. MOTOR - special visceral efferent.MOTOR - special visceral efferent. - general visceral efferent - general visceral efferent ( parasympathetic ) to deriv ( parasympathetic ) to deriv of the 3of the 3rdrd pharyngeal arch. pharyngeal arch. NUCLEINUCLEI 4 nuclei in the medulla, two motor and 4 nuclei in the medulla, two motor and

two two sensorysensory

COMPONENTS OF CN IXCOMPONENTS OF CN IXBranchial motor (SVE)Branchial motor (SVE) To the striated muscel, the stylopharyngsTo the striated muscel, the stylopharyngsVisceral motor (GVE)Visceral motor (GVE) To the otic ganglion, which sends fibers toTo the otic ganglion, which sends fibers to stimulate the parotid gland.stimulate the parotid gland.Visceral sensory (GVA)Visceral sensory (GVA) Carries sensation (subconscious) from the Carries sensation (subconscious) from the carotid body and from the carotid sinuscarotid body and from the carotid sinus

COMPONENTS OF CN IXCOMPONENTS OF CN IXGeneral sensory (GSA)General sensory (GSA) Provides general sensation from the Provides general sensation from the posterior one-third of the tongue, the posterior one-third of the tongue, the

skin skin of the external ear, and the internal of the external ear, and the internal surface of the tympanic membane surface of the tympanic membane Special sensory (SA)Special sensory (SA) For taste from the posterior one-third of For taste from the posterior one-third of the tongue.the tongue.

GLOSSOPHARYNGEAL NERVEGLOSSOPHARYNGEAL NERVE FROM THE LATERAL ASPECT OF THE MEDULLA FROM THE LATERAL ASPECT OF THE MEDULLA

THEN ENTER THE JUGULAR FORAMEN ARE THEN ENTER THE JUGULAR FORAMEN ARE - SUPERIOR GANGLION.- SUPERIOR GANGLION. - INFERIOR GANGLION ( SENSORY )- INFERIOR GANGLION ( SENSORY ) WHICH CONTAIN THE NERVE CELL BODIES WHICH CONTAIN THE NERVE CELL BODIES

THAT MEDIATE GENERAL, VISCERAL, AND THAT MEDIATE GENERAL, VISCERAL, AND SPECIAL SENSATIONSPECIAL SENSATION

◊◊ The tympanic nerve is given off before the The tympanic nerve is given off before the main trunk exits the skull through the jugular main trunk exits the skull through the jugular foramenforamen

fig 9.11 1149fig 9.11 1149

GLOSSOPHARYNGEAL NERVEGLOSSOPHARYNGEAL NERVECarotid nerves from the carotid body Carotid nerves from the carotid body

and the sinus join the inferior and the sinus join the inferior ganglion, as do the lingual and ganglion, as do the lingual and pharyngeal branches, which bring pharyngeal branches, which bring sensation (general and special) from sensation (general and special) from the tongue and pharynx.the tongue and pharynx.

The branchial motor fibers supply The branchial motor fibers supply one muscel, the styliopharyngeusone muscel, the styliopharyngeus

BRANCHIAL MOTORBRANCHIAL MOTOR Impulse from cortex cerebri descend along Impulse from cortex cerebri descend along

the corticobulbar fibers through the the corticobulbar fibers through the internal capsule and through the basis internal capsule and through the basis pedunculi to synapse bilaterally on the pedunculi to synapse bilaterally on the lower motor neurons in the rostral part of lower motor neurons in the rostral part of the nucleus ambiguus.the nucleus ambiguus.

The lower motor neuron axons join the The lower motor neuron axons join the other modalities of CN IX.other modalities of CN IX.

The CN IX emerge in the groove between The CN IX emerge in the groove between olive and the inferior cerebellar peduncle.olive and the inferior cerebellar peduncle.

BRANCHIAL MOTORBRANCHIAL MOTOR The nerve passes laterally in the posterior The nerve passes laterally in the posterior

cranial fossa to exit through the jugular cranial fossa to exit through the jugular foramen anterior to the vagus and the foramen anterior to the vagus and the accessory nerves.accessory nerves.

From the jugular foramen branchial motor of From the jugular foramen branchial motor of the CN IX descend in the neck deep to the the CN IX descend in the neck deep to the sttyloid process and then curve forward sttyloid process and then curve forward around the posterior border of around the posterior border of stylopharyngeus muscle where the nerve stylopharyngeus muscle where the nerve supplies the muscle.supplies the muscle.

The mucle elevates the pharynx during The mucle elevates the pharynx during swallowing speech.swallowing speech.

VISCERAL MOTORVISCERAL MOTOR Preganglionic fibers of the parasympathetic Preganglionic fibers of the parasympathetic

motor are located in the INFERIOR motor are located in the INFERIOR SALIVATORY NUCLEUS in the medulla. Axon SALIVATORY NUCLEUS in the medulla. Axon from these nucleus join the other components from these nucleus join the other components of of cranial nerve IX in the medulla and exit of of cranial nerve IX in the medulla and exit with them through the jugular foramen.with them through the jugular foramen.

The tympanic nerve leaves the inferior The tympanic nerve leaves the inferior ganglion to ascend through inferior tympanic ganglion to ascend through inferior tympanic canaliulus. It reaches the tympanic cavity canaliulus. It reaches the tympanic cavity where it forms a plexus on the surface of the where it forms a plexus on the surface of the promontory of the middle ear cavitypromontory of the middle ear cavity

VISCERAL MOTORVISCERAL MOTOR From this plexus branches supply sensation to From this plexus branches supply sensation to

the mucous membrane of the cavity, auditory the mucous membrane of the cavity, auditory tube and mastoid air cells and the visceral tube and mastoid air cells and the visceral motor fibers form the LESSER PETROSAL motor fibers form the LESSER PETROSAL NERVE.NERVE.

This nerve travel back into the middle cranial This nerve travel back into the middle cranial fossa, passes forward to descend through the fossa, passes forward to descend through the oval foramen to synape in the OTIC ganglion.oval foramen to synape in the OTIC ganglion.

From this ganglion post ganglionic fibers join From this ganglion post ganglionic fibers join the AURICULOTEMPORAL nerve (branch of V3) the AURICULOTEMPORAL nerve (branch of V3) to supply secretomotor fibers to the parotid to supply secretomotor fibers to the parotid glandgland

fig 9.10 A 1148fig 9.10 A 1148

VISCERAL SENSORY VISCERAL SENSORY Chemoreceptor from the carotid body monitor Chemoreceptor from the carotid body monitor

oxygen tension in circulating blood and oxygen tension in circulating blood and baroreceptor (strech receptor) in the carotid sinus baroreceptor (strech receptor) in the carotid sinus monitor arterial blood pressure.monitor arterial blood pressure.

These sensation are relayed in the carotid nerve These sensation are relayed in the carotid nerve toward the inferior ganglion.Central processes of toward the inferior ganglion.Central processes of these neurons pass to the tractus solitarius to these neurons pass to the tractus solitarius to descend to the more caudal part of the nucleus descend to the more caudal part of the nucleus solitarius.solitarius.

From this nucleus connections are made with the From this nucleus connections are made with the reticular formation and the hypothalamus for the reticular formation and the hypothalamus for the appropriate reflex responses for the control of appropriate reflex responses for the control of respiration, blood pressure and cardiac out put.respiration, blood pressure and cardiac out put.

fig 9.10 Bfig 9.10 B

GENERAL SENSORYGENERAL SENSORY Axon for pain and temperature from the skin Axon for pain and temperature from the skin

of part of the external ear, the inner surface of of part of the external ear, the inner surface of the tympanic membrane, the posterior third of the tympanic membrane, the posterior third of the tongue and the upper pharynx have their the tongue and the upper pharynx have their nerve cell bodies in either the SUPERIOR or nerve cell bodies in either the SUPERIOR or INFERIOR GLOSSOPHARYNGEAL GANGLIA.INFERIOR GLOSSOPHARYNGEAL GANGLIA.

The central processes for pain enter the spinal The central processes for pain enter the spinal nucleus of trigeminal nerve.nucleus of trigeminal nerve.

From this nucleus, its axon cross the midline in From this nucleus, its axon cross the midline in the medulla and ascend to the contralateral the medulla and ascend to the contralateral ventral posterior nucleus of the thalmusventral posterior nucleus of the thalmus

Axon of tertiary neuron project to the Axon of tertiary neuron project to the postcentral sensory gyrus.postcentral sensory gyrus.

SPECIAL SENSORYSPECIAL SENSORY Taste sensation from the posterior one-Taste sensation from the posterior one-

third of the tongue including the vallate third of the tongue including the vallate papillae, is carried by special sensory papillae, is carried by special sensory processes towards neurons in the inferior processes towards neurons in the inferior glossopharyngeal ganglion.glossopharyngeal ganglion.

Central processes from these neurons Central processes from these neurons pass through the jugular foramen, enter pass through the jugular foramen, enter the medulla and ascend in the central the medulla and ascend in the central tegmental tract of the brain stem to reach tegmental tract of the brain stem to reach the ipsilateral and contralateral ventral the ipsilateral and contralateral ventral posterior nuclei of thethalami.posterior nuclei of thethalami.

Tertiary neuron project to reach the Tertiary neuron project to reach the primary sensory cortex in the inferior third primary sensory cortex in the inferior third of the postcentral gyrus where the taste is of the postcentral gyrus where the taste is perceived.perceived.

VAGUS NERVE ( CN X )VAGUS NERVE ( CN X ) FUNCTIONSFUNCTIONS Sensory ( general somatic aferent, special Sensory ( general somatic aferent, special visceral afferent, general visceral visceral afferent, general visceral afferent ).afferent ). Motor ; special visceral efferent.Motor ; special visceral efferent. Parasympathethic ; geeral visceral efferenParasympathethic ; geeral visceral efferen• NUCLEINUCLEI Four nuclei of CN X in the medulla, send or Four nuclei of CN X in the medulla, send or

receive fibers via CN IX – two motor and two receive fibers via CN IX – two motor and two sensory.sensory. Three of these nuclei are shared with CN IX.Three of these nuclei are shared with CN IX.

VAGUS NERVEVAGUS NERVE SENSORY from ;SENSORY from ; - inferior pharynx - larynx.- inferior pharynx - larynx. - thoracic organ. - abdominal organs- thoracic organ. - abdominal organs SENSE OF TASTE from ;SENSE OF TASTE from ; - the root of the tongue.- the root of the tongue. - taste buds on the epiglottis.- taste buds on the epiglottis. MOTOR to ;MOTOR to ; - soft palate - pharynx.- soft palate - pharynx. - intrinsic laryngeal muscles ( phonation ).- intrinsic laryngeal muscles ( phonation ). - extrinsic tongue muscle.- extrinsic tongue muscle. - palatoglossus- palatoglossus• Proprioceptive to the muscles listed above.Proprioceptive to the muscles listed above.• Parasympathetic to thoracic and abdominal viscera.Parasympathetic to thoracic and abdominal viscera.

THE VAGUS NERVETHE VAGUS NERVE In the jugular foramen positioned In the jugular foramen positioned

between between CN IX and CN X.CN IX and CN X.• Superior ganglion ; general sensory.Superior ganglion ; general sensory.• Inferior ganglion ; visceral sensory.Inferior ganglion ; visceral sensory.• In the regio of the superior ganglion are In the regio of the superior ganglion are

connection to CN IX and the superior connection to CN IX and the superior cervical ganglion ( sympathetic )cervical ganglion ( sympathetic )

SPINAL ACCESSORY NERVE ( CN SPINAL ACCESSORY NERVE ( CN XI )XI )

Funtions ; motor to Funtions ; motor to sternocleidomastoideusternocleidomastoideu

and trapezius muscles. and trapezius muscles. Nuclei ; nucleus of the accessory nerve.Nuclei ; nucleus of the accessory nerve.From the side of the spinal cord in the From the side of the spinal cord in the

superior five or six cervical segmen.superior five or six cervical segmen.They ascend in the cranial cavity via the They ascend in the cranial cavity via the

foramen magnum and exit through the foramen magnum and exit through the jugular foramina, crossing the lateral jugular foramina, crossing the lateral cervical regioncervical region

HYPOGLOSSAL NERVE (CN HYPOGLOSSAL NERVE (CN XII)XII)

Functions : Motor ( general somatic Functions : Motor ( general somatic efferent ) to the intrinsic and efferent ) to the intrinsic and extrinsic muscles of the tongue – extrinsic muscles of the tongue – styloglossus, hyoglossus, and styloglossus, hyoglossus, and genioglossus.genioglossus.

The hypoglossal nucleus is located in The hypoglossal nucleus is located in the tegmentum of the medullathe tegmentum of the medulla

HYPOGLOSSAL NERVEHYPOGLOSSAL NERVE Arses as a purely motor nerve from the Arses as a purely motor nerve from the

medulla and leaves the cranium through medulla and leaves the cranium through the hypoglossal canal.the hypoglossal canal.

After exiting the cranial cavity, CN XII is After exiting the cranial cavity, CN XII is joined by branches of the cervical plexus joined by branches of the cervical plexus conveying general somatic motor fibers conveying general somatic motor fibers from C1 and C2 spinal nerves and general from C1 and C2 spinal nerves and general somatic sensory fibers from the spinal somatic sensory fibers from the spinal ganglion of C2.ganglion of C2.

CN XII passes inferiorly medial to the angle CN XII passes inferiorly medial to the angle of the mandible and then curves anteriorly of the mandible and then curves anteriorly to enter the tongueto enter the tongue

HYPOGLOSSAL NERVEHYPOGLOSSAL NERVE A meningeal branch, returns to the A meningeal branch, returns to the

cranium through the hypoglossal canal cranium through the hypoglossal canal and innervates the duramater on the floor and innervates the duramater on the floor and posterior wall of the posterior cranial and posterior wall of the posterior cranial fossa.fossa.

The superior root of the ansa cervicalis, The superior root of the ansa cervicalis, suply the infrahyoid muscles suply the infrahyoid muscles (sternohyoid,sternothyroid, and omohyoid(sternohyoid,sternothyroid, and omohyoid

Lingual branches, supply the styloglossus, Lingual branches, supply the styloglossus, hyoglossus, genioglossus and intrinsic hyoglossus, genioglossus and intrinsic muscles of the tongue.muscles of the tongue.

HYPOGLOSSAL NERVE ( CN HYPOGLOSSAL NERVE ( CN XII )XII )

Supply somatic motor fiber to the intrinsic Supply somatic motor fiber to the intrinsic and extrinsic muscles of the tongue, and extrinsic muscles of the tongue, except the palatoglossus.except the palatoglossus.

They arise by several rootlets between the They arise by several rootlets between the pyramids and the olives of the medulla.pyramids and the olives of the medulla.

They pass through the hypoglosal canals They pass through the hypoglosal canals and run inferiorly and anteriorly passing and run inferiorly and anteriorly passing medial to the angles of the mandible and medial to the angles of the mandible and between the mylohyoid and the between the mylohyoid and the hypoglossus to reach the muscles of the hypoglossus to reach the muscles of the tonguetongue