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CRANIAL NERVES
DR VINIT K ASHOK
ADJUNCT FACULTY
CRANIAL NERVES• NERVES COMING OUT/ GOING INTO THE
BRAIN
• TOTAL -12 NUMBERED IN ROMAN NUMERICALS( I-XII)
• CARRY IMPULSES TO AND FROM THE BRAIN
• EXIT OR ENTER THE SKULL THROUGH OPENINGS IN THE SKULL
• I AND 11 ARE ATTACHED TO THE FOREBRAIN
• III TO XII ARE ATTACHED TO THE BAIN STEM
• ALL SUPPLY THE STRUCTURES OF THE HAED AND NECK EXCEPT THE X( VAGUS) ----VAGABOND -----WANDERS TO THE ABDOMEN
• I – OLFACTORY
• II- OPTIC
• III-OCCULOMOTOR
• IV-TROCHLEAR
• V-TRIGEMINAL( 3 DIVISIONS)
• VI –ABDUCENS
• VII-FACIAL
• VIII-VESTIBULOCOCHLEAR
• IX-GLOSSOPHARYNGEAL
• X-VAGUS
• XI-ACCESSORY
• XII-HYPOGLOSSAL
• “OH OH OH TO TOUCH AND FEELVERY GOOD VELVET AH
FORAMINA /OPENINGS FOR THE CRANIAL NERVES
• I –OLFACTORY FORAMINA
• II-OPTIC FORAMEN
• III- SUPERIOR ORBITAL FISSURE
• IV-SUPERIOR ORBITAL FISSURE
• V- 3 DIVISIONS
A) OPTHALMIC- SUPERIOR ORBITAL FISSURE
B) MAXIALLRY-FORAMEN ROTUNDUM
C) MANDIBULAR- FORAMEN OVALE
• VI-INFERIOR ORBITAL FISSURE
• VII- ENTERS THE INT ACCOUSTIC MEATUS---- EXITS THE SKULL THROUGH THE STYLOMASTOID FORAMEN
• VIII- INT ACCOUSTIC MEATUS
• IX-JUGULAR FORAMEN
• X-JUGULAR FORAMEN
• XI- JUGULR FORAMEN
• XII-HYPOGLOSSAL CANAL
• I-OLFACTORY NERVE-SENSORY NERVES OF SMELL
• II - OPTIC NERVE-SENSORY NERVE OF VISION
• III- OCCULOMOTOR-( EYE MOVER)-INNERVATES 4 EXTRINSIC MUSCLES OF THE EYEBALL
• 1V- TROCLEAR NERVE- ( MEANS PULLEY) –SUPPLIES THE SUPERIOR OBLIQUE MUSCLE OF THE EYEBALL
• V-TRIGEMINAL ( 3 FOLD) –THIS NERVE HAS 3 BRANCHES. SENSORY INNERVATION TO THE FACE AND MOTOR TO MUSCLES THAT HELP US CHEW( MASTICATE)
• VI-ABDUCENS NERVE- IT SUPPLIES THE MUSCLE OF THE EYEBALL THAT ABDUCTS THE EYE( LATERAL RECTUS)
• VII-FACIAL NERVE-INNERVATES MUSCLES OF FACIAL EXPRESSION
• VIII-VESTIBULOCOCHLEAR-SENSORY NERVE OF HEARING AND EQUILIBRIUM
• IX-GLOSSOPHARYNGEAL NERVE-( MEANS TONGUE AND PHARYNX), STRUCTURES THIS NERVE INNERVATES
• X-VAGUS ( WANDERER)-INNERVATES THE STRUCTURES IN THE THORAX AND ABDOMEN
• XI-ACCESSORY- ( ACCESSORY TO THE VAGUS)-SUPPLIES THE TRAPEZIUS AND STERNOCLEIDOMASTOID
• XII-HYPOGLOSSAL( BELOW THE TONGUE)-RUNS INFERIOR TO THE TONGUE AND SUPPLIES THE TONGUE MUSCLES
SENSORY/MOTOR NERVE• CRANIAL NERVES --- PURELY
SENSORY / MOTOR / MIXED SENSORY NERVE- RECEPTORS----
GENARAL SENSATIONS( TOUCH, PAIN TEMP,PRESSURE,) SPECIAL --- SMELL,VISION, HEARING, EQUILIBRIUM.---CRANIAL NERVE—BRAIN.( I, II AND VIII) ( AFFERENT IMPULSES)
MOTOR NERVE-IMPULSE FROM THE BRAIN----CRANIAL NERVE ----ACTION----( MUSCLE/GLAND)----EFFERENT IMPULSES( III,IV,VI,XI AND XII)
MIXED ( BOTH TYPE OF FIBRES)
NERVES
• MOTOR ( TYPES)
• 1. VISCERAL MOTOR
- ( MOTOR NERVE SUPPLY TO THE VISCERA AND GLANDS)
2. BRANCHIAL MOTOR
MOTOR NERVE SUPPLY OF THE BRANCHIAL ARCH MUSCULATURE
3. SOMATIC MOTOR
MOTOR SUPPLY TO ALL OTHER SKELETAL MUSCLES
• SENSORY
1.VISCERAL SENSORY
A) SPECIAL—TASTE
B) GENERAL---VISCERA—PAIN,TOUCH,PRESSURE,
TEMP
2.SOMATIC SENSORY
A) SPECIAL- SMELL, VISION HEARING
B) GENERAL—TOCH ,PAIN PRESSURE FROM THE LIMBS, BODY WALL
CRANIAL NERVES WITH PARASYMPATHETIC FIBRES
• III- OCCULOMOTOR
-1. CONTRICTOR PUPILLAE
2. CILIARIS- CHANGES THE SHAPE OF THE LENS
• VII- FACIAL
1. TEAR , NASAL AND PALTINE GLANDS
2. SUBMANDIBULAR AND SUBLINGUAL GLANDS• IX- GLOSSOPHARYNGEAL
1. PAROTID GLAND
X- VAGUS
1. THORACIC AND ABDOMINAL VISCERA
SPECIAL SENSESVISION
• ORGAN- EYE
• 1/6 TH SEEN OUTSIDE REST INSIDE---ORBITAL CAVITY( FAT)
• ACCESSORY STRUCTURES
1. Eyebrows
2. EYELIDS
3. CONJUNCTIVA
4. LACRIMAL APPARATUS
5. EXTRINSIC MUSCLES
EXTERNAL ANATOMY
CLINICAL CONDITIONS• CHALAZION-INFECTION OF THE
TARSAL GALNDS( MEBOMIAN )• STY- INFECTION OF THE CIALIARY
GLANDS• CONJUNCTIVITIS- ( PINK EYE) ---
INFLAMMANTION OF ?
LACRIMAL APPARATUS
EXTRINSIC MUSCLES OF THE EYE
EXTRINSIC MUSCLES
ANATOMY OF THE EYEBALL• FUNCTIONS
• A) PROTECTS AND SUPPORTS THE DELICATE PHOTORECEPTOR CELLS
• B)GATHERS,FOCUSES AND PROCESSES LIGHT INTO PRECISE IMAGES
PARTS
1. ANTERIOR POLE
2. POSTERIOR POLE
3. TUNICS( EXTERNAL WALL)
4. HUMORS( FLUID ) INSIDE
5. LENS
TUNICS
FIBROUS VASCULAR SENSORY
SCLERA
CORNEA
CHORIOD
CILIARY BODY
IRIS
RETINA
• FIBROUS TUNIC(OUTERMOST)• - DENSE CONNECTIVE TISSUE( PROTECTION, MUSCLES
INSERTED)• POSTERIOR 5/6TH ( SCLERA) –WHITE OF THE EYE• ANTERIOR 1/6TH TRANSPARENT –CORNEA( AVASCULAR)• LIMBUS• SCLERAL VENOUS SINUS( DRAINS AQUEOUS HUMOR)
• VASCULAR TUNIC( MIDDLE)• CHOROID, CILIARY BODT AND IRIS• CHOROID--- VASCULAR , PIGMENTED( LIGHT IS NOT
SCATTERED)• CILIARY BODY---CILIARY MUSCLE----CIRIARY PROCESSES• IRIS---( COLOR OF THE EYE)----CENTRAL OPENING ---PUPIL
INTERNAL ANATOMY
SAGITTAL SECTION INTERNAL ANATOMY
RETINA
• SENSORY(• INNERMOST)• RETINA( MOST IMPORTANT)
• OUTER ---PIGMENTED( PREVENTS LIGHT SCATTERING)
• INNER---NEURAL ( LIGHT SENSITIVE PHOTORECEPTOR CELLS, BIPOLAR AND GANLION CELLS
• PHOTORECTORS----RODS/ CONES
LIGHT
PHOTORECEPTOR
BIPOLAR CELLS
GANGLION CELLS
OPTIC NERVE
BRAIN
OPTIC NERVE
EAR• RECEPTOR ORGAN FOR
HEARING AND EQUILIBRIUM• OUTER/ MIDDLE EAR------
HEARING• INNER
EAR----HEARING/EQUILIBRIUM• OUTER EAR• PINNA---AURICLE( ELASTIC
CARTILGE,EXCEPT—LOBULE)• EXT ACOUSTIC MEATUS—
2.5MM TUBE---AURICLE----EAR DRUM( EAR WAX)
• EAR DRUM---TYMPANIC MEMBRANE---BOUNDARY BETWEEN OUTER AND MIDDLE EAR
SOUND WAVES
EAR DRUM
OSSICLES
INNER EAR
MIDDLE EAR
• ALSO CALLED TYMPANIC CAVITY• AIR FILLED / INSIDE THE PETROUS TEMPORAL• LATERAL BOUNDARY—TYMPANIC MEMBRANE, MEDIAL
BOUNDARY—BONE SEPERATING IT FROM THE MIDDLE EARSUPERIOR BOUNDARY-PETROUS TEMPORALPOSTERIOR WALL—MASTOIOID ANTRUMINFERIOR BOUNDARY----BONE/IJVANTERIOR BOUNDARY-BEHIND ICA• MEDIAL WALL---OVAL AND ROUND WINDOW• PHARYNGOTYMPANIC TUBE CONNECTS IT TO THE
NASOPHARYNX• OSSICLE ARE PRESENT • 2 MUSCLES- STAPEDIUS/ TENSOR TYMPANI
INNER EAR
• ALSO CALLED LABYRINTH( MAZE LIKE)
• BONY LABYRINTH/MEMBRANOUS LABYRINTH
• BONY---PETROUS TEMPORAL----SEMICIRCULAR CANALS, VESTIBULE AND COCHLEA----PERILYMPH
• MEMBRANOUS –SMICIRCULAR DUCTS,UTRICLE, SACCULE, COCHLEAR DUCT
SEMICIRCULAR CANALS
VESTIBULE SEMICIRCULAR DUCTS
UTRICLE/SACCULE
EQUILIBRIUM
HEARING
COCHLEA
COCHLEAR DUCT