final cranial nerves

8/3/2019 Final Cranial Nerves

http://slidepdf.com/reader/full/final-cranial-nerves 1/36

The Cranial Nerves

PG 1 ST Yr.(Dept. of Radiology & Imaging)



Names of cranial nervesO lfactory nerveO ptic nerveO culomotor nerveTrochlear nerve

Trigeminal nerve Ab ducent nerveF acial nerveV esti b ulocochlear nerve

Glossopharyngeal nerveV agus nerve A ccessory nerveH ypoglossal nerve



Fu nctional componentsGeneral somatic afferent fibers (GSA): transmit exteroceptiveand proprioceptive impulses from head and face to somatic

sensory nucleiSpecial somatic afferent fibers (SSA): transmit sensory impulsesfrom special sense organs of vision, equili b rium and hearing to theb rainGeneral visceral afferent fibers (GVA): transmit interoceptiveimpulses from the viscera to the visceral sensory nucleiSpecial visceral afferent fibers (SVA): transmit sensory impulsesfrom special sense organs of smell and taste to the b rainGeneral somatic efferent fibers (GSE): innervate skeletalmuscles of eye and tongueSpecial visceral efferent fibers (SVE): transmit motor impulsesfrom the b rain to skeletal muscles derived from b rachial (gill)arches of em b ryo. These include the muscles of mastication, facial

expression and swallowingGeneral visceral efferent fibers (GVE): transmit motor impulsesfrom the general visceral motor nuclei and relayed inparasympathetic ganglions. The postganglionic fi b ers supplycardiac muscles smooth muscles and glands



Classification of cranial nervesSensory cranial nerves : contain only afferent (sensory) fi b ers

O lfactory nerveO ptic nerveVestibulocochlear nerve

Motor cranial nerves : contain only efferent (motor) fi b ersO culomotor nerveT rochlear nerve

Abducent nerveAccessory nervH ypoglossal nerve

Mixed nerves : contain b oth sensory and motor fi b ers---T rigeminal nerve,F acial nerve,

Glossopharyngeal nerveVagus nerve



S ensory cranial nervesN. L ocation of cellbody and axon

categories

CranialexitTerminalnuclei Main action

O lfactory cells(SVA)

Cribrifomforamina

O lfactorybulb

Smell

Ganglion cells(SSA)

O pticcanal

L ateralgeniculatebody

Vision

Vestibular ganglion(SSA)

Internalacousticmeatus

Vestibular nuclei

Equilibrium

Cochlear ganglion (SSA)

Cochlear nuclei

H earing



Cranial Nerve I: Olfactory

A rises from the olfactory epitheliumPasses through the cri b riform plate of the

ethmoidb

oneF ib ers run through the olfactory b ulb andterminate in the primary olfactory cortexF unctions solely b y carrying afferent impulsesfor the sense of smell



O lfactory nerve

O lfactory mucosa (SVA) Cribriform foramina O lfactorybulb



Cranial Nerve II: Optic

A rises from the retina of the eyeO ptic nerves pass through the optic canals andconverge at the optic chiasmThey continue to the thalamus where theysynapseF rom there, the optic radiation fi b ers run to the

visual cortexF unctions solely b y carrying afferent impulsesfor vision



O ptic nerveGanglion cell (SSA) O ptic canal L ateral geniculate body



V estib u locochlear nerveVestibular ganglion(SSA) Vestibular nuclei

Internal acoustic meatusCochlear ganglion (SSA) Cochlear nuclei

O rigins -- arises from the cochlear and vestibular portions of the inner ear

Sensory functions -- senses of equilibrium and hearing

Motor functions -- none



M otor cranial nervesN. N ucleus of origin and

axon categoriesCranial exit Main action

N ucleus of oculomotor (GSE)

Superior orbitalfissure

Motor to superior, inferior and medial recti; inferior obliquus; levator palpebrae superioris

Accessory nucleus of oculomotor (GVE)

Parasympathetic tosphincter pupillea andciliary muscl

N ucleus of trochlear nerve (GSE)


Motor to superior obliquus

N ucleus of abducentnerve (GSE)


Motor to lateral rectus

N ucleus of accessorynerve (SVE)

Jugular foramen Motor tosternocleidomastoid andtrapezius

N ucleus of hypoglossalnerve( GSE)

H ypoglossal canal Motor to muscles of tongue



Components

General somatic efferent fi b ers (GSE)General visceral efferent fi b ers (G V E)Main action supplies

Superior, inferior and medial recti; inferior o b liquus; levator palpe b raesuperiorisSphincter pupillea and ciliary muscle

Ciliary ganglion: lies b etween optic nerve and lateral rectus

O culomotor nerve

O culomotor N erves C N III



H ypoglossal nerve

H ypoglossal nerve



M ixed cranial nerves



Trigeminal nerve

Components of fibersSVE fibers : originate from motor nucleus of trigeminal nerve, and supply masticatorymusclesGSA fibers : transmit facial sensation to sensorynuclei of trigeminal nerve, the GS A fib ers havetheir cell b odies in trigeminal ganglion, which lieson the apex of petrous part of temporal b one



B ranchesO phthalmic nerve( 1, sensory) leavethe skull through thesuperior or b ital fissure, toenter or b ital cavityB ranches

F rontal nerve : Supratrochlear nerveSupraor b ital nerve

Lacrimal nerveNasociliary nerve

Distri b ution : Sensation fromcere b ral dura mater V isual organMucosa of noseSkin a b ove the eye andb ack of nose



Maxillary nerve( 2 , sensory)Leave skull throughforamen rotundumB ranches

Infraor b

ital nerveZygomatic nerveSuperior alveolar nerve

Pterygopalatinenerve

D istribution : Sensation from cere b raldura mater Maxillary teethMucosa of nose andmouthSkin b etween eye andmouth



Mandibular nerve ( 3 ,

mixed)Leave the skull through theforamen ovale to enter theinfratemporal fossaB ranches

Auriculotemporal nerveB uccal nerveL ingual nerveInferior alveolar nerveN erve of masticatorymuscles

D istribution :

Sensation from cereb

raldura mater Teeth and gum of lower

jawMucosa of floor of mouthA nterior 2/3 of tongueSkin of auricular andtemporal regions and b elowthe mouthMotor to masticatorymuscles, mylohyoid, andanterior b elly of digastric



F acial nerve ( )

Components of fibersSVE fib ers originate from nucleus of facial nerve, and supplyfacial muscles

GVE fib ers derived from superior salivatory nucleus and relayed

in pterygopalatine ganglion and su b mandi b ular ganglion. Thepostganglionic fi b ers supply lacrimal, su b mandi b ular andsu b lingual glands

SVA fib er from taste b uds of anterior two-thirds of tongue which

cellb

odies are in the geniculate ganglion of the facial nerve andend b y synapsing with cells of nucleus of solitary tract

GSA fib ers from skin of external ear



Course : leaves skullthrough internal acousticmeatus, facial canal andstylomastoid foramen, itthen enters parotid glandwhere it divides into fiveb ranches which supplyfacial muscles



B ranches within the facial canalChorda tympani : joins lingual b ranch of mandi b ular nerve

To taste b uds on anterior two-thirds of tongue

Relayed in su b mandi b ular ganglion, the postganglionic fi b ers supplysu b mandi b ular and su b lingual glands

Greater petrosal nerve : GV E fib ers pass to pterygopalatine ganglion

and there relayed through the zygomatic and lacrimal nerves to lacrimalgland

Stapedial nerve : to stapedius



B ranches outside of facial canal

TemporalZygomaticB uccalMarginal mandi b ular

Cervical



Pterygopalatine ganglion : lies in pterygopalatinefossa under maxillary nerve

Submandibular ganglion : lies b etween lingualnerve and su b mandi b ular gland



G lossopharyngeal nerve ( )

Components of fibersSVE fib ers : originate from nucleus am b iguus, and supplystylopharygeusGVE fib ers : arise from inferior salivatory nucleus and ralyedin otic ganglion, the postganglionic fi b ers supply parotid gland

SVA fib

ers:

arise from the cells of inferior ganglion, thecentral processes of these cells terminate in nucleus of solitary tract, the peripheral processes supply the taste b udson posterior third of tongueGVA fib ers : visceral sensation from mucosa of posterior thirdof tongue, pharynx, auditory tu b e and tympanic cavity,carotid sinus and glomus, and end b y synapsing with cells of nucleus of solitary tractGSA fib ers : sensation from skin of posterior surface of auricle and



Course : leaves the skull via jugular foramenB ranches

L ingual branches : to taste b uds and mucosa of posterior third of tongue

Pharyngeal b ranches : take part in forming the pharyngeal plexus

Tympanic nerve : GV E fib ers via tympanic and lesser petrosalnerves to otic ganglion, with postganglionic fi b ers via

auriculotemporal ( 3 ) to parotid glandCarotid sinus branch : innervations to b oth carotid sinus and glomusO thers : tonsillar and stylophayngeal b ranches

O tic ganglion : situated just b elow foramen ovale



V ag u s nerve ( )

components of fibersGVE fib ers : originate from dorsal nucleus of vagus nerve, synapse in parasympatheticganglion, short postganglionic fi b ers innervatecardiac muscles, smooth muscles and glands of visceraSVE fib ers : originate from am b iguus, to musclesof pharynx and larynxGVA fib ers : carry impulse from viscera in neck,

thoracic and a b dominal cavity to nucleus of solitary tractGSA fib er : sensation from auricle, externalacoustic meatus and cere b ral dura mater



CourseExits the skull from jugular foramenD escends in the neck in carotid sheath betweeninternal (or common) carotid artery and internal

jugular vein

Right vagus nerveEnter thoracic inlet on right side of trachea

T ravels downward posterior to rightbrachiocephalic vein and superior vena cava

Passes posterior to right lung rootF orms posterior esophageal plexusF orms posterior vagal trunk at esophageal hiatus

where it leaves thorax and passes into abdominalcavity, then divides into posterior gastric andceliac branches



L eft vagus nerveEnter thoracic inlet b etween left common

carotid and left su b clavian arteries, posterior toleft b rachiocephalic vein

Crosses aortic arch where left recurrentlaryngeal nerve b ranches off

Passes posterior to left lung rootF orms anterior esophageal plexusF orms anterior vagal trunk at esophagealhiatus where it leaves thorax and passes intoa b dominal cavity , then divides into anterior

gastric and hepaticb

ranches



B ranches in neck

Superior laryngeal nerve:

passes downside of pharynx and given rise toInternal b ranch , which pierces thyrohyoidmem b rane to innervates mucous mem b rane of

larynx ab

ove fissure of glottisExternal b ranch , which innervates cricothyroid

Cervical cardiac b ranches : descending toterminate in cardiac plexusO thers : auricular, pharyngeal andmeningeal b ranches



Superior laryngeal nerve

External branch

Internal branch



B ranches in thoraxRecurrent laryngeal nerves

Right one hooks around right su b clavianartery, left one hooks aortic archB oth ascend in tracheo-esophagealgroove

Nerves enter larynx posterior tocricothyroid joint, the nerve is nowcalled inferior laryngeal nerve

Innervations : laryngeal mucosa b elowfissure of glottis , all laryngeal laryngeal

muscles except cricothyroidB ronchial and esophageal b ranches



B ranches in abdomenAnterior and posterior gastricbranches

Run close to lesser curvatureand innervate anterior andposterior surfaces of stomachA s far as pyloric antrum to fanout into b ranches in a way likethe digits of a crow¶s foot tosupply pyloric part

H epatic branches : join hepaticplexus and then supply liver andgall b ladder Celiac branches : sendb ranches to celiac plexus to b edistri b uted with sympathetic

fib ers to liver, pancreas, spleen,kidneys, intestine as far as leftcolic flexure

final cranial nerves

Documents