It is divided intoIt is divided into::External earExternal ear..

Middle ear Middle ear (Tympanic (Tympanic cavity)cavity)..

Internal ear Internal ear (Labyrinth)(Labyrinth) . .

AuricleAuricle: : Attached to the lateral Attached to the lateral

aspect of the headaspect of the head..External Auditory External Auditory (Acoustic)(Acoustic)

meatusmeatus:: A canal leading inwardsA canal leading inwards..

It is (S) shaped tubeIt is (S) shaped tube. . ((2.52.5 cmcm ) )in adultsin adults..Its lateral 1/3 isIts lateral 1/3 is

CartilaginousCartilaginous.. It is lined withIt is lined with SkinSkin..

It contains hairs, sebaceous It contains hairs, sebaceous and many Ceruminous and many Ceruminous glandsglands

Its medial 2/3 is Its medial 2/3 is BonyBony.. Formed mainly by the Formed mainly by the

TTympanic Plateympanic Plate..It is lined by thin skinIt is lined by thin skin . .

Nerve SupplyNerve Supply : : Auriculotemporal nerveAuriculotemporal nerve..

Auricular branch of the Auricular branch of the vagusvagus..

The meatus has to be straight .

It is pulledIn Children:

Straight backward or downward and backward.

In Adults: Upward and

backward.

It is an oval, thin It is an oval, thin semitransparent semitransparent membrane (1 cm) membrane (1 cm) in diameterin diameter . .

It forms a It forms a Partition Partition between the between the external meatus external meatus and the tympanic and the tympanic cavitycavity . .

A shallow cone like A shallow cone like central depression , its central depression , its peak is the peak is the UmboUmbo..

Cone of lightCone of light radiates radiates antero inferior from the antero inferior from the umboumbo . .

Pars FlaccidaPars Flaccida::The thin superior part of The thin superior part of

the membranethe membrane..Pars TensaPars Tensa::

The rest of the The rest of the membranemembrane . .

It is thick and tautIt is thick and taut..

The tympanic membrane The tympanic membrane is extremely is extremely sensitivesensitive to to painpain..

Outer surfaceOuter surface ( (mainlymainly))::Auriculotemporal nerveAuriculotemporal nerve

Auricular branch of the Auricular branch of the vagusvagus..

Internal surfaceInternal surface: : Glossopharyngeal nerveGlossopharyngeal nerve..

It is an air- filled It is an air- filled mucous membrane mucous membrane lined space in the lined space in the temporal bonetemporal bone..

It is betweenIt is between:: LaterallyLaterally::

The Tympanic The Tympanic membranemembrane . .

MediallyMedially:: The lateral wall of the The lateral wall of the

inner earinner ear..

((11 ) )Tympanic CavityTympanic Cavity:: A space directly A space directly

internal to the internal to the tympanic membranetympanic membrane..

((22)) Epitympanic Epitympanic RRecessecess::

A space superior to A space superior to the tympanic cavitythe tympanic cavity..

((11 ) )AnteriorAnterior:: NasopharynxNasopharynx

((22 ) )Postero Postero superiorsuperior::

Mastoid air cellsMastoid air cells..

Tegmental WallTegmental Wall::A thin plate of bone A thin plate of bone

(Tegmen Tympani)(Tegmen Tympani) on on the anterior surface of the anterior surface of the petrous part of the petrous part of temporal bonetemporal bone..

It separates the cavity It separates the cavity fromfrom::

Middle Cranial FossaMiddle Cranial Fossa..

Jugular wallJugular wall::It is a thin plate of It is a thin plate of

bonebone . .It separates the cavity It separates the cavity

from the from the Superior Bulb Superior Bulb of IJVof IJV..

It may be deficient or It may be deficient or replaced by fibrous replaced by fibrous tissuetissue..

MembranousMembranous::Almost totally it is the Almost totally it is the

TympanicTympanic MembraneMembrane..SuperiorlySuperiorly::

Epitympanic RecessEpitympanic Recess..

LabyrinthineLabyrinthine11 . .PromontoryPromontory::

AA central bulgecentral bulge . . Produced by the basal coil of the Produced by the basal coil of the

CochleaCochlea22 . .Tympanic PlexusTympanic Plexus..

On the mucous membrane of the On the mucous membrane of the promontorypromontory . .

33 . .Fenestra VestibuliFenestra Vestibuli:: ((Oval WindowOval Window))

It is above and behind the It is above and behind the PromontryPromontry..

44 . .Fenestra CochleaFenestra Cochlea (Round (Round window)window)..

The windows lead to Perilymph of The windows lead to Perilymph of internal earinternal ear . .

55 . .Prominence of Prominence of facial canalfacial canal::

posterior and posterior and superior to the oval superior to the oval windowwindow..

Produced by the Produced by the Facial nerve in its Facial nerve in its canalcanal..

66.. Prominence of Prominence of lateral semicircular lateral semicircular canalcanal..

A pathological A pathological process affecting the process affecting the mucosa of the mucosa of the OvalOval windowwindow and the and the mastoid processmastoid process . .

They are They are transformed into transformed into bonebone . .

It is complicated byIt is complicated by DeafnessDeafness..

CarotidCarotid: : LowerLower: :

A thin plate of boneA thin plate of bone . .It separates the tympanic It separates the tympanic

cavity from the Carotid cavity from the Carotid CanalCanal . .

Upper:Upper: Two openingsTwo openingsUpper smallerUpper smaller:: for the for the

Tensor TympaniTensor Tympani.. Lower larger:Lower larger: for the for the

Auditory TubeAuditory Tube..

Mastoid areaMastoid area ::A.A. AditusAditus

A large irregular opening A large irregular opening posterior to the epitympanic posterior to the epitympanic recessrecess..

B. Mastoid antrumB. Mastoid antrum: : A cavityA cavity continuous with air filled continuous with air filled

spaces within the mastoid spaces within the mastoid processprocess..

C. PyramidC. Pyramid:: The tendon of The tendon of Stapedius muscleStapedius muscle

emerges from its apexemerges from its apex..

Roof Roof :: Tegmen Tympani Tegmen Tympani . .Floor :Floor : Many openings Many openings

To communicate with the mastoid To communicate with the mastoid air cellsair cells..

AnteriorAnterior :: Middle ear & AditusMiddle ear & Aditus..

PosteriorPosterior:: Sigmoid Sinus & CerebellumSigmoid Sinus & Cerebellum..

LateralLateral:: Floor of Suprameatal TriangleFloor of Suprameatal Triangle..

MedialMedial:: Posterior Semicircular CanalPosterior Semicircular Canal..

11 . .Auditory OssiclesAuditory Ossicles..22 . .MusclesMuscles..

33 . .NervesNerves..

They extend from the tympanic They extend from the tympanic membrane to the oval windowmembrane to the oval window..

They are present at They are present at BirthBirth..Not covered by Not covered by PeriosteumPeriosteum..

MalleusMalleus:: The largest and attached to the The largest and attached to the

tympanic membranetympanic membrane . .StapesStapes::

Occupies the oval windowOccupies the oval window. . IncusIncus::

Between the two bonesBetween the two bones..Their decreased mobility in old Their decreased mobility in old

age is responsible for degrees of age is responsible for degrees of DeafnessDeafness..

It lies in a bony canal It lies in a bony canal above the above the Pharyngotympanic tubePharyngotympanic tube..

InsertionInsertion:: Handle of the malleusHandle of the malleus..

ActionAction::Pulles the handle mediallyPulles the handle medially . .

Tenses the tympanic Tenses the tympanic membranemembrane . .

Reduces the amplitude of Reduces the amplitude of its oscillationsits oscillations . .

Nerve supplyNerve supply : : MandibularMandibular

The smallest voluntary muscle of The smallest voluntary muscle of the bodythe body..

OriginOrigin:: From inside the pyramidal From inside the pyramidal

eminenceeminence..InsertionInsertion::

Neck of the stapesNeck of the stapes..ActionAction::

Pulls the stapes posteriorlyPulls the stapes posteriorly . .Reduces the oscillatory range Reduces the oscillatory range

and prevents its excessive and prevents its excessive movementsmovements..

Nerve supplyNerve supply : : Facial nerveFacial nerve..

A branch of A branch of Glossopharyngeal nerveGlossopharyngeal nerve . .

Passes through the floor of Passes through the floor of the middle ear and onto the the middle ear and onto the PromontryPromontry..

GivesGives::Tympanic PlexusTympanic Plexus::

It associates the It associates the Caroticotympanic PlexusCaroticotympanic Plexus to to supply mucous membrane supply mucous membrane of middle earof middle ear..

Lesser Petrosal nerveLesser Petrosal nerve: : To Otic GanglionTo Otic Ganglion..

EntersEnters:: 11..Internal acoustic Internal acoustic

meatus meatus in close in close company with the 8company with the 8thth nervenerve..

22 . .Facial CanalFacial Canal.. It continues laterally It continues laterally

between the inner and between the inner and middle earsmiddle ears..

It expands to form theIt expands to form the Geniculate GanglionGeniculate Ganglion..

At theAt the posterior wallposterior wall:: CurvesCurves downward in downward in

a vertical directiona vertical direction..LiesLies: :

Medial to the AditusMedial to the Aditus . .Behind the PyramidBehind the Pyramid . .

ExitsExits:: Through the Through the

Stylomastoid Stylomastoid ForamenForamen..

11 . .Greater Petrosal Greater Petrosal nervenerve..

It is the first branch It is the first branch from the Geniculatefrom the Geniculate

GanglionGanglion..It carries preganglionic It carries preganglionic

parasympathetic to the parasympathetic to the Pterygopalatine Pterygopalatine GanglionGanglion..

It suppliesIt supplies:: Lacrimal , Nasal and Lacrimal , Nasal and

Palatine glandsPalatine glands..

22 . .Nerve to Nerve to StapediusStapedius..

33 . .Chorda TympaniChorda Tympani::It arises just before It arises just before

the facial nerve the facial nerve exitsexits..

It ascends to enter It ascends to enter the middle ear the middle ear through its through its posterior wallposterior wall..

Connects the Connects the TympanicTympanic Cavity Cavity to the to the NasopharynxNasopharynx..

Its Postero lateral 1/3 is Its Postero lateral 1/3 is bonybony . .

The remainder isThe remainder is CartilaginousCartilaginous..

Its walls are normally in Its walls are normally in appositionapposition..

The tube is actively The tube is actively opened by swallowing opened by swallowing and yawingand yawing

FunctionFunction :: Equalizes pressure in the Equalizes pressure in the

middle ear with the middle ear with the atmospheric pressureatmospheric pressure..

It is a pathway of It is a pathway of infection from the throat infection from the throat to the tympanic cavity to the tympanic cavity and mastoid air cellsand mastoid air cells . .

Nerve supply :Nerve supply : tympanic tympanic plexusplexus..

A series of bony A series of bony cavities in the cavities in the Petrous part of Petrous part of temporal bonetemporal bone..

It is composed ofIt is composed of::CochleaCochlea..

VestibuleVestibule..Semicircular CanalsSemicircular Canals..

They contain They contain PerilymphPerilymph..

CochleaCochlea::It is shell shapedIt is shell shaped. .

Its first turn produces the Its first turn produces the PromontoryPromontory..

VestibuleVestibule: : It is in a central positionIt is in a central position..

It has theIt has the Oval Oval and and Round Round Windows in its lateral wallWindows in its lateral wall..

Semicircular canalsSemicircular canals: : Posterior, superior and LateralPosterior, superior and Lateral..

They communicate with the They communicate with the VestibuleVestibule..

It consists ofIt consists of:: Four DuctsFour Ducts::

CochlearCochlearThreeThree SemicircularSemicircular

Two SacsTwo Sacs::UtricleUtricle.. SacuuleSacuule..

It is filled withIt is filled with EndolymphEndolymph..

It is separated from the It is separated from the periosteum of the bony periosteum of the bony labyrinth by labyrinth by PerilymphPerilymph..

The cochlea is divided into The cochlea is divided into two canals containingtwo canals containing PerilymphPerilymph by the centrally by the centrally located cochlear ductlocated cochlear duct..

The duct hasThe duct has: : Roof : Roof : Vestibular Vestibular

membranemembrane..Floor :Floor : Basilar membrane Basilar membrane..

The Spiral OrganThe Spiral Organ (organ of (organ of hearing) rests on the hearing) rests on the basilar membranebasilar membrane..

UtricleUtricle.. SaculeSacule

Three Semicircular Three Semicircular DuctsDucts..

The The Utricosaccular DuctUtricosaccular Duct establishesestablishes

continuity between all continuity between all components of the components of the membranous labyrinthmembranous labyrinth..

The EndolymphaticThe Endolymphatic DuctDuct branches from it branches from it..

It emerges onto the It emerges onto the posterior surface of posterior surface of the petrous part of the petrous part of the temporal bonethe temporal bone..

It expands to form an It expands to form an Extradural PouchExtradural Pouch Endolymphatic SacEndolymphatic Sac..

Divides intoDivides into: : A. Vestibular nerveA. Vestibular nerve: :

It enlarges to form the It enlarges to form the Vestibular GanglionVestibular Ganglion..

It suppliesIt supplies:: Three semicircular ductsThree semicircular ducts..

Utricle Utricle & & SacculeSaccule..B. Cochlear nerveB. Cochlear nerve::

It enters the base of the It enters the base of the cochleacochlea . .

It innervates the receptors inIt innervates the receptors in the the Spiral OrganSpiral Organ..