ANATOMY OF ANATOMY OF EAREAR

Presenter :Dr.Razal M Sherif

Moderator :Dr.Joythi swarup

EAREAR

EXTERNAL EARMIDDLE EARINNER EAR

EXTERNAL EAREXTERNAL EAR

AURICLE OR PINNAEXTERNAL AUDITORY CANAL

PINNAPINNASingle piece of yellow

elastic cartilage covered with Perichondrium and skin(except lobule and outer part of external auditory canal)

Attached to the side of skull by ligaments and muscles (supplied by facial nerve),muscles are not well developed in human

INCISURA TERMINALIS is a gap between the superior part of tragus and root of helix, which is devoid of cartilage having only fibrous tissue

◦ Endaural approach-inscion made on this area will not cut through the cartilage in surgery of EAC or Mastoid

PINNAPINNA Contd.Contd.

APPLIED ANATOMYAPPLIED ANATOMY

Tragal cartilage, perichondrium from tragus, concha, fat from lobule – reconstruction surgery for middle ear

Conchal cartilage – correct depressed nasal bridge

Composite graft of skin & cartilage from pinna – repair the defects of nasal ala

NERVE SUPPLY - PINNANERVE SUPPLY - PINNA

Greater auricular nerve◦ most of the medial surface

of pinna◦ posterior part of lateral

surface Lesser occipital

◦ upper part of medial surface

Auriculo temporal◦ tragus◦ crus of helix◦ adjacent part of helix

Auricular branch of vagus◦ concha◦ corresponding eminence on medial surface

Facial nerve◦ distributed with fibers of auricular branch of vagus◦ concha◦ retroauricular groove

NERVE SUPPLY – PINNA Contd

EXTERNAL AUDITORY CANALEXTERNAL AUDITORY CANAL

Extends from bottom of concha to tympanic membrane

24 mm (along post wall)not a straight tubeouter part(cartilaginous) directed upwards,

backwards & mediallyinner part (bony) directed downwards,

forwards & mediallypinna pulled upwards, backwards &

laterally(make it straight)

EXTERNAL AUDITORY CANALEXTERNAL AUDITORY CANAL

CARTILAGINOUSBONY

CARTILAGINOUS PARTCARTILAGINOUS PARTOuter 1/3rd & 8mm canalContinuation of cartilage which forms the

frame work of pinna

◦Fissures of Santorini through them parotid or superficial mastoid

infection can appear in the canal or vice versa

Skin covering the cartilaginous canal is thick and contains appendages like 1.CERUMINOUS GLANDS(modified sweat gland),which secrets cerumen (wax) 2.PILOSEBACEOUS GLANDS 3. HAIR is only confined to the outer canal & therefore furuncles are seen only in the outer 1/3rd of canal

BONY PARTBONY PARTInner 2/3rd & 16mmSkin lining the bony canal in thin & continuous

over the tympanic membrane Devoid of skin appendages(Hair and

ceremonious GlandsAbout 6mm lateral to tympanic membrane ,

bony meatus presents as narrowing called ISTHMUS

Foreign body lodged medial to isthmus, get impacted & are difficulty to remove

Anteroinferior part of deep meatus, beyond the isthmus, presents a recess - Anterior recess which acts as a cesspool for discharge & debris

Antero inferior part of bony canal may present a deficiency in children up to age of 4 or sometimes in adults permitting infection to & from parotid (Foramen of Huschke)

NERVE SUPPLY - EACNERVE SUPPLY - EACAuriculo temporal nerve(V3)◦anterior wall & roof

Auricular branch of vagus (X)◦posterior wall & floor

Posterior wall of auditory canal also receives sensory fibres of CN VII through auricular branch of vagus

TYMPANIC MEMBRANETYMPANIC MEMBRANEForms partition between

EAC & middle earObliquely set – 45deg

with floor of EACPosteriosuperior part

more lateral than Anterioinferior part

9-10 mm tall8-9 mm wide0.1 mm thick

PARS TENSAPARS FLACCIDA (SHRAPNEL’S

MEMBRANE)

TYMPANIC MEMBRANETYMPANIC MEMBRANE

PARS TENSAPARS TENSA

Forms most of Tympanic Membrane Periphery is thickened to form a fibro

cartilaginous ring – ANNULUS TYMPANICUS, which fits in tympanic sulcus

Central part of pars tensa is tented inwards at the level of tip of malleus – UMBO

Bright Cone of Light – seen radiating from the tip of malleus to periphery in anterioinferior quadrant

PARS FLACIDAPARS FLACIDA

Situated above lateral process of malleus between the notch of rivinus & anterior & posterior malleolar fold

Appear slightly Pinkish

LAYERS OF TYMPANIC MEMBRANELAYERS OF TYMPANIC MEMBRANEOuter Epithelial layer◦ continuous with skin lining the meatus

Inner mucosal layer◦ continuous with mucosa of middle ear

Middle fibrous layer◦ encloses the handle of malleus◦ 3 types of fibres

Radial Circular Parobolic

◦ Pars flacida – not organized(Fibrous Layers)

NERVE SUPPLY - TMNERVE SUPPLY - TMAURICULO TEMPORAL NERVE (V3)◦Anterior half of lateral surface

AURICULAR BRANCH OF VAGUS (X)◦Posterior half of lateral surface

TYMPANIC BRANCH OF CN IX (JACOBSON NERVE)◦Medial surface

ANATOMY OF EAR Video Presentation

THE MIDDLE EARTHE MIDDLE EAR EUSTACHIAN TUBE ANTERIORLY MIDDLE EAR CAVITY ATTIC ADITUS MASTOID ANTRUM MASTOID AIR CELLS POSTERIORLY

Middle Ear Cleft

MIDDLE EAR CAVITYMIDDLE EAR CAVITYROOF◦Thin Plate Of Bone – Tegmen Tympani◦Separates Middle Ear From Middle Cranial

Fossa◦Incomplete Ossification – Allow Infection To

Middle cranial fossa

FLOOR◦Thin bone separates cavity from jugular bulb

LATERAL WALL◦Main Part – Tympanic Membrane ◦Superiorly Area Of Bone – Scutum◦Inferiorly – Tympanic Bone Separates

Tympanic Cavity From Medial Part Of TMJ

ANTERIOR WALL◦Narrow inferiorly◦Thin plate of bone separates the cavity from

internal carotid artery.◦2 openings in upper part of anterior wall◦Above – opening for tensor tympani◦Below – opening for Eustachian tube

MEDIAL WALL◦ Promontory – bulging part on medial wall overlies the

basal turn of cochlea◦ Postero-superior to promontory is oval window ◦ Post-inferior is round window◦ Post-superior to promontory – horizontal part of

facial nerve runs antero-posteriorly in fallopian canal◦ Processus cochleariformis – projection anteriorly

which marks the start of horizontal portion of facial nerve

◦ 2 bony ridges (Ponticulus & Subiculum)

Groove above the ponticulus is oval window region (fenestra vestibuli) which is closed by foot plate of stapes

Groove below the scubiculum is round window region (fenestra cochlea) which is sealed by secondary tympanic membrane

Area between ponticulus & scubiculum is sinus tympani Bounded laterally by mastoid segment of facial nerve &

medially by medial wall of tympanum

FACIAL RECESS BOUNDARIES◦ LATERALLY – postero superior part of anulus◦ SUPERIORLY – short process of incus in fossa incudis◦MEDIALLY – vertical part of facial nerve

Explored during posterior tympanotomy procedure which is widely used during ci & combined approach tympanoplasty

POSTERIOR WALL

◦ SUPERIORLY – aditus ad antrum which leads from epitympanum to mastoid antrum

◦ INFERIOR TO ADITUS – small conical projection – pyramid transmits the stapedial tendon to its insertion at the neck of stapes

◦ below pyramid & lateral to it is opening for chorda tympani

DIVISIONS OF MIDDLE EAR DIVISIONS OF MIDDLE EAR CAVITYCAVITYEPITYMPANUM

◦ part of middle ear above the malleolar fold◦ contains head of malleus, body of incus, ossicular

ligament & mucosal fold◦ prussacs space – situated in attic

laterally – pars flaccida medially – head & neck of malleus anterosuperiorly – lateral malleolar ligament inferiorly – ant & post malleolar fold

◦ site of formation of primary acquired cholesteotoma

MESOTYMPANUM◦Part lying medial to pars tensa & is major air

filled space◦Contains – long process of incus, stapes,

mucosal fold

HYPOTYMPANUM◦Part lying below the lower margin of tympanic

membrane◦Contains globus body & bulge produced by

jugular bulb◦Floor may be deficient sometimes & thus

jugular bulb may project into tympanic cavity

PROTYMPANUM

◦Portion of middle ear around the tympanic orifice of et

CONTENTS OF MIDDLE EAR CONTENTS OF MIDDLE EAR CAVITYCAVITY3 BONY OSSICLES◦MALLEUS◦INCUS◦STAPES

INTRA TYMPANIC MUSCLES◦TENSOR TYMPANI◦STAPEDIUS MUSCLE

TYMPANIC PLEXUSCHORDA TYMPANI NERVE & VESSELS

MASTOID PROCESS & AIR MASTOID PROCESS & AIR CELLSCELLSPart of Temporal boneAt Birth – No Mastiod ProcessStarts developing at the end of first year 3 TYPES ◦CELLULAR◦SCLEROTIC◦DIPLOEIC

MASTIOD ANTRUMMASTIOD ANTRUMBiggest & most constant air cellANTERIORLY – tympanic cavity thru aditusPOSTERIORLY to other air cellsMEDIAL WALL – petrous portion of temporal

boneLATERAL WAll – squamous portion of temporal

boneROOF – tegmen antriFLOOR – mastoid portion

MAC EVENMAC EVEN’’S TRIANGLES TRIANGLEsurgical land mark for mastoid antrumBoundaries◦ Above – suprameatal crest◦ Front – posterosuperior margin of bony eac◦ Behind – tangential line from posterior meatal wall

lies 1.5 cm depthlies above & behind the projection of bone –

spine of henlekorner’s septum

VARIOUS GROUPS OF AIR CELLSVARIOUS GROUPS OF AIR CELLSMASTOID AIR CELLSMASTOID AIR CELLS LOCATIONLOCATION

PERISINUS CELLSPERISINUS CELLS SIGMOID SINUSSIGMOID SINUS

PERILABYRINTHINE CELLSPERILABYRINTHINE CELLS LABYRINTH(SUPRA, INFRA, RETRO)LABYRINTH(SUPRA, INFRA, RETRO)

TEGMEN CELLSTEGMEN CELLS TEGMEN TYMPANITEGMEN TYMPANI

ZYGOMATIC CELLSZYGOMATIC CELLS ROOT OF ZYGOMAROOT OF ZYGOMA

PETROUS CELLSPETROUS CELLS PETROUS APEXPETROUS APEX

PERITUBAL CELLSPERITUBAL CELLS ETET

RETROFACIAL CELLSRETROFACIAL CELLS VERTICAL SEGMENT OF FACIAL NERVEVERTICAL SEGMENT OF FACIAL NERVE

TIP CELLSTIP CELLS MASTOID TIP(LATERAL & MEDIAL)MASTOID TIP(LATERAL & MEDIAL)

PERIANTRAL CELLSPERIANTRAL CELLS MASTOID ANTRUMMASTOID ANTRUM

SQUAMOUS CELLSSQUAMOUS CELLS SQUAMOUS PART OF TEMPORAL BONESQUAMOUS PART OF TEMPORAL BONE