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ANATOMY OF ANATOMY OF EXTERNAL EAREXTERNAL EAR
Presenter :Dr.Razal M Sherif
Moderator :Dr.Joythi swarup
EAREAREXTERNAL EARMIDDLE EARINNER EAR
EXTERNAL EAREXTERNAL EARAURICLE 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 CANALExtends 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 & roofAuricular branch of vagus (X)
◦posterior wall & floorPosterior 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 meatusInner mucosal layer
◦ continuous with mucosa of middle earMiddle 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 surfaceAURICULAR BRANCH OF VAGUS (X)
◦Posterior half of lateral surfaceTYMPANIC BRANCH OF CN IX (JACOBSON
NERVE)◦Medial surface
ANATOMY OF EAR Video Presentation