Anatomy of external ear

Anatomy of external ear

1. ANATOMY OF ANATOMY OF EXTERNAL EAREXTERNAL EAR
Presenter :Dr.Razal M Sherif
Moderator :Dr.Joythi swarup

2. EAREAR
EXTERNAL EAR
MIDDLE EAR
INNER EAR

3. EXTERNAL EAREXTERNAL EAR
AURICLE OR PINNA
EXTERNAL AUDITORY
CANAL

4. PINNAPINNA
Single 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

5. 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.

6. 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

7. 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

8. 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

10. EXTERNAL AUDITORY CANALEXTERNAL AUDITORY CANAL
Extends from bottom of concha to tympanic
membrane
24 mm (along post wall)
not a straight tube
outer part(cartilaginous) directed upwards,
backwards & medially
inner part (bony) directed downwards,
forwards & medially
pinna pulled upwards, backwards &
laterally(make it straight)

11. EXTERNAL AUDITORY CANALEXTERNAL AUDITORY CANAL
CARTILAGINOUS
BONY

12. CARTILAGINOUS PARTCARTILAGINOUS PART
Outer 1/3
rd
& 8mm canal
Continuation 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

13. 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 1/3
rd
of canal

14. BONY PARTBONY PART
Inner 2/3
rd
& 16mm
Skin lining the bony canal in thin & continuous
over the tympanic membrane
Devoid of skin appendages(Hair and
ceremonious Glands
About 6mm lateral to tympanic membrane ,
bony meatus presents as narrowing called
ISTHMUS
Foreign body lodged medial to isthmus, get
impacted & are difficulty to remove

15. 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)

16. NERVE SUPPLY - EACNERVE SUPPLY - EAC
Auriculo 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

17. TYMPANIC MEMBRANETYMPANIC MEMBRANE
Forms partition between
EAC & middle ear
Obliquely set – 45deg
with floor of EAC
Posteriosuperior part
more lateral than
Anterioinferior part
9-10 mm tall
8-9 mm wide
0.1 mm thick

19. PARS TENSA
PARS FLACCIDA (SHRAPNEL’S
MEMBRANE)
TYMPANIC MEMBRANETYMPANIC MEMBRANE

20. 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

21. PARS FLACIDAPARS FLACIDA
Situated above lateral process of malleus
between the notch of rivinus & anterior &
posterior malleolar fold
Appear slightly Pinkish

22. LAYERS OF TYMPANIC MEMBRANELAYERS OF TYMPANIC MEMBRANE
Outer 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)

23. NERVE SUPPLY - TMNERVE SUPPLY - TM
AURICULO 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

24. ANATOMY OF EAR
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