5. PINNA
• Around 6th week of IUL
•Developsfrom six hillocksorTUBERCLES OF HIS around 1st
pharyngeal cleft .
•1ST Tubercle- 1st branchial arch
•REST – 2nd branchial arch
9. ⚫PRE-AURICULAR SINUS- Defective fusion of tubercles .
⚫ ANOTIA – Failureof developmentof hillocks .
⚫BAT EAR DEFORMITY – Defectivedevelopmentof 4th
tuberclecausing absenceof antihelix .
⚫CRYPTOTIA (hidden or pocket ear) - an abnormality
of the auricle where the upper pole is buried beneath the
temporal skin. It can be restored to a more normal form
by a sequence of surgical procedures that involve the use
of splints tocreate a new scaphoid fossa and grafts or local
flaps to release the cartilage from the side of the head.
⚫MICROTIA (diminutive ear)- is usually an isolated
congenital abnormality, but is sometimes associated with
recognized syndromes, e.g. fetal alcohol syndrome,
maternal diabetic syndrome, thalidomide and
isotretinoin exposure.
10. ⚫POLYOTIA (mirror ear) - is caused by persistence of pre-
auricular tissue that would normally be included in the
pinna, but instead lies in front of the tragus in the
posterior aspectof the cheek.
⚫STAHL’S BAR(Satiro's ears) - helix is flattened and the
upper crus of the antihelix is duplicated, producing a ridge
of cartilage running from the antihelix to the rim of the
helix.
This causes a pointing of the ear and a reversal of the
normal concavity of the scaphoid fossa. Occasionally, the
upper part of the pinna flops over to produce an
appearance known as ‘lop ear
12. EXTERNAL AUDITORY CANAL
⚫Develops around the 1st branchial cleft as an
invagination into funnel shaped pit to form primary
EAC.
⚫ Subsequent medial growth with solid coreof ectoderm
leads to formation of a meatal plate called secondary
EAC.
⚫Between 8th-10th week of IUL solid coreof epithelium
undergoescanalization form in definitive EAC .
13. ⚫Develops from surface ectoderm covering the dorsal end
of 1st pharyngeal groove .
⚫Meatus deepens by proliferation of its ectoderm .
⚫Anteriorly placed bud of epithelial cellsexpand vertically
to form the skin which will cover the future TM.
⚫Clumps of cells then opens up as a slit to form the canal
lumen and produce pars tensa & deep external canal
epithelium .
21. ⚫ Cartilage – avascular , derives nutrients from perichondrium .
⚫ 2 LIGAMENTS –
- Anterior ligament
- Posteriorligament
⚫ MUSCLES –
- EXTRINSIC – Auricularis anterior ,posterior, superior (connect
theauricle to the skull and scalpand move theauricleasawhole)
- INTRINSIC - connect thedifferentpartsof theauricle
22. IMPORTANCE
⚫ INCISURA TERMINALIS- This area is devoid of cartilage , can
be used for giving incision for procedures in ear to avoid post-
op perichondritis .
⚫ LATERAL SURFACE – Skin is firmly adherent to
perichondrium ; so more prone for frost bite.
⚫ MEDIAL SURFACE – More of subcutaneous tissue , skin is
loosely adherent to underlying cartilage ; so cysts like
sebaceous cyst are common .
23. IMPORTANCE
⚫ Stripping the perichondrium from thecartilage, as occurs
following injuries that cause haematoma, can lead to
cartilage necrosis with crumpled up 'boxer's ears'.
⚫Small pieces of skin from the lobule of the pinna are
commonly used for demonstration of lepra bacilli to
confirm thediagnosis of leprosy.
24. BLOOD SUPPLY
ARTERIAL SUPPLY – External carotid artery
⚫Posterior auricularartery
⚫Anterior auricular branches of superficial temporal
artery
⚫Superior auricularartery
VENOUS DRAINAGE- Auricular veins correspond to
the arteries of the auricle. Arteriovenous anastomoses
are numerous in the skin of the auricle and are thought
to be important in the regulation of core temperature
27. LYMPHATIC DRAINAGE
⚫The posterioraspectof the pinnadrains to nodesat
the mastoid tip.
⚫The tragus and upperpartof the pinnadrain into pre-
auricular nodes
⚫The remainderof the pinnadrains toupperdeep
cervical lymph nodes.
30. ⚫ “S” shaped - itsouterpart isdirected upwards, backwards
and medially while its inner part is directed downwards,
forwardsand medially
.
⚫ Therefore, to see the tympanic membrane, the pinna has to
be pulled upwards, backwardsand laterally soas to bring the
two parts in alignment.
⚫ In the neonate, there is virtually no bonyexternal meatusas
the tympanic bone is not yet developed, and the tympanic
membrane is more horizontally placed so that the auricle
must be gentlydrawn downwardsand backwards for the best
view of the tympanic membrane.
31. ⚫ CARTILAGINOUS PART -
Outer 1/3rd of EAC , 8mm
Fissureof santorini
Skin – hair follicles , ceruminous , sebaceousglands
• BONY PART –
Inner 2/3rd of EAC , 16mm
Isthmus
Anterior Recess
Tympanicsulcus
32. ⚫ ISTHMUS – narrowestpartof canal lying medial to junction of
bony & cartilaginousparts nearly 5 mm lateral toTM .
⚫ The roof & posterior wall of EAC are shorter than floor &
anteriorwall ; thus TM fits obliquely in deeperend of thecanal
.
⚫ ANTERIOR RECESS – Anteriorwall of EAC goessharply
forward to the TM to forma blind pouch .
⚫ TYMPANIC SULCUS- medial end of the bonycanal is
marked by agroove, the tympanicsulcus, which is absent
superiorly.
33.
34. IMPORTANCE
• ANTERIOR RECESS- cmn site for foreign body impaction
lodgement.
• FURUNCULOSIS – outercartilaginouscanal
• WAX - impaction (deafness,irritation , itching , otalgiaetc)
• TYMAPANOMASTOIDECTOMY – Incisionat 6 , 12O’ clock
then curvilinear incision to join both to raise a flap
(anteriorly attached with pedicle) which acts as vascular
supply forgraft
35. IMPORTANCE
⚫ Skin lining TM & Bony canal has self cleansing property
due to migration of keratin layerof epithelium from drum
towards cartilaginous portion
Loss of this property – keratosisobturans
⚫Involvement of theear in herpes zosterof thegeniculate
ganglion depends on theconnection between theauricular
branch of thevagusand the facial nervewithin the petrous
temporal bone.
36. IMPORTANCE
⚫Irritation of the auricular branch of the vagus in the external
ear by ear wax or syringing may reflexly produce persistent
cough, vomiting or even death due to sudden cardiac
inhibition. On theother hand, mild stimulationof this nerve
may reflexly produce increased appetite.
⚫Accumulation of wax in theexternal acoustic meatus isoften a
source of excessive itching, although fungal infection and
foreign bodies should be excluded. Troublesome impaction of
large foreign bodies likeseeds, grains, insects iscommon.
38. BLOOD SUPPLY
ARTERIAL SUPPLY – derived from branchesof theexternal
carotid.
⚫ Theauricular branchesof the superficial temporal artery supply
the roof and anteriorportion of thecanal.
⚫ Thedeepauricular branch of the first partof the maxillaryartery
supplies the anterior meatal wall skin and the epithelium of the
outersurfaceof the tympanic membrane.
⚫ Theauricular branchesof the posteriorauricularartery pierce the
cartilage of the auricle and supply the posterior portions of the
canal.
VENOUS DRAINAGE - Theveinsdrain into theexternal jugular
vein, the maxillaryveinsand the pterygoid plexus.
39. NERVE SUPPLY
⚫ Anterior wall and roof: auriculotemporal (V3).
⚫ Posterior wall and floor: auricular branch of vagus (CN
X).
⚫ Posterior wall of the auditory canal also receives sensory
fibres of CN VII through auricular branch of vagus.
⚫IMP- In herpes zoster oticus, lesions are seen in the
distribution of facial nerve, i.e. concha, posterior part of
tympanic membraneand postauricular region.
45. ⚫Peripheral part is thicker & rounded (except in upper
part ) - ANNULUS TYMPANICUS
⚫Annulus isattached at itscircumference to tympanic
sulcus which ends in a notch known as "NOTCH of
RIVINUS" in upperpart.
⚫MALLEOLAR FOLDS - anterior & posterior ; arising
from notch of rivinus to lateral surfaceof malleus .
46. 2 PARTS
PARS TENSA -
⚫ largestpart below malleolarfolds
⚫Containsall 3 layers
⚫Central part is tented inwards at the level of tipof
malleus and is called UMBO
⚫Antero-inferior - most illuminated part
47. PARS FLACCIDA (SHRAPNELL's MEMBRANE) -
⚫Triangulararea above malleolarfolds
⚫Thin , devoid of fibrous tissue & annulus.
⚫It fits into notch of rivinus.
48. Diagram of a coronal section through the external canal and middle ear
at the level of the malleus handle
49. 3 LAYERS
1) OUTER CUTICULAR/EPITHELIAL LAYER -
⚫ It iscontinuouswith skin of EAC
2) MIDDLE FIBROUS LAYER -
⚫ The lamina propria of the pars tensa has radially oriented fibres in the
outer layers and circular, parabolic and transverse fibres in the deeper
layer.
⚫ Thisarrangement probablyaccounts forthecomplex pattern of
tympanic membranedisplacementduring sound stimulation.
⚫ Radial fibres normally mergewith annulus tympanicus
⚫ In the pars flaccida, the lamina propria is less marked and the
orientationof thecollagen fibres seems random.
3) INNER MUCOSAL LAYER -
⚫ It is continuouswith middleear mucosa
