The document discusses the anatomy and embryology of the external ear. It describes the development of the pinna, external auditory canal, and tympanic membrane from pharyngeal arches. The pinna is made of elastic cartilage covered by skin. The external auditory canal has cartilaginous and bony portions. The tympanic membrane separates the external ear from the middle ear. Blood supply, nerve innervation and clinical applications are also summarized.

1. Presented by
Dr Sanjita Dash(jr 1)
Dept of ent
External ear

2. Parts of ear
Different parts of ear
•External ear
•Middle ear
•Inner ear

3. External ear
• Auricle /pinna
• External auditory canal

4. Embryology of external ear
The external auditory meatus arises from the 1st
pharyngeal cleft.it begins as an invagination of
ectoderm between the first and second pharyngeal
arches that extend inwards towards developing
middle ear structures.
At wk of 5th embryonic development this
ectodermal diverticulum extends towards the
pharynx and contain proliferating ectodermal cells
that form a meatal plug that fills the entire lumen.
At 10th wk the bottom of meatal plug expands
circumferentially to create a disc like structure

5. • By 13th wk this disc like plug comes into contact
with primordial malleus medially,contributing to
the future formation of TM
• 15th wk-disc like plug splits disk-like plug splits,
leaving behind a thin ectodermal cell layer of the
immature tym membrane
• External auditory meatus is completely patent and
expands to its complete form by 18th wk

6. • By end of 4th wk of development the auricle
develops from 6 mesenchymal proliferaions known
as hillocks derived from 1st and 2nd pharyngeal
arches that surrounds 1st pharyngeal cleft
• There are 3 auricular hillocks on each side of
external meatus that eventuualy fuse to form
auricle
• First 3 auricular hillocks fuse -tragus,helix and
cymba concha
• Last 3 auricular hillocks arise from 2nd pharyngeal
arch and gives-concha;antihelix,antitragus

7. Pinna
• Single piece of yellow
elastic cartilage covered
with perichondrium
and skin(except lobule
and outer part of eac)
• Attached to side of skull
by ligaments and
muscle(supplied by
facial nerve),muscles
are not well developed
in human

8. • Cartilage is connected to temporal bone by 2
extrinsic ligaments –anterior and posterior ligament
• Ant lig.-tragus and cartilaginous soine on ant rim of
crus of helix to root of zygomatic arch
• Post lig.-medial surface of concha to lateral surface
of mastoid prominence
• Intrinsic ligament s connect various part of
cartilaginous pinn

9. • Tragal cartilage,perichondrium from
tragus,concha,fat from lobule-reconstruction
surgery for middle ear
• Conchal cartilage-correct depressed nasal bridge
• Composite graft of skin and cartilage from pinna-
repair defects of nasal ala
• Cymba concha –landmark for suprameatal triangle
(macewns triangle)1.5 cm from tragus anterior and
inferiorly lies the facial nerve ..tragus acts as
surgical landmark

10. Cont…
• 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-incision made on this area
will not cut through the cartilage in surgery of EAC
or mastoid

11. Sensory innervation of pinna
nerve derivation Region supplied
Greater auricular C2,C3 Medial surface and
posterior portion of
lateral surface
Lesser occipital C2,c3 Superior portion of
medial surface
auricular Vagus nerve Concha and
antihelix,some supply
medial surface(eminetia
concha)
auriculotemporal Mandibular neve Tragus,crus of
helix,adjacent helix
Facial nerve Small region of root of
comcha

13. Artery supply of pinna
• It has end arterial supply hence
while giving local one must keep
in mind to administer local
anesthetic sans adrenaline
• Nerve block;
• Plester injection technique-post
auricular injection(1behind the
ear+4 in canal)
• Fisch injection technique-(2+1)
• Jacobson nerve anesthesized by
placing cotton ball or gel foam
soaked with 1%lidocaine or
4%tetracaine.

14. Source :

15. Lymphatic drainage of pinna
• Medial surface –LNat
mastoid
tip(retroauricular ln)
• Tragus and upper part
of anterior surface-pre
auricular lymph node
• Rest of auricle –infra
auricular LN
superficial cervical LN
upper deep cervical LN

16. External auditory cannal
• Extends from bottom of
concha to TM
• S shaped cnnal combination of
cartilaginous and bony
component
• 24 mm(along post wall)
• Not a straight tube
• Outr part-cartilaginous –
upward,backward,medially
• Inner part-bony-
downward,forward,medially
• Pinna pulled
upward,backward and
laterally (make straight)

17. • But in children eac directed more horizontally so
we pull pinna downward and backward

18. Cartilaginous part
• Outer one third -8mm
• Continuation of yellow elastic cartilage which forms
the frame work of pinna
• Fissure of Santorini-through it parotid or supf
mastoid infection can appear in cranial or vice versa
• Skin covering cartilaginous canal is thickand contain
appendages like-1.ceruminous gland (modf sweat
gland)2.pilosebaceous gland 3.hair –only confined
to outr cannal so furuncle seen only in outer one
third of cannal

19. Bony part
• Inner two third -16mm
• Skin lining here is thin and continuous with tm
• Devoid of skin appendages(hair and gland)
• Abt 6mm lateral to tm bony meatus narrows k/a
isthmus…fb lodged medial to isthmus get impacted
and difficult to remove
• Antero inferior part of deep meatus ,beyond the
isthmus presnt as recess-ANTERIOR RECESS which
act as a cesspool for discharge and debris

20. • Antero inferior part of bony canal present as a
deficiency in children upto 4 or sometimes in adults
permits infection to and from parotid(FORAMEN OF
HUSCHKE0

21. Blood supply of eac
• Auricular br of superficial temporal artry-roof of
anterior portion of cannal
• Deep auricular br. Of 1st prt of maxillary artery-ant
meatal wall skin and epi. Of outer surface of tm
• Auricular br of post auricular artery-post portion of
cannal
• Veins drain to ejv ,maxillary veins and pterygoid
plexus
• Lymphatic drainage follows that of pinnq

22. Nerve supply of eac
• Auriculotemporal
nerve(v3)-ant wall and
roof
• Auricular br of vagus-
post wall and floor
• Post wall of auditory
cannal also recives
sensory fibres of cn 7
through auricular
branch of vagus

24. Tympanic membrane
• Forms partition between EAC and middle ear.
• Obliquely set-45 deg with floor of eac
• Posterosuperior part more lateral than
anterioinferior part
• 9-10mm tall
• 8-9mm wide
• 0.1mm thick
• Parts of tm-pars tens and pars flaccida(shrapnels
membrane)

26. Pars 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 level
of tip of malleus-UMBO
• Bright CONE OF LIGHT seen radiating from the tip
of malleus to periphery in anterioinferior quadrant

27. Pars flacida
• Situated above lateral process of malleus between
the notch of rivinus and anterior and post malleolar
fold.
• Annuls deficient superiorly in pars flaccida and is
called notch of rivinus
• Appears slightly pinkish

28. Clinical application-tm perforation
and their impact on hearing loss
• The dominant mech. Of tm perforation on hearing
loss is a reduction in the pressure difference across
both side of tm.
• Hearing loss is largest at the lowest frequency and
decrease with increasing frequency
• Hearing loss inc. with size of perforation
• Hearing loss does not depend on location of
perforation

29. Bood supply of TM
OUTER SURFACE-circumferential,manubrial and
radial br. From deep auricular br of maxillary artery
INNER SURFACE-1.anterior tympanic branch of
maxillary artery
2.Post tympanic br of pst auricular artery

30. NERVE SUPPLY OF TM
• Auriculotemporal nerve –
supplies ant half of lateral
surface
• Auricular br of vagus-
supplies post half of
lateral surface
• Tympanic br of
glossopharyngeal nerve
supplies medial surface
• Vascular innervation are
relatively sparce in the
middle part of post. Half
of tm

31. histology
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,parabolic

32. Tm retraction pockets
• Pars flaccida retraction pocket-this mc area of tm
retraction pocket because it is the weakest part of
tm.2 reasons behind this-
• 1.sparse amount of unorganized fibres in its lamina
propria
• 2.direct insertion of skin of p.flaccida on scutum in
the absence of combination of annulus sulcus
,which act like a ligament stabilizing the insertion of
the tm to the surrounding bone

33. Pars tensa retraction pockets
This is mc in postero superior part3 reasons
1.This part of tm is more vasularised and thus more
vulnerable to inflammationCollagenase secretion and
destruction of collagen fibres.leads to this part of tm
atrophic and prone to retraction in middle ear
negative presuure
2.Middle fibrous layer of postero superior part lacks
a well developed circular fibrous layer
3.Weak annulus insertion on the tympanic ring bcoz
of shallow sulcus at this level

34. Temporal bone
• Parts-
• 1.tympanic part
• 2mastoid process
• 3.squamous part
• 4.petrous part

35. • Squamous bone-flattend region that forms laterl
portion of the skull and is the origion for temporalis
muscle.the zygomatic process extends anteriorly from
the squamous bone.
• ty,mpanic bone-forms the floor,anterior and inferior
wall of the bony portion of eac
• Styloid bone-a slender process of variable lenghth that
extends in ananterior- inferior direction and serves as
the attachment for the
stylohyoid,styloglossus,stylopharyngeus muscles
-

36. • Mastoid bone-immediately infront of the ext aud
meatus is glenoid(mandibular fossa)where the
condyle of mandible articulates

37. Temporal bone fissures
• 1.the petro squamous fissure-open directly into
mastoid anturum
• 2.tympano mastoid fissure-auricular br of vagus nerve-
Arnold nerve emerge through tympano mastoid suture
• 3.tympanosquamous fissure-it is seen in antero
superior part of eac and continue medially into the
petrotympanic and petrosquamous fissure
• 4.petrotymapnic fissure(glaserian fissure)-b/w
tympanic bone and mandibular fossa –transmit chorda
tympani,ant tympanic art.,ant. Malleal ligament

38. Clinical pearl-
• In trauma these normal fissures especially if
evident may be misinterpreted as temporal bone
fractures
• The petro squamous fissure may remain open until
age the age of 20 yr,provide route of spread of
infection from middle ear into intracranial cavity

40. Temporal bone surfaces-lateral
surface
• Mastoid process-attachment of scm muscle lateraly
and podt belly of diagastric muscle medially
• Zygomatic process-mandibular /glenoid fossa-for
condyle of mandible.
• Temporal line /suprameatal crest-attachment of
temporal muscle.landmark for level of middle
cranial fossa dura
• Suprameatal mac ewens triangle-b/w post sup wall
of eac and temporal line-correspond medially to
antrum

41. The scutum-bony spur formed at junction of lateral
wall of middle ear cavity and sup wall of eac
Henles spine-post sup edge of eac –aditus and
antrum laterlly

42. Posterior surface
• Int aud meatus
• Endolymphatic sac
• Retrosigmoid approach-for tretmnt of pathologies
of post surface of temporal bone and cp angle.this
allow adequate exposure of cp angle and iac.it
allows resection of tumor of diff sizes with
possibility of preserving facial and cochlear
function

44. Superior surface
• Tegmen tympani
• Petrous bone(maj)+squamous none(minor)
• Eminentia arcuate-correspond to wall of sup scc
• Greater superficial petrosal nerve and geniculate
ganglion
• The petrous apex

45. Surgical implication
• The geniculate ganglion could be dehiscent in 15-
20% cses .in these cases risk of injury to facial nerve
during middle cranial fossa aprocah is v high while
elevating duramatter from sup surface of temporal
bone.

46. Middle cranial fossa approach
• It is an extradural acess route to approach sup
surface of temporal bone and iac.
• Common neurotologic indication for middle cranial
fossa approach are facial n. decompression,sup scc
dehiscence repair,removal of large tegmen defects
and meningoencephalocele,removal of small
intracanalicular acoustic neuroma.
• Lack of definitive landmarks on the sup surface of
temporal bone marks this approach tech. difficult.

47. • 2 imp landmarks GSPN and eminentia arcuate .

48. Anatomy of middle ear
• Consists of-
• Auditory tube
• Tympanic cavity
• Aditus
• Mastoid air cells

49. Embryology of middle ear
• The et tube,tympanic cavity,attic,mastoid air cells
develop from the endoderm of tubotympanic
recess which arises from the first pharyngeal pouch
• Malleus and incus are derived from mesoderm of
1st arch while stapes develop from the second arch
except its foot plate and annular ligament which
are derived from otic capsule

50. Clinical pearl-congenital
cholesteatoma
• It consist of residual squamous inclusion cysts that
arise from epi.rests in middle ear
• These epi. Rests are normally seen during fetal
development and disappear by 3rd trimester
• Failed involution –congenital cholesteatoma

51. Eustachian tube
• Aka pharyngotympanic tube is a narrow
fibrocartilaginous duct that connects middle ear to
the nasopharynx
• The proper function of eustachain tube is critical
for optimization of middle ear sound transmission
and health maintainance
• Structurally the ET is compromised of
osseous,junctional and cartilaginous areas from
lateral to medial

52. Inferior surface

53. Fish infratemporal fossa
approach(itf)
• Type a approach-removal of tumors of jugular foramen
involving vertical segment of petrous int carotid
art.,class c and d glomus tumors.
• Type b approach-acess to clivus and petrous apex and
and applicable to glomus tumors involving horizontal
petrous carotid artery,clival chordoma and congenital
cholesteatoma of petrous apex.
• Type c approach-anterior extension of type b and
allows exposure of parasellar
region,nasopharynx,pterygomaxillary fossa,Eustachian
tube.used primarily for for extensive JNA and post
radiation failure sq cell ca.

54. • Normally a closed structure et tube opens in
response to movement of mandible and
pharynx,such as chewing or swallowing.
• It serves imp role in middle ear fumction including
ventilation and facilitation of secretion clearance
which serves to protect middle ear pathogen
• Normal opening of the tube also helps to equalize
pressure between the middle ear and atmospheric
pressure in nasopharynx

55. • Lumen of et tube-ciliated pseudostratified
columnar epi.(clearance of secretion into
nasopharynx)
• The tensor veli palatini contracts the anterolateral
wall to cause dilation and opening of distal et tube
• Contraction of levator veli paltini –elevation of soft
palate and medial rotation of cartilaginous lamina
• When these muscles contract simultaneously
through swallowing or yawning air can pass
through the tube to equilibrate presuure in middle
ear with atmospheric presuure

56. • 2 other muscles associated with et tube have not
been shown to have a significant role in opening
the lumen include the tensor tympani and
salpingopharyngeus muscle

57. 6 surfaces of middle ear
• Medial wall
• Lateral wall
• Posterior wall
• Anterior wall
• Roof
• floor

58. Lateral wall
• Partly bony and partly membranous
• Central portion-tm and incomplete tympanic ring
to which tm Is attache
• Above tm bony wall –attic outer wall
• 1.