ANAT0MY OF EXTERNAL EAR ONLY FOR POST GRADUATES

1. AnatomyandEmbryologyofExternalEar
byDr.AnkitPrakash(PG1)
KIMS,BHUBANESWAR

2. EMBRYOLOGY OF EAR
• Pharyngeal arches are rod like
thickenings of mesoderm
present in the wall of foregut.
• The pharyngeal arches are six
curved mesodermal thickenings
with each arch having an
ectodermal covering and an
endodermal lining containing a
mesodermal core.

3. EMBRYOLOGY OF EAR
TIMELINE FOR DEVELOPMENT

4. PHARYNGEAL ARCHES

5. PHARYNGEAL ARCHES

6. EMBRYOLOGY OF EAR
• The internal ear is the first part to develop among the
three parts of the ear

7. EMBRYOLOGY OF EAR
• The dorsal part of 1st pharyngeal pouch and part of 2nd pharyngeal pouch (endoderm) form tubotympanic
recess that gives rise to pharyngotympanic tube and middle ear cavity.
• The ear ossicles and muscles of middle ear develop from mesoderm of 1st and 2nd arches.
• The external acoustic meatus develops from ectodermal cleft of 1st arch.
• The auricle develops from mesodermal thickenings around 1st ectodermal cleft.

8. DEVELOPMENT OF PINNA
• Around 6th week of intrauterine life
• Develops from six hillocks or tubercles of
his around 1st pharyngeal cleft
• 1st tubercle from- 1st branchial arch
• Rest 5 tubercle from- 2nd branchial arch

9. DEVELOPMENT OF EAC
• Develops around 1st branchial
cleft as an invagination into
funnel shaped pit to form
primary EAC .
• Subsequent medial growth with
solid core of ectoderm leads to
formation of a meatal plate
called secondary EAC.
• Between 8-10th week of iul solid
core of epithelium undergoes
canalization to form definite EAC

10. CONGENITAL ANOMALIES OF EXTERNAL EAR
PRE AURICULAR SINUS-DUE
TO INCOMPLETE FUSION OF
HILLOCKS OF HIS DURING
EMBRYOGENIC PERIOD
PREAURICULAR
APPENDAGES
MICROTIA
HELICAL RIM
DEFORMITY

11. CONGENITAL ANOMALIES OF EXTERNAL EAR
ANOTIA BAT EAR-PRESENTS AS
ABNORMALLY PROTRUDING
EAR.THE OVERPROJECTION
EXCEEDS 9 MM FROM MASTOID
DARWINS TUBERCLE-A SMALL
PROMINANCE IN POSTERIOR ASPECT
OF HELIX
STAHL’S EAR

12. CONGENITAL ANOMALIES OF EXTERNAL EAR
COLLAURAL FISTULA
IT IS ANNOMALY OF 1st BRANCHIAL CLEFT
ONE OPENING IN EAC AND OTHEN OPENING IN
UPPER PART OF ANT.BORDER OF SCM
EAC ATRESIA

13. CONGENITAL ANOMALIES OF EXTERNAL EAR

15. PARTS OF EAR
1.EXTERNAL EAR-
• Auricle/pinna
• External auditory canal
• Tympanic membrane
2.MIDDLE EAR-
• Ear ossicles-malleus
Incus
Stapes
• Middle ear cleft
3.INNER EAR-
• Oval window
• Round window
• Cochlea
• Vestibule
• Semi circular canals

16. EXTERNAL EAR
PINNA-
• Lobule is formed by fibrous and adipose tissue covered by skin
• Skin on lateral surface is closely adhered to perichondrium as compared to skin of medial
side.
• Epithelium –keratinising squamous epithelium
Pinna is source of graft in ear and nose surgery.
• Graft in rhinoplasty- conchal cartilage are used to correct depressed nasal bridge ,skin
and cartilage are used for defect in ala of nose.
• Graft in tympanoplasty-tragal and conchal cartilage,perichondrium and fat from lobule
are used .

17. PARTS OF PINNA
HELIX
In some pinna there is elevations present which is called
as Darwin’s tubercle
ANTI HELIX
 It is parallel to helix
 TRIANGULAR FOSSA –Present between ant and
posterior crus of anti helix
 SCAPHOID FOSSA-Present between upper part of
helix and anti helix

18. PARTS OF PINNA
TRAGUS
It is triangular prominance pointing posteriorly
Lies below crus of helix
TRAGAL TENDERNESS-It is seen in infection of external
auditory canal such as otitits externa,otomycosis of external
ear.
ANTI TRAGUS-
Parallel to tragus
• Tragus and anti tragus are seperated by intertragic notch
• Thick hairs develop in this area in older age male
CONCHAL CARTILAGE
It mainly forms a concavity which is known as concha
Divided by crus of helix into
• Cymba concha(above)
• Cavum concha(below)
In adults we can elicit mastoid tenderness by pressing on
cymba concha(mastoid antrum lies below cymba concha)

19. PARTS OF PINNA
INCISURA TERMINALIS-
• It is present between crus of helix and tragus
• It is devoid of cartilage (presence of dense
fibrous tissue band )-so there is decreased
chance of perichondritis in this area
• Lempert’s endaural incision is given in this
area –it will not cut cartilage in this area in
surgery of eac or mastoid
INCISIONS IN PINNA-

20. BOXERS EAR-
Cartilage necrosis due to stripping of
perichondrium from cartilage following
trauma
PSEUDOCYST-Cystic collection of fluid
between cartilage of pinna
DEFORMITIES OF PINNA

21. DEFORMITIES OF PINNA
KELOID PERICHONDRITIS

22. AURICLE/PINNA
Cartilage of pinna is connected to temporal bone by
• 2 extrinsic ligaments- Anterior ligament
Posterior ligament
• Many intrinsic ligament
Anterior ligament-from tragus and crus of helix to root of zygomatic arch
Posterior ligament-from medial surface of concha to lateral surface of mastoid prominance.

23. AURICLE/PINNA
Muscles-
3 extrinsic
• Auricularis anterior
• Auricularis posterior
• Auricularis superior
These muscles radiate from auricle
to gets inserted into epicranial
aponeurosis.
6 intrinsic- they are not useful
Auricularis superior
Auricularis anterior
Auricularis posterior

24. AURICLE/PINNA
Blood supply of auricle
• Posterior auricular branch of ECA-supplies medial surface
of pinna,concha,helix(middle and lower
portion),antihelix(lower part)
• Anterior auricular branch of superficial temporal artery –
supplies upper portion of helix ,anti helix,triangular fossa
and lobule
Lymphatic drainage-
From posterior surface-to lymph node of mastoid tip
From tragus and upper part of anterior surface-preauricular
nodes
Rest-upper deep cervical nodes

25. AURICLE/PINNA
Nerve supply of auricle
• Auriculotemporal nerve
• Great auricular nerve
• AURICULAR BRANCH OF vagus(xth NERVE)
• Facial nerve
• Lesser occipital nerve
So in herpes zoster oticus lesions are seen
along distribution of facial nerve that is
conchal region and post auricular regions.

26. PARTS OF EAC
It develops from 1st pharyngeal cleft
It is s shaped tube which extends from bottom of conchal cartilage till tympanic membrane
2 parts
CARTILAGENOUS -8 mm IN LENGTH AND IS LATERAL 1/3rd
Lateral border is in continuation with aural cartilage
Medial border is attached to rim of bony canal by fibrous band
Bony- 16 mm in length and is medial 2/3rd

27. EAC
Cartilagenous part is upward backward and medially
Bony part is downward forward and medially
So to visualise tympainic membrane we have to pull pinna upward
backward and laterally(EAC becomes straight and TM is visualised)
In neonates there is virtually no bony external meatus as tympanic
membrane is not yet developed and tympanic membrane is more
horizontaly placed so pinna must be pulled downward and
backward for best possible visualization of tympanic membrane

28. EAC
Cartilagenous eac
• Hairs are present only in cartilagenous part
• Ceruminous gland which is a modified apocrine sweat
gland opens into root of hair and is affected by
adrenergic drugs,emotions,fever leading to increased
production of cerumen.
• Pilosebaceous gland is also present which secrete
sebum.
Furunculosis-
Infection of single hair follicle.
Oedema and inflammation in cartilaginous part of EAC .
Main causative agent is S.Aureus.

29. EAC
Fissure of santorini –
• These are defects which are 2 in number
• Present in floor in cartilagenous part of EAC
• Infection and neoplasm can spread to and from
this area to parotid and mastoid
FISSURES OF
SANTORINI

30. EAC
Bony EAC-
Extends till tympanic membrane laterally
Mainly formed from temporal bone
Roof
• Squamous part of temporal bone
• Petrous part of temporal bone
Inferior part-
• From tympanic part of temporal bone
2 suture lines are present
• Tympanosquamous suture-present anteriorly
• Tympanomastoid suture-present posteriorly
Very thin skin and no hair follicles are present in this area.

31. EAC
Constrictions present in eac
Isthmus-
It is narrowest part of eac
Situated 5 mm lateral from tympanic membrane
Most common site for lodgement of foreign body in ear
Foramen of huschke-
Present in anteroinferior part
Infection from parotid can go to and from mastoid
So in case of acute mastoiditis there is sagging of posterosuperior canal wall.
Anterior recess-
Present between isthmus and tympanic membrane
Most common site for collection of discharge in EAC
ANTERIOR
RECESS

32. EAC
Relation of bony eac-
1.Superior-middle cranial fossa
2.Inferior-parotid gland
3.Posterior-mastoid antrum
4.Anterior-temporomendibular joint
5.Medial-tympanic membrane
6.Lateral-cartilagenous part of eac

33. EAC
• It is lined by keratinizing squamous epithelium
• There is oblique growth of epidermis of canal and pars Flaccida
So surface layers migrate towards external opening of canal
• If there is failure of migration of it leads to building up of shed keratin in canal known as keratosis obturans
• If this skin migrates to middle ear cleft-it may cause cholesteatoma

34. EAC
Wax
It is collection of dead skin + sebum+ cerumen
It is of 2 types
Dry wax – it lacks cerumen
Yellowish in color
Seen mainly in Asian population
Wet wax- cerumen is present
Brownish and sticky
Seen in European population

35. EAC
Blood supply of EAC-
• External carotid artery
• Auricular branch of superficial temporal artery-supplies roof and anterior wall
• Deep auricular branch of maxillary artery-supplies anterior part
• Auricular branch of posterior auricular artery –supplies posterior part
Venous drainage
• External jugular vein
• Maxillary vein
• Pterygoid plexus

36. EAC
Nerve supply
• Auriculotemporal nerve-anterior wall and roof-branch of V3
• Auricular branch of vagus –posterior wall and floor
• Auricular branch of vagus-also gives sensory supply of VIIth nerve in posterior wall
Coughing during syringing-due to stimulation of arnold’s nerve(branch of Xth nerve)
Hitzelberger sign-Hypostehesia of posterior meatal wall (sensory supply of posterior meatal wall is
affected)
Seen in vestibular Schwanoma

37. TYMPANIC MEMBRANE
• Oval in shape
• Pearly white in color
• Lying at angle of 55 degree with
floor of meatus
• Forms lateral boundary of
middle ear cavity
• 4 quadrants
• 3 layers- in upper part it has only
2 layers
• 2 parts
9-10mm
diameter
8-9mm
diameter

38. TYMPANIC MEMBRANE
3 layers of tympanic membrane-
3 layers-
• Outer-epithelial-it is in continuation with skin of external meatus
• Inner-mucosal layer-it is in continuation with lining of tympanic cavity
• Middle-fibrous-it has lamina propria
Pars tensa have radially oriented fibers in outer layer and circular, parabolic and
transverse fibers in deeper layers.
Pars flaccida have less marked lamina propria and orientation of fibers are
random.

39. TYMPANIC MEMBRANE
• Most of circumference is thickened to form fibrocartilaginous ring c/a tympanic annulus, sitting in the
tympanic sulcus
• Sulcus does not extend to notch of rivinus which is present in roof of meatus formed by squamous
part of temporal bone.
• Pars Flaccida is present above malleolar fold within notch of rivinus and it does not have tympanic
annulus at its margins.

40. TYMPANIC MEMBRANE
Blood supply of tympanic membrane-
Outer surface by –
• Deep auricular branch of maxillary artery coming
from external auditory meatus
Inner surface by-
• The anterior tympanic branches of the maxillary
artery
• The stylomastoid branch of the posterior auricular
artery and probably from the middle meningeal
artery.
Venous drainage-
• Outer surface drains into external jugular vein
• Inner surface drains into transverse sinus and
venous plexus located around eustachian tube

41. TYMPANIC MEMBRANE
Nerve supply
Latral surface of tm-
• Branches of auriculotemporal nerve
• Auricular branch of vagus
Medial surface of tm-
• Tympanic branch of glossopharyngeal nerve

42. THANK YOU
Reference- Scott Brown