Transcript ANATOMY OF THE EAR

Anatomy of the External
Ear
Dr. Supreet Singh Nayyar, AFMC
MS (ENT)
For more presentations, visit www.nayyarENT.com
Parts of the Ear
• External Ear
• Middle Ear (Cleft)
• Inner Ear
ANATOMY OF THE EAR
• Hearing is a primitive sense and is essential in all
animals
• Well developed and well protected
• It needs a sound source, conducting mechanism,
end organ and a central processor
Pinna
Parts
EAC
 External ear
 Middle ear
 Inner ear
TM
EXTERNAL EAR
Auricle (Pinna)
• Projects from the side of the head (shape size and
angle varies)
• Shape maintained by a yellow elastic cartilage
(one piece of cartilage forming pinna and external
part of EAC, except lobule)
• Covered with skin
• Several elevations and depressions
AURICLE
AURICULAR CARTILAGE
Auricle (Pinna)
Blood Supply
 Cranial surface
- Posterior auricular A
 Lat surface - Anterior auricular A (Sup temp A)
Nerve supply




Greater auricular (C2-3)
Lesser occipital (C2)
Auricular branch of Facial (Concha)
Auriculotemporal N
Lymphatic drainage
Mastoid tip
Pre-auricular
Deep cervical
PINNA NERVE SUPPLY
PINNA NERVE SUPPLY
EXTERNAL AUDITORY CANAL
• From bottom of concha to TM
• 24 mm along with post wall
• Lateral cartilaginous and medial bony part
Cartilage part
 Outer 1/3 (8 mm), deficient at Incisura terminalis (root of
helix and tragus)
 Skin is thick with hairs and sebaceous and ceruminous
glands (Apo-pilo-sebaceous Units)
 Fissures in ant wall ‘fissures of Santorini’
Bony Part
 Medial 2/3 (16 mm)
 Two constrictions (Isthmus 5 mm lateral to TM)
 Ant recess sump for discharge
 Skin has no subdermal layer, firmly attached to
periosteum
EAC
EXTERNAL AUDITORY CANAL
 Has ceruminous glands in lateral 1/3rd
 Deficient in children
Blood Supply
 Ext Carotid system (Sup temporal, Maxillary, Post auricular)
Nerve supply
 Ant half Auriculotemporal N, post half by Arnold’s N (X)
Relations




Ant
Post
Sup
Inf
-
TMJ
Mastoid
Middle fossa
Parotid gland
CERUMINOUS GLANDS
• Simple, tubular, coiled structure having
myoepithelium
• Secretions expressed into root canal
• Watery white secretion initially dries up and gets
oxidised and becomes sticky and dark in colour
• Modified sweat glands and react to same stimuli
as other apocrine glands. Ad, fever, stress ↑
secretions
Ceruminous and sebaceous
glands
WAX
• Mixture of secretions of ceruminous and sebaceous
glands
• Two types dry and wet
• Dry wax – yellowish or grey, dry and white
• Wet wax – yellowish brown, wet and sticky
• Contains amino acids, fatty acids, lysozymes and
immunoglobulins.
• Has a bactericidal activity
• Migrates outside but may get impacted
Tympanic Membrane
• The external ear canal
describes an S - like
pathway
from
the
entrance to the TM.
• The TM separates the
external ear canal from
the middle-ear cavity and
is inserted at an angle of
approximately 55°.
Tympanic Membrane
• Separates auditory meatus of external
ear from tympanic cavity of middle ear.
• Composed of four strata arranged in 3
general layers
o Outermost (cutaneous - ectoderm) very thin
skin
o Middle (connective tissue - mesoderm)
• Radiate (radiatum) fibroelastic connective tissue
• Circular (circulare) fibroelastic connective tissue
• In the Pars flaccida the radiate and circular layers
are extremely thin and considered absent
• Annulus fibrosus
o Innermost (mucosa - endoderm) mucous
membrane, with low cuboidal epithelium
continuous with lining of tympanic cavity.
TYMPANIC MEMBRANE
• Landmarks

Cone of Light

Umbo

Handle of Malleus

Lat Process of Malleus

A & P Malleolar Fold

+/- Incus shadow

Annulus
TYMPANIC MEMBRANE ON
OTOSCOPY
Tympanic Membrane - Quadrants
APPLIED ANATOMY
1.
2.
3.
4.
5.
6.
7.
Lat part of EAC runs inwards, downwards and
forwards. Ear pulled out, post and laterally
Relatively less subcutaneous tissue makes the
pinna more sensitive to frost bite
Incisura terminalis is used for end-aural incision
Referred otalgia
Imp donor of cartilage and fat
Isthmus holds the FB
Vagus stimulation to increase appetite
APPLIED ANATOMY
8.
Sagging of deep postero superior wall – Ac
mastoiditis
9. Furuncles only in lat part, very painful
10. Persistent cough by impacted wax
11. Cymba conchae direct relation to suprameatal
triangle
12. Skin has unique quality of migrating laterally
Thank You
for more presentations,
visit www.nayyarENT.com