The document describes the anatomy and structures of the external ear, external auditory canal, tympanic membrane, and middle ear. It details the parts of the ear, including the pinna, external auditory canal, tympanic membrane, as well as the blood supply, nerve supply, functions of structures like the cerumen glands. The tympanic membrane separates the external ear canal from the middle ear cavity and is composed of layers of connective tissue and skin.

1. Dr. Supreet Singh Nayyar, AFMC
MS (ENT)

2.  External Ear
 Middle Ear (Cleft)
 Inner Ear

3.  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
Parts Pinna
 External ear EAC
 Middle ear TM
 Inner ear

5.  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

8. 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

11.  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

13. 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 - TMJ
 Post - Mastoid
 Sup - Middle fossa
 Inf - Parotid gland

14.  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

16.  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

17.  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°.

18.  Separates auditory meatus of external
ear from tympanic cavity of middle ear.
 Composed of four strata arranged in 3
general layers
◦ Outermost (cutaneous - ectoderm) very thin
skin
◦ 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
◦ Innermost (mucosa - endoderm) mucous
membrane, with low cuboidal epithelium
continuous with lining of tympanic cavity.

19.  Landmarks
 Cone of Light
 Umbo
 Handle of Malleus
 Lat Process of Malleus
 A & P Malleolar Fold
 +/- Incus shadow
 Annulus

20. TYMPANIC MEMBRANE ON
OTOSCOPY

23. 1. Lat part of EAC runs inwards, downwards and
forwards. Ear pulled out, post and laterally
2. Relatively less subcutaneous tissue makes the
pinna more sensitive to frost bite
3. Incisura terminalis is used for end-aural incision
4. Referred otalgia
5. Imp donor of cartilage and fat
6. Isthmus holds the FB
7. Vagus stimulation to increase appetite

24. 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