ANATOMY OF THE EAR

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ANATOMY OF THE EAR
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EXTERNAL EAR
Auricle
External Canal
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THE AURICLE
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Absence of antihelix (protruding ear)
Normal
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Perichondritis
Erysipelas
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Endaural incision for external and middle ear
surgery
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Postauricular incision for external and middle
ear surgery
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Blood Supply

• Richly supplied by branches from the external
  carotid

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Cauliflower ear
Hematoma Auris
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The External Auditory Canal
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The External Auditory Canal
Lateral Third
Medial Two Thirds

• Cartilagenous
• Present at birth
• Hair follicles
• Sebacous glands
• Ceruminous glands

• Bony
• Develops after birth

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Skin of outer third of the external canal
Furunclosis
Wax
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ANATOMY OF THE EAR

• External Ear
• Middle Ear Cleft
• Inner Ear

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MIDDLE EAR CLEFT

• Eustachian Tube
• Tympanum (Middle Ear Cavity)
• Mastoid Antrum and Air Cells

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MIDDLE EAR CLEFT

• The Eustachian Tube

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MIDDLE EAR CLEFT

• Eustachian tube
• Tympanic cavity (Middle ear cavity)

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WALLS OF TYMPANIC CAVITY

• Roof
• Floor
• Anterior wall
• Posterior wall
• Lateral wall
• Medial wall

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WALLS OF TYMPANIC CAVITY
Tegmen

• Roof
• Floor

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WALLS OF TYMPANIC CAVITY

• Roof
• Floor
• Anterior wall
• Posterior wall

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WALLS OF TYMPANIC CAVITY

• Roof
• Floor
• Anterior wall
• Posterior wall
• Lateral wall

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Membrana flaccida
Membrana Tensa
Epitympanum(attic)
Mesotympanum
Hypotympanum
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WALLS OF TYMPANIC CAVITY

• Roof
• Floor
• Anterior wall
• Posterior wall
• Lateral wall
• Medial wall

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MIDDLE EAR CLEFT

• Eustachian (Pharyngo-tympanic) Tube
• Tympanic (Middle Ear) Cavity
• Mastoid antrum and air cells

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Mastoid Antrum Air cells
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Mastoid Antrum Air cells
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CONTENTS OF MIDDLE EAR CAVITY

• Air

• Ossicles
• Malleus, Incus, Stapes

• Muscles
• Tensor Tympani Stapedius

• Nerves
• Tympanic Plexus Chorda Tympani

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LINING OF MIDDLE EAR

• Mucous membrane ciliated columnar anteriorly
  and cuboidal or flat elsewhere

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SENSARY SUPPLY OF MIDDLE AND EXTERNAL EAR

• Cervical II III ( great auricular and lessor
  occipital)
• V cranial nerve ( auriculotemporal)
• IX cranial nerve (tympanic or Jacobsons)
• X cranial nerve ( auricular or Arnolds)
• VII cranial nerve

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Referred Earache

• Pain in the ear due to a disease in an area
  supplied by a nerve that also supply the ear.

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Referred Earache

• Cervical II III
• Cervical spondylosis, neck injury etc.
• V cranial nerve
• Dental infections, sinonasal diseases etc.
• IX cranial nerve
• Tonsillitis, post-tonsillectomy, carcinoma etc.
• X cranial nerve
• Tumors of hpopharynx, larynx esophagus

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ANATOMY OF INNER EAR

• Osseous Labyrinth
• Perilymph
• Membranous labyrinth

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The Bony Labyrinth

• Bony Cochlea
• Vestibule
• Bony semicircular canals

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CONTENTS OF THE BONY LABYRINTH

• Perilymph
• Membranous labyrinth
• Cochlear duct
• Saccule and utricle
• Membranous semicircular ducts

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CONTENTS OF MEMBRANOUS LABYRINTH

• Endolymph
• Sensory epithelium
• Cochlea organ of Corti
• Utricle saccule maculae
• Semicircular canals cristae

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INNER EAR SENSORY EPITHELIUM

• Cochlea organ of Corti
• Utricle saccule maculae
• Semicircular canals cristae

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THE VESTIBULO-COCHLEAR NERVE
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CENTRAL CONNECTIONS OF COCHLEAR NERVE
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CENTRAL CONNECTIONS OF VESTIBULAR NERVE
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PHYSIOLOGY OF THE EAR
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FUNCIONS OF THE EXTERNAL EAR

• Auditory functions
• Sound conduction
• Increase sound pressure by the resonance function
• Protection of the middle ear
• Curvature
• Cerumen

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FUNCTIONS OF THE EUSTACHIAN TUBE
Protection
Ventilation
Drainage
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Role of ET Dysfunction

• Main route of infection in AOM (from the
  nasopharynx)
• Obstruction
• Negative middle ear pressure
• Formation of non purulent fluid in the middle ear
  (Otitis Media with Effusion)

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FUNCIONS OF THE MIDDLE EAR

• Conduction of sound
• Transformer mechanism
• Hydraulic action
• Ossicular leverage

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FUNCIONS OF THE MIDDLE EAR

• Conduction of sound
• Transformer mechanism
• Hydraulic action
• Ossicular leverage
• Protection to the inner ear
• stapedial reflex

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FUNCIONS OF THE INNER EAR

• Hearing Function
• Transduction of sound to action potentials

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FUNCIONS OF THE INNER EAR

• Hearing Function
• Transduction of sound to action potentials

• Vestibular Function
• Participate in maintaining body balance

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THE BALANCE SYSTEM
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THE BALANCE SYSTEM
Cerebellum
C. Cortex
BRAIN-STEM
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THE BALANCE SYSTEM
Visual
Proprioceptive
Vestibular
INPUT
Cerebellum
C. Cortex
BRAIN-STEM
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THE BALANCE SYSTEM
Visual
Proprioceptive
Vestibular
INPUT
Cerebellum
C. Cortex
BRAIN-STEM
OUTPUT
Postural muscles
Ocular muscles
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THANK YOU