atsganatomyphysiologyofhteear.pdf

02/07/08
02/07/08 Tinnitus Support Group
Tinnitus Support Group 1
1
Anatomy and Physiology
of the Ear
of the Ear
of the Ear
Eslam Osman, M.D.,F.R.C.S (ORL, H&N Surgery)
Eslam Osman, M.D.,F.R.C.S (ORL, H&N Surgery)

02/07/08
2
Divisions Of The Ear
„
„ External Ear
External Ear
„
„ Middle Ear
Middle Ear
„
„ Inner Ear
Inner Ear
„
„ Central Auditory Nervous System
Central Auditory Nervous System

02/07/08
3

02/07/08
4
Structures of the Outer Ear
Structures of the Outer Ear
Pinna
Pinna
„
„ Collect sound
Collect sound
„
„ Localization
Localization
„
„ Resonator
Resonator
„
„ Protection
Protection

02/07/08
5
External Auditory Canal
External Auditory Canal
„
„ Extends from the pinna to the
Extends from the pinna to the
tympanic membrane
tympanic membrane
„
„ 1 1/2 inch in length
1 1/2 inch in length
„
„ Protects the eardrum
Protects the eardrum
„
„ Wax
Wax

02/07/08
6
Structures of the Middle Ear
Structures of the Middle Ear
„ Tympanic Membrane
„ Tympanic Cavity
„ Ossicles
„ Middle Ear Muscles
„ Eustachian Tube
„ Mastoid

02/07/08
7
Tympanic Membrane
Tympanic Membrane
„
„ The eardrum separates the outer ear
The eardrum separates the outer ear
from the middle ear
from the middle ear
„
„ Creates a barrier that protects the
Creates a barrier that protects the
middle and inner areas from foreign
middle and inner areas from foreign
objects
objects
„
„ The eardrum vibrates in response to
The eardrum vibrates in response to
sound pressure waves.
sound pressure waves.
„
„ Changes acoustic energy into
Changes acoustic energy into
mechanical energy
mechanical energy

02/07/08
8
Ossicles
Ossicles
„
„ Malleus (hammer)
Malleus (hammer)
„
„ Incus (anvil)
Incus (anvil)
„
„ Stapes (stirrup) smallest bone of the
Stapes (stirrup) smallest bone of the
body
body

02/07/08
9
Middle Ear Muscles
Middle Ear Muscles
„
„ Tensor tympani
Tensor tympani
•
• Attached to malleus
Attached to malleus
„
„ Stapedius
Stapedius
•
• Attached to stape
Attached to stape
„
„ Middle Ear Muscle Function:
Middle Ear Muscle Function:
•
• Help maintain ossicles in proper position
Help maintain ossicles in proper position
•
• Protect inner ear from excessive sound levels
Protect inner ear from excessive sound levels
•
• This protective reflex termed "acoustic reflex"
This protective reflex termed "acoustic reflex"

02/07/08
10
Eustachian Tube
Eustachian Tube
„
„ The ET connects the front wall of the
The ET connects the front wall of the
middle ear with the nasopharynx
middle ear with the nasopharynx
„
„ It operates like a valve, which opens
It operates like a valve, which opens
during swallowing and yawning
during swallowing and yawning
„
„ It equalizes the pressure on either
It equalizes the pressure on either
side of the eardrum, which is
side of the eardrum, which is
necessary for optimal hearing.
necessary for optimal hearing.

02/07/08
11
Mastoid
Mastoid
„
„ Bony ridge behind the auricle
Bony ridge behind the auricle
„
„ Connect with middle ear
Connect with middle ear
„
„ Can get infected ( Mastoiditis)
Can get infected ( Mastoiditis)

02/07/08
12
Function of Middle Ear
Function of Middle Ear
„
„ Conduction
Conduction
„
„ Protection
Protection
„
„ Transducer
Transducer
„
„ Amplifier
Amplifier

02/07/08
13
Amplifier
Amplifier
„
„ The middle ear enhances the transfer
The middle ear enhances the transfer
of acoustical energy in two ways:
of acoustical energy in two ways:
•
• The area of the eardrum is about 17
The area of the eardrum is about 17
times larger than the oval window
times larger than the oval window
„
„ The effective pressure (force per unit area)
The effective pressure (force per unit area)
is increased by this amount.
is increased by this amount.
•
• The ossicles produce a lever action that
The ossicles produce a lever action that
further amplifies the pressure
further amplifies the pressure

02/07/08
14
Structures of the Inner Ear
Structures of the Inner Ear
„
„ Cochlea
Cochlea
„
„ Vestibule
Vestibule
„
„ Semicircular canals
Semicircular canals

02/07/08
15
Cochlea
Cochlea
„
„ Snail
Snail-
-shaped organ
shaped organ
with a series of
with a series of
fluid
fluid-
-filled tunnels
filled tunnels
„
„ converts
converts
mechanical energy
mechanical energy
into electrical
into electrical
energy
energy
„
„ It contain
It contain Organ of
Organ of
Corti
Corti ( end organ of
( end organ of
hearing)
hearing)

02/07/08
16
Traveling Waves
Traveling Waves

02/07/08
17
Vestibular System
Vestibular System
„
„ Consists of vestibule and three semi
Consists of vestibule and three semi-
-
circular canals
circular canals
„
„ Shares fluid with the cochlea
Shares fluid with the cochlea
„
„ Controls balance
Controls balance
„
„ No part in hearing process
No part in hearing process

02/07/08
18
Central Auditory Pathway
Central Auditory Pathway
„
„ Pathway between
Pathway between
cochlea and
cochlea and
auditory cortex
auditory cortex
„
„ Cochlear nerve
Cochlear nerve
„
„ Cochlear nucleus
Cochlear nucleus

02/07/08
19
Causes of Tinnitus
Causes of Tinnitus
„
„ Local causes
Local causes
Every ear disease can be associated
Every ear disease can be associated
with deafness
with deafness
„
„ General Causes
General Causes
Cardiovascular disease
Cardiovascular disease
Neurological conditions
Neurological conditions

02/07/08
20
Classification of Tinnitus
Classification of Tinnitus
„
„ Unilateral or bilateral
Unilateral or bilateral
„
„ Subjective or objective
Subjective or objective
„
„ Pulsatile or non pulsatile
Pulsatile or non pulsatile

02/07/08
21
Key Points in History
Key Points in History
„
„ Accompanying ear disease
Accompanying ear disease
„
„ History of noise exposure
History of noise exposure
„
„ Trauma
Trauma
„
„ Ototoxic medications
Ototoxic medications
„
„ Systemic Diseases
Systemic Diseases

02/07/08
22
THANK YOU
THANK YOU

atsganatomyphysiologyofhteear.pdf

Recommended

Recommended

More Related Content

Similar to atsganatomyphysiologyofhteear.pdf

Similar to atsganatomyphysiologyofhteear.pdf (20)

More from EidTahir

More from EidTahir (20)

Recently uploaded

Recently uploaded (20)

atsganatomyphysiologyofhteear.pdf