anatomi dan fisiologi telinga 2012

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Divided into 4 parts (by function): Outer Ear Middle Ear Inner Ear Central Auditory Nervous System

The

Pinna cartilaginous, highly variable in appearance, some landmarks.

External

Auditory Canal (or external auditory meatus) 2.5 cm tube.

Auricle (Pinna) Gathers sound waves Aids in localization Amplifies sound approx. 5-6 dB

lateral

portion-cartilage medial portion-osseous lined with epidermal (skin) tissue hairs in lateral part cerumen (ear wax) secreted in lateral part.

Approx. 1 inch long S shaped Outer 1/3 surrounded by cartilage; inner 2/3 by mastoid bone Allows air to warm before reaching TM Isolates TM from physical damage Cerumen glands moisten/soften skin Presence of some cerumen is normal

Lining

is mucous membrane Tympanic Membrane separates it from EAC Eustachian tube connects it to nasopharynx Also Connected to Mastoid Air Cells

Thin membrane Forms boundary between outer and middle ear Vibrates in response to sound waves Changes acoustical energy into mechanical energy

(From Merck Manual)

Ossicular chain = malleus, incus & stapes Malleus

TM attaches at Umbo Connector function

Incus

StapesSmallest bone in the body Footplate inserts in oval window on medial wall

Focus/amplify vibration of TM to smaller area, enables vibration of cochlear fluids

Mucous-lined, connects middle ear cavity to nasopharynx Equalizes air pressure in middle ear Normally closed, opens under certain conditions May allow a pathway for infection Children grow out of most middle ear problems as this tube lengthens and becomes more vertical

1. The Stapedius Attaches to Stapes,Contracts in

Response to Loud sounds, chewing, speaking; Facial (VIIth cranial) nerve 2. The Tensor Tympani Helps open Eustachian tube

Impedance Filtering Acoustic

Matching

Reflex

Two Halves: Vestibular--transduces motion and pull of gravity Cochlear--transduces sound energy (Both use Hair Cells)

The end organ of hearing

Contains stereocilia & receptor hair cells 3 rows OHC, 1 row IHC Tectorial and Basilar Membranes Cochlear fluids

(From Augustana College, Virtual Tour of the Ear)

Frequency specificHigh pitches= base of cochlea Low pitches= apex of cochlea Fluid movement causes deflection of nerve endings Nerve impulses (electrical energy) are generated and sent to the brain

Transduction-

Converting acousticalmechanical energy into electro-chemical energy. Analysis-Breaking sound up into its component frequencies

Frequency

Bekesys Traveling Wave Active Tuning from OHCs

VIIIth

cranial nerve Cochlear Nucleus Superior Olivary Complex Lateral Lemniscus Inferior Colliculus Medial Geniculate Body Primary Auditory Cortex

Brainstem Mid-brain

Thalamus Temporal Lobe

Corpus Callosum

4th Ventricle

Pons

Cerebellum

Thalamus

VIIIth Cranial Nerve or Auditory Nerve Bundle of nerve fibers (25-30K) Travels from cochlea through internal auditory meatus to skull cavity and brain stem Carry signals from cochlea to primary auditory cortex, with continuous processing along the way

Auditory Cortex Wernickes Area within Temporal Lobe of the brain Sounds interpreted based on experience/association

Pattern

RecognitionDiscrimination of Sounds

Duration

Localization Selective

Attention

Language

Processing in the left hemisphere. (Remember the right ear has the strongest connections to the left hemisphere) Most

people show a right-ear advantage in processing linguistic stimuli

Thank you