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Departemen Anatomi

�Contain receptors for hearing & awareness of head position & movement

�Divided into :I. External ear � receives & directs

sound waves from external environment

II. Middle ear � tranforms sound waves into mechanical vibrations

III.Inner ear :o Mechanical vibration converted to nerve impulses & relayed to brain to be interpreted as sound

o Contain vestibular organs that function in balance

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� Auricle / pinna consist of :◦ Irregular plate of elastic cartilage, surrounded by thick pericondrium

◦ Skin with a few small hairs◦ Sebaceous gland & sweat gland◦ Sheets of skeletal muscle

� External auditory meatus :◦ An open S-shaped course◦ Lined by keratinized stratified squamous epith.

◦ Ceruminous gland :� Secretory cells : cuboidal to collumnar� Produced cerumen ( a waxy material that prevents drying of skin lines meatus)

� Auditory ossicles :◦ Malleus � M. tensor tymphani

◦ Incus◦ Stapes � M. stapedius

� Tympanic cavity � Lined by mucous membrane with a simple squamous epith.

� Tympanic membrane :◦ 3 layers :� Outer : stratified squamous epith

� Middle : 2 layers of collagenous fibers

� Inner : a simple squamous epith

◦ Inner surface attaches to malleus

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� Auditory tube / eustachian tube :◦ 4 cm long

◦ Connect anterior part of tympanic cavity with nasopharynx

◦ Wall of auditory tube :

� 1/3 near tympanic cavity supported by compact bone with simple columnar epith

� 2/3 medial supported by J-shaped elastic cartilage with ciliated pseudostratified columnar epith.

� Consist of :1. Periboney labyrinth / osseosa

labyrinth� filled with perilymph2. Membranous labyrinth � filled with

endolymph� Periboney & membranous labyrinth major components :a. Vestibular labyrinth � contain sensory

element for equlibrium b. Cochlea � contain sensory stuctures

for hearing� Perilymph :

◦ Resembles extracellular fluid (↑ sodium ions, ↓potassium ions)

◦ Production site : unknown� Endolymph :

◦ Resembles intracellular fluid ( ↑ potassium ion, ↓ sodium ions )

◦ Produced by striae vascularis (an area of cochlear duct)

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� Consist of 3 semisicular canals � utricle � saccule

� Most membranous labyrinth lined by simple squamous epith

� Sensory epithelium :◦ Stratified epith, found in spesific region of membranous labyrinth

◦ In semisircular canal �cristae ampularis

◦ Utricle � macula utriculi◦ Saccule �macula sacculi

◦ 3 type cells : hair cells type I & II, supporting (sustentacular) cells

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� Type I hair cells :◦ Flask-shaped with narrow apical region

◦ Rounded base contain nucleus

◦ Apical membrane bears 50-100 large, non motile microvilli, known as “hair”.

◦ Kinocilium : a single, eccentrically placed cilium, present on apical surface

� Type II hair cells �Similar to type I, but the cells are collumnar

� Supporting / sustentacular cells :◦ Columnar shaped◦ Function unknown◦ At periphery � planum semilunatum (simple columnar layer, lacks hair cells)

� Microvilli of hair cells in cristae embeded in gelatinous structure called cupula cristae ampullaris

� Microvilli of hair cells in maculae embeded in viscous proteoglycan, forms otholitic membrane. Numerous crystalline bodies / otolith suspended in this layer

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� Consist of : ◦ Outer portion of compact bone

◦ A central membranous part

� Osseous cochlea :◦ Mediolus

◦ Spiral lamina � basilar

membrane & vestibular membrane

◦ Spiral ligament

� Cochleal canal divided by basilar & vestibular membrane into :1. Upper scala vestibuli �

perilymph2. Scala media �

endolymph3. Lower scala tympani �

perilymph

� Striae vascularis :◦ Pseudostratified

columnar epith ◦ Contain basal &

marginal cells◦ Marginal cell may

elaborte in endolymph

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� Organ of corti :◦ Specialized cells on

scala media that transform vibrations of basilar membrane to nerve impulse

◦ Supporting cells �a tall columnar, consist of :1. Inner & outer

pillar cells2. Inner & outer

phalangeal cells

3. Border cells4. Cells of hensen

5. Cells of claudius

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1. Histologi Dasar, 8th

Edition, L. Carlos Junquira MD, Jose

Carneiro MD, Robert O. Kelley PhD, EGC, 1995.

2. Essentials of Human Histology, 2nd Edition, William J. Krausse PhD, Little Brown & Company

(Inc), 1996. Pp

3. Atlas Histologi Manusia, 6th Edition, Mariano S. H. di Fiore, EGC, 1992.