The EarThe EarMarlene ArceoMarlene Arceo

Leonardo CabreraLeonardo Cabrera

Isaac BrabbIsaac Brabb

Melanie WeyersMelanie Weyers

General functions of the earGeneral functions of the ear

1.1. Two Main FunctionsTwo Main Functions::i.i. Assist with balance of individualAssist with balance of individual

ii.ii. Collect sounds and relay them to the brainCollect sounds and relay them to the brain

Outer earOuter ear1.1. StructureStructure::

i.i. Made of tough cartilage covered by skinMade of tough cartilage covered by skin

ii.ii. Contains external acoustic meatusContains external acoustic meatus

a)a) Secrets cerumen (protects ear canal)Secrets cerumen (protects ear canal)

b)b) Guarded by hairGuarded by hair

c)c) Ends at the tympanic membrane Ends at the tympanic membrane (eardrum)(eardrum)

Outer ear (Cont.)Outer ear (Cont.)

1.1. Function:Function:i.i. AuricleAuricle

a)a) Collects sound waves travelling through airCollects sound waves travelling through air

b)b) Directs sound waves into external acoustic Directs sound waves into external acoustic meatusmeatus

c)c) Sound waves travel through tube all the way to Sound waves travel through tube all the way to the tympanic membranethe tympanic membrane

ii.ii. Tympanic MembraneTympanic Membranea)a) Semitransparent membrane covered by thin layer Semitransparent membrane covered by thin layer

of skin on outside / mucous on insideof skin on outside / mucous on inside

b)b) Oval margin / cone shapedOval margin / cone shaped

c)c) Moves back and forth in response to sound wavesMoves back and forth in response to sound waves

d)d) Whatever sound wave enters the canal becomes Whatever sound wave enters the canal becomes processed and moves on to middle earprocessed and moves on to middle ear

Middle earMiddle ear

-An air-filled, -An air-filled, membrane lined membrane lined space internal to space internal to the the eardrum/tympanic eardrum/tympanic membrane and membrane and external to the external to the oval window of the oval window of the cochleacochlea

-couples sound -couples sound from air to the from air to the fluid via the oval fluid via the oval windowwindow

Middle ear-Eustachian Middle ear-Eustachian TubeTube

• Links the nasopharynx to the middle Links the nasopharynx to the middle earear

• Remains closed under normal Remains closed under normal conditionsconditions

1. Pressure Equalization1. Pressure Equalizationa)a) When pressure inside middle ear is When pressure inside middle ear is

different form pressure of atmosphere, different form pressure of atmosphere, the tube can be opened from yawning, the tube can be opened from yawning, swallowing, or chewing because it lets swallowing, or chewing because it lets small amounts of air and equalizes the small amounts of air and equalizes the pressurespressures

2. Mucus Drainage2. Mucus Drainagea)a) Eustachian tube allows fluid/mucus to Eustachian tube allows fluid/mucus to

drain out of the ear.drain out of the ear.

Middle Ear-OSSICLESMiddle Ear-OSSICLES

1.1. 3 small, movable bones 3 small, movable bones

• Vibrate when the Vibrate when the eardrum/tympanic membrane eardrum/tympanic membrane vibrates from sound waves vibrates from sound waves entering the ear canalentering the ear canala)a) Hammer (malleus)Hammer (malleus)

i.i. Bone connected to inside of the Bone connected to inside of the tympanic membrane and to the tympanic membrane and to the incus/anvilincus/anvil

ii.ii. Transmits sound vibrations to Transmits sound vibrations to the incusthe incus

b)b) Anvil (incus)Anvil (incus)i.i. Second bone connected to Second bone connected to

hammer to the stapeshammer to the stapesc)c) Stirrup (stapes)Stirrup (stapes)

i.i. The third U-shaped bone The third U-shaped bone connected to the stirrup and to connected to the stirrup and to cochleacochlea

ii.ii. Smallest bone in the bodySmallest bone in the body

MuslcesMuslces

• Tympanic/Acoustic Reflex: muslces contract in Tympanic/Acoustic Reflex: muslces contract in response to loud sounds, thereby reducing response to loud sounds, thereby reducing the transmission of sound to the inner earthe transmission of sound to the inner ear

• Stapedius muscle-(smallest skeletal muscle in Stapedius muscle-(smallest skeletal muscle in the body) connects to the stapes and is the body) connects to the stapes and is controlled by the facial nervecontrolled by the facial nerve

• Stapetensor tympanic muscle-connects to the Stapetensor tympanic muscle-connects to the base of the malleus and is under the control base of the malleus and is under the control of the medial pterygoid nerveof the medial pterygoid nerve

NervesNerves

• horizontal and horizontal and chorda tympanichorda tympani branches of branches of the facial nerve pass through the middle ear the facial nerve pass through the middle ear spacespace

• Damage to the horizontal branch during Damage to the horizontal branch during surgery can lead to partial mastoid process surgery can lead to partial mastoid process paralysis paralysis

Inner Ear (video)Inner Ear (video)

Inner EarInner Ear

1.1. Location:Location:a)a) Within temporal Within temporal

bonebone

2.2. Functions:Functions:a)a) Hearing and balanceHearing and balance

3.3. Structures:Structures:a)a) ““Bony Labyrinth”Bony Labyrinth”

b)b) ““Membranous Membranous Labyrinth”Labyrinth”

c)c) Round WindowRound Window

d)d) Eighth Cranial NerveEighth Cranial Nerve

e)e) Contains perilymph Contains perilymph and Endolymph Fluidand Endolymph Fluid

Bony vs. Membranous Bony vs. Membranous LabyrinthLabyrinth

1.1. Bony LabyrinthBony Labyrintha)a) Ducts created by the Ducts created by the

grooves and channels in the grooves and channels in the temporal bonetemporal bone

b)b) LargerLarger

c)c) Contains PerilymphContains Perilymph

d)d) Ex: Outer Tire of a BikeEx: Outer Tire of a Bike

2.2. Membranous LabyrinthMembranous Labyrintha)a) Located INSIDE of the Bony Located INSIDE of the Bony

LabyrinthLabyrinth

b)b) SmallerSmaller

c)c) Contains EndolymphContains Endolymph

d)d) Ex: Inner tube of Bike TireEx: Inner tube of Bike Tire

Perilymph vs. Endolymph Perilymph vs. Endolymph FluidFluid

1.1. Perilymph FluidPerilymph Fluida)a) Similar Similar

composition to CSFcomposition to CSF

b)b) Rich in SodiumRich in Sodium

c)c) Located in Bony Located in Bony LabyrinthLabyrinth

d)d) Shock bufferShock buffer

e)e) Helps transmit Helps transmit waves to waves to membranous membranous labyrinthlabyrinth

2.2. Endolymph FluidEndolymph Fluida)a) Where actual perception of Where actual perception of

balance, equilibrium, and balance, equilibrium, and sound take placesound take place

b)b) Rich in PotassiumRich in Potassium

c)c) Located in Membranous Located in Membranous LabyrinthLabyrinth

CochleaCochlea

1. Snail like structure for hearing1. Snail like structure for hearing

2. Converts sounds and vibrations from the external 2. Converts sounds and vibrations from the external environment into electrical impulsesenvironment into electrical impulses

3. 3. TransductionTransductioni.i. When vibrations are made into impulses able to be When vibrations are made into impulses able to be

interpreted by the braininterpreted by the brain

ii.ii. Vibrations stimulate oval window, causes the fluid to Vibrations stimulate oval window, causes the fluid to move through cochlea to the Organ of Cortimove through cochlea to the Organ of Corti

a)a) Sensory nerve “hair-like” receptors in the cochleaSensory nerve “hair-like” receptors in the cochlea

4. Sensory cells in the cochlea perform transduction 4. Sensory cells in the cochlea perform transduction and the electrical impulse travels to the brain via and the electrical impulse travels to the brain via Cochlear nerveCochlear nerve

CochleaCochlea

Semicircular CanalsSemicircular Canals

1.1. Mainly for balance and steadinessMainly for balance and steadiness

2.2. Contains Perilymph and Endolymph Contains Perilymph and Endolymph

3.3. When the body (especially the head) When the body (especially the head) changes position, endolymph moves, hair changes position, endolymph moves, hair cells in the canal sense the movement and cells in the canal sense the movement and relay the information to the brain.relay the information to the brain.a)a) Helps sense movement of the body and maintain Helps sense movement of the body and maintain

balancebalance

Semicircular CanalsSemicircular Canals

VestibuleVestibule

1.1. Regulates balance and equilibriumRegulates balance and equilibriuma)a) Connects the semicircular valves and the cochleaConnects the semicircular valves and the cochlea

2.2. Also contains hair cells that sense changes in the Also contains hair cells that sense changes in the waves and flow of Endolymph fluid to help maintain waves and flow of Endolymph fluid to help maintain balancebalance

3.3. Vestibular nerve relays information to regulate Vestibular nerve relays information to regulate balance and equilibriumbalance and equilibriuma)a) Does not require conscience changes from the cerebrumDoes not require conscience changes from the cerebrumb)b) The body will automatically adjust itselfThe body will automatically adjust itself

4.4. These help detect Lateral/Horizontal movementThese help detect Lateral/Horizontal movementa)a) Saccule: Inferior Portion of VestibuleSaccule: Inferior Portion of Vestibuleb)b) Utricle: Superior Portion of VestibuleUtricle: Superior Portion of Vestibule

VestibuleVestibule

Round WindowRound Window

1.1. Location:Location:a)a) Inner ear between the Inner ear between the

middle ear and the middle ear and the cochleacochlea

2.2. Senses vibrations from Senses vibrations from middle ear, then middle ear, then indents into the inner indents into the inner ear to stimulate waves ear to stimulate waves and movement of and movement of perilymph fluid.perilymph fluid.

3.3. Release to decrease Release to decrease pressure within the earpressure within the ear

Static equilibriumStatic equilibrium1.1. Organs involved are located within utricle and sacculeOrgans involved are located within utricle and saccule

2.2. Utricle and saccule contain hair cells that project vertically or Utricle and saccule contain hair cells that project vertically or horizontally depending between utricle and sacculehorizontally depending between utricle and saccule

3.3. Hair contacts sheet of gelatinous material that ahs calcium carbonate Hair contacts sheet of gelatinous material that ahs calcium carbonate crystals embeddedcrystals embedded

4.4. The hair cells have nerve fibers wrapped around their basesThe hair cells have nerve fibers wrapped around their bases

5.5. Gravity stimulates hair cells to respond (i.e. bending head)Gravity stimulates hair cells to respond (i.e. bending head)

6.6. Gelatinous material sags in response to gravityGelatinous material sags in response to gravity

7.7. Stimulates hair cells, signal associated nerve fibersStimulates hair cells, signal associated nerve fibers

8.8. Nerve impulses travel to the CNSNerve impulses travel to the CNS

9.9. Informs brain of head’s positionInforms brain of head’s position

10.10. Brain responds bye sending motor impulses to skeletal muscles which Brain responds bye sending motor impulses to skeletal muscles which maintain balance maintain balance

Static equilibriumStatic equilibrium

Dynamic equilibriumDynamic equilibrium

1.1. 3 semicircular canals that are responsible for 3 semicircular canals that are responsible for detecting changes in motion.detecting changes in motion.

2.2. In each canal there is an ampullaIn each canal there is an ampulla

3.3. Communicates with utricleCommunicates with utricle

4.4. Contains sensory organ crista ampullarisContains sensory organ crista ampullaris

5.5. Also contains sensory hair cellsAlso contains sensory hair cells

6.6. When the head or torso moves, the semicircular When the head or torso moves, the semicircular canals move as wellcanals move as well

7.7. This causes the hairs to bend, stimulating associated This causes the hairs to bend, stimulating associated nerve fibers and as a result impulses travel to the nerve fibers and as a result impulses travel to the brain.brain.

Dynamic equilibriumDynamic equilibrium

Ménière’s DiseaseMénière’s Disease• Disease of the inner ear that causes vertigo (severe Disease of the inner ear that causes vertigo (severe

dizziness), ringing in the ears, hearing loss, and feeling dizziness), ringing in the ears, hearing loss, and feeling of congestion in the ear. of congestion in the ear.

• Usually affects only one earUsually affects only one ear

• Symptoms can be caused bySymptoms can be caused by::1.1. The buildup of fluid in compartments of the ear (labyrinth)The buildup of fluid in compartments of the ear (labyrinth)2.2. It interferes with the normal balance and hearing signals It interferes with the normal balance and hearing signals

between the inner ear and the brainbetween the inner ear and the brain

• How is it diagnosedHow is it diagnosed::1.1. Medication to treat dizzinessMedication to treat dizziness2.2. Limit salt in diet / taking diureticsLimit salt in diet / taking diuretics3.3. Inject antibiotics (gentamicin) into the middle earInject antibiotics (gentamicin) into the middle ear

Ménière’s DiseaseMénière’s Disease

OtitisOtitis• General term for infection or inflammation of the ear.General term for infection or inflammation of the ear.

• Classified according to whether it occurs suddenly for a short time or repeatedly over a long Classified according to whether it occurs suddenly for a short time or repeatedly over a long period of timeperiod of time

• Otitis ExternaOtitis Externa

1.1. When it involved the outer ear and ear canalWhen it involved the outer ear and ear canal

2.2. Also called swimmers earAlso called swimmers ear

• Otitis MediaOtitis Media

1.1. Involves the middle earInvolves the middle ear

2.2. Also called ear infectionAlso called ear infection

• Acute Ear InfectionAcute Ear Infection

1.1. Often painfulOften painful

2.2. Starts suddenly / short period of timeStarts suddenly / short period of time

• Chronic Ear InfectionChronic Ear Infection

1.1. Ear infection does not go away / keeps reoccurringEar infection does not go away / keeps reoccurring

2.2. Can cause long term ear damageCan cause long term ear damage

OTITIS MEDIA VS OTITIS MEDIA VS NORMAL MIDDLE EARNORMAL MIDDLE EAR

Works CitedWorks CitedCenters for Disease Control and PreventionCenters for Disease Control and Prevention. Centers for Disease Control . Centers for Disease Control and Prevention, 30 Sept. 2013. Web. 31 Mar. 2014.and Prevention, 30 Sept. 2013. Web. 31 Mar. 2014.

"Ears and Hearing." "Ears and Hearing." InnerBodyInnerBody. N.p., n.d. Web. 31 Mar. 2014.. N.p., n.d. Web. 31 Mar. 2014.

The Editors of Encyclopædia Britannica. "Vestibule (ear)." The Editors of Encyclopædia Britannica. "Vestibule (ear)." Encyclopedia Encyclopedia Britannica OnlineBritannica Online. Encyclopedia Britannica, n.d. Web. 31 Mar. 2014.. Encyclopedia Britannica, n.d. Web. 31 Mar. 2014.

"Ménière's Disease." "Ménière's Disease." [NIDCD Health Information][NIDCD Health Information]. N.p., n.d. Web. 29 Mar. . N.p., n.d. Web. 29 Mar. 2014.2014.

"Neuroscience for Kids - The Ear." "Neuroscience for Kids - The Ear." Neuroscience for Kids - The EarNeuroscience for Kids - The Ear. N.p., . N.p., n.d. Web. 31 Mar. 2014.n.d. Web. 31 Mar. 2014.

"Special Senses II: The Ear." "Special Senses II: The Ear." Special Senses II: The EarSpecial Senses II: The Ear. N.p., n.d. Web. . N.p., n.d. Web. 31 Mar. 2014.31 Mar. 2014.

"X. The Organs of the Senses and the Common Integument. 1d. 4. The "X. The Organs of the Senses and the Common Integument. 1d. 4. The Internal Ear or Labyrinth. Gray, Henry. 1918. Anatomy of the Human Internal Ear or Labyrinth. Gray, Henry. 1918. Anatomy of the Human Body." Body." X. The Organs of the Senses and the Common Integument. 1d. 4. X. The Organs of the Senses and the Common Integument. 1d. 4. The Internal Ear or Labyrinth. Gray, Henry. 1918. Anatomy of the Human The Internal Ear or Labyrinth. Gray, Henry. 1918. Anatomy of the Human Body.Body. N.p., n.d. Web. 31 Mar. 2014. N.p., n.d. Web. 31 Mar. 2014.