Exam 3: Ear

Question 1

Hearing (Audition)

Answer 1

-detecting sound waves and converting them into nerve impulses

Question 2

Equilibrium (Balance)

Answer 2

-detect position of head

Question 3

External Ear

Answer 3

-consists of auricle, external acoustic meatus and tympanic membrane

Question 4

Auricle (Pinna)

Answer 4

• outer mass of tissue

- function: collects sound waves to external acoustic meatus

Question 5

External Acoustic Meatus

Answer 5

• between auricle and tympanic membrane

- function: directs sound to tympanic membrane

Question 6

Tympanic Membrane (Eardrum)

Answer 6

-function: move/vibrate auditory ossicles when sound waves vibrate membrane

Question 7

Middle Ear

Answer 7

-lateral (external) boundary is tympanic membrane
-medial (internal) boundary is oval window and round window
-contains auditory ossicles (ear bones)
and auditory tube

Question 8

Auditory Ossicles

Answer 8

• malleus (hammer), incus (anvil), stapes (stirrup)
• connects with oval window of inner ear (where sound waves are transmitted to inner ear)
• Function: transmit and amplify sound waves to inner ear

Question 9

Auditory Tube

Answer 9

• connects middle ear with nasopharynx (upper throat

- function: equalizes pressure in middle ear

Question 10

Popping sensation when changing altitudes

Answer 10

-Caused by auditory tube opening and releasing pressure

Question 11

Inner Ear

Answer 11

-consists of bony labyrinth and membranous labyrinth

Question 12

Bony Labyrinth

Answer 12

• spaces/cavities inside temporal bone

- consists of vestibule, semicircular canals, and cochlea

Question 13

Membranous Labyrinth

Answer 13

• membranous sacs/tubes that rest inside the bony labyrinth

- consists of utricle, saccule, semicirular ducts, and cochlear duct (scala media)

Question 14

Perilymph

Answer 14

• fluid between bony and membranous labyrinth

- similar to CSF (in composition and function)

Question 15

Endolymph

Answer 15

• fluid inside membranous labyrinth
• different chemically from perilymph
• helps conduct sound waves

Question 16

Vestibule

Answer 16

-oval central portion of bony labyrinth

Question 17

Semicircular Canals

Answer 17

-three circular spaces/canals in bony labyrinth

Question 18

Cochlea

Answer 18

-spiral chamber of bony labyrinth

Question 19

Utricle

Answer 19

• sac inside vestibule
• membranous labyrinth
• involved in interpreting equilibrium

Question 20

Saccule

Answer 20

• another sac inside vestibule
• membranous labyrinth
• involved in interpreting equilibrium

Question 21

Semicircular Ducts

Answer 21

• three membranous tubes in semicircular canals
• membranous labyrinth
• involved in interpreting equilibrium

Question 22

Cochlear Duct (Scala Media)

Answer 22

• membranous tube inside cochlea
• membranous labyrinth
• involved in hearing
• splits cochlea into two chambers

Question 23

How is equilibrium information transmitted?

Answer 23

-through vestibular branch of vestibulocochlear nerve CN VIII

Question 24

Scala Vestibuli

Answer 24

• above cochlear duct
• filled with perilymph
• part of cochlea (bony labyrinth)
• connects to oval window

Question 25

Oval Window

Answer 25

-directs sound waves through scala vestibuli

Question 26

Scala Tympani

Answer 26

- below cochlear duct - filled with perilymph - part of cochlea (bony labyrinth) - connects to round window

Question 27

Round Window

Answer 27

-excess sound waves leave inner ear through this

Question 28

Spiral Organ (Organ of Corti)

Answer 28

- filled with endolymph - contained in cochlear duct - rests on basilar membrane - contains hair cells with have stereocilla (touch tectorial membrane)

Question 29

How sound waves travel

Answer 29

- when sound waves enter via the scala vestibuli, they vibrate a small portion of the basilar memrane - when the basilar membrane moves the stereocilia of the hair cells touch the tectorial membrane - bending of the stereocilia generates a nerve impulse - nerve impulses are sent to the brain via the cochlear brance of the vestibulocochlear nerve CN VIII - remaining sound waves are transferred to the scala tympani and exit the inner ear via the round window

Question 30

Complete (Brief) Overview of Hearing

Answer 30

- Sound waves are collected by auricle, travel in external acoustic meatus, sent to tympanic membrane - Vibration of tympanic membrane causes vibration of auditory ossicles, wich in turn vibrates the oval window - Sound waves travel through the scala vestibuli and vibrates a portion of the basilar membrane (which is attached to spiral organ) - Stereocilia of the hair cells bend against the tectorial membrane which generates a nerve impulse - Nerve impulse is sent to the brain via the vestibulocochlear nerve CN VIII - remaining sound waves are transferred to the scala tympani and leave the inner ear through the round window

Question 31

Otitis Media

Answer 31

- inflammation of middle ear - may occur after respiratory infection - spreads to auditory tube - pain and pressure in middle ear - can rupture tympanic membrane

Question 32

Myringotomy

Answer 32

- surgical procedure to to put in tubes in tympanic membrane - for chronic ear infections - help drain fluid in middle ear

Question 33

Frequencies and Basilar Membrane

Answer 33

- low notes (frequencies) vibrate basilar membrane far away from oval window - high notes (frequencies) vibrate basilar membrane close to oval window