Lecture 5 (Revised) (Ear)

Question 1

Outer Ear?

Answer 1

Receives incoming sound waves
(auricle (pinna) –> external auditory meatus –> tympanic membrane (eardrum))
(lined with stratified squamous epithelium + elastic cartilage)
(ceruminous glands produce ear wax)

Question 2

Middle Ear?

Answer 2

Transmits sound from outer to inner ear
(housed in tympanic cavity)
(lined with simple squamous epithelium)
(auditory (eustachian) tube (ciliated pseudostratified))
(ossicles)
(round window impulses)

Question 3

Inner Ear?

Answer 3

Hearing + Balance
(bony labyrinth)
(membranous labyrinth)

Question 4

Bony Labyrinth?

Answer 4

Carved out temporal bone and contains perilymph (fluid)
Surrounds:
-Cochlea
-Vestibule
-3 semicircular canals

Question 5

Membranous Labyrinth?

Answer 5

Lines inside of bony labyrinth and contains endolymph (fluid)
-Surrounds:
-Cochlear duct
-Saccule + Utricle
-Semicircular ducts

Question 6

Cochlea is responsible?

Answer 6

For hearing
(covered by bony labyrinth)
(contains cochlear duct –> covered by membranous labyrinth)

Question 7

3 Chambers of Cochlea?

Answer 7

-Scala Vestiboli
-Scala Media
-Scala Tympani

Question 8

Cochlea Duct?

Answer 8

Scala Media (with endolymph)
Contains:
-Organ of corti
-Hair cells with stereocilia
-Tectorial membrane
-Basilar membrane

Question 9

Displacement of stereocilia in hair cells of tectorial membrane results in?

Answer 9

Generation of APs (ex. neural impulse)

Question 10

Steps involved in transmission of sound waves?

Answer 10

1) Sound travels up scala vestibule makes waves in perilymph and transferred to scala media (endolymph)
2) Waves in endolymph move basilar membrane stimulates hair cells and stereocilia move against tectorial membrane
3) Sound is turned into APs and neural impulses

Question 11

Excess vibrations travel down?

Answer 11

Scala Tympani (absorbed by round window)

Question 12

Inner Ear - Crista Ampullaris?

Answer 12

-Located in semicircular duct (membranous labyrinth)
-Angular motion (acceleration)
-Covered by cupola (gelatinous membrane)

Question 13

Inner Ear - Maculae?

Answer 13

-Located in saccule + utricle of vestibule
-Gravity and linear acceleration
-Covered by otoconia (little crystals push down on stereocilia of hair cells)
-Kinocilium (microtubules interact with stereocilia displaced by otoconia)