Microantomy of the Ear

Question 1

Name chambers of Ear

Answer 1

1- Outer ear
2- Middle ear
3- inner ear

Question 2

Where is the amplifying of sound done

Answer 2

Middle ear

Question 3

Where is the sensory perception of sound done

Answer 3

Inner ear

Question 4

What is the role of the ear

Answer 4

Controls sense of hearing and balance ( vestibular apparatus )

Question 5

Where are receptors located in the ear ( where hearing and balance is perceived )

Answer 5

Petrous part of the temporal bone

Question 6

What makes up the outer ear ( give details )

Answer 6

1- Elastic cartilage covered by epithelium = pinae
2- external auditory meatus = external canal extending from cartilage surface into temporal bone
2- tympanic membrane ( ear drum ) : collagenous bilayer where vibration is transmitted to the middle ear

Question 7

The external auditory canal is lined by ?

Answer 7

stratified squamous epithelium filled with hair follicles and sebaceous glands

Question 8

What is the ceruminous glands

Answer 8

Modified sweat glands , secreting wax that has a protective function. Protects tympanic membrane

Question 9

Between the two epithelial layers of the tympanic membrane is what

Answer 9

Tough connective tissue

Question 10

What makes up the middle ear ( gives details )

Answer 10

1- Tympanic cavity : air filled space in the temporal bone
2- Eustachian tube connecting tympanic cavity with nasopharynx : opens during swelling to equilibrate air pressure on either side of ear drum
3- Auditory Ossicles : 3 bones transmit vibrations form tympanic membrane to oval window ( Malleus , Incus , stapes bone )

Question 11

What are the two openings of the Middle ear

Answer 11

Oval and round window that lead into the inner ear

Question 12

What are the ossicles suspended by in the middle ear

Answer 12

By ligaments

Question 13

What are the ossicles composed of

Answer 13

Compact bone and articulated by sundial joints

Question 14

Which ossicle is connected to the oval window

Answer 14

Stapes bone

Question 15

What is the function of the Ossicles

Answer 15

Convert sound waves to mechanical vibrations in tissues and fluid-filled chambers. Amplify sounds which allows mechanical energy to be transmitted into ta fluid medium.

Question 16

Which muscles dampen effects of loud noise and reduce movement of ossicles

Answer 16

Stapedius and tensor tympani

Question 17

What are the components of the inner ear

Answer 17

1- Bony outer labyrinth : series of spaces in the petrous part of temporal bone
2- Membranous inner labyrinth : continuous epithelial lined set of cavities within the bony labyrinth

Question 18

What is the perilymph

Answer 18

Fluid flowing within the bony labyrinth in the inner ear

Question 19

What is endolymph

Answer 19

Fluid flowing within the membranous labyrinth in the inner ear

Question 20

The inner ear is divided into which two sensory regions

Answer 20

1- Vestibular apparatus : balance posture , movement

2- Coclea : hearing

Question 21

What comes together to form the vestibule

Answer 21

Utricle and saccule

Question 22

The vestibular apparatus is composed of what

Answer 22

2 semicircular canals and vestibule ( utricle and saccule )

Question 23

What are the ion features of the endolymph

Answer 23

In membranous labyrinth: contains high K+ and low in Na+/ Ca+

Question 24

What are the ion features of the perilymph

Answer 24

In bony labyrinth High Na+ and low in K+/Ca+

Question 25

Difference between ion potential , especially K between the perilymph and endolymph is necessary for what

Answer 25

Proper conduction of current

Question 26

What are the utricle and saccule function

Answer 26

Detect linear acceleration/deceleration and perceive direction of gravity .

Question 27

What are the semicircular canals function

Answer 27

Detect rotational movement of head and body. Senses deviation of head form anatomical position

Question 28

The specialized sensory region in the utricle and saccule where linear movement is detected is called?

Answer 28

Macula

Question 29

In the endolymph how is movements perceived ( in inner ear )

Answer 29

Via specialized hair cells

Question 30

What is CN is the vestibulocochlear nerve

Answer 30

CN8

Question 31

The specialized sensory region in the semicircular canals where movement is detected is called?

Answer 31

Ampulla which contains the hair cells

Question 32

Explain the composition of the cochlea

Answer 32

Spiral bony canal with a central bony axis known as the modiolus, Modiolus contains spiral ganglion and cochlear nerve.

Question 33

What is the cochlear duct ( aka Scala Media )

Answer 33

Endolymph filled part of membranous labyrinth that runs up the middle of the bony spiral

Question 34

Cochlear duct divides cochlea into ...

Answer 34

3 Parallel chambers.

Question 35

What are the Cala vestibuli and Scala tympani

Answer 35

Perilymph chambers above and below the cochlear duct. | Vestibule is above, Tympani is below.

Question 36

Where is sound detected in the cochlea

Answer 36

Via hair cells in the organ of cortisones in the Cochlear duct

Question 37

Where does the organ of cortisones sit

Answer 37

On the basilar membrane of the cochlear duct

Question 38

Is the stria vascular vascular or avascular

Answer 38

Vascular

Question 39

What is the Organ of Corti composed of

Answer 39

1- Hair cells : inner and outer | 2- Phalangeal ( outer ) & pillar ( inner ) cells : support cells causing stiffness for when pulled

Question 40

The outer hair cells of the organ of cortisones are stuck to the

Answer 40

Tectorial membrane

Question 41

Where is the tectorial membrane

Answer 41

Rests over the organ of cortisones & is medially attached to the modiolus

Question 42

What are the stereocilia

Answer 42

On the surface of inner and outer hair cells that insert hair cells to tectorial membrane e

Question 43

What is the function of the outer hair cells

Answer 43

When stimulated pull on the tectorial membrane but the singular inner hair cell is the one that triggers hearing

Question 44

Explain the mechanism of hearing ( generally from beginning to end )

Answer 44

1- Vibrations of ear drum transferred to ossicles and to oval window 2- Vibrations enter perilymph of Scala vestibuli as a pressure wave 3- pressure wave passes through vestibuli membrane into endolymph of cochlear duct 4 - through the basilar membrane into the perilymph of the scar tympani 5 - then dissipates through round window of cochlea

Question 45

Explain role of hair cells in hearing

Answer 45

1- Shearing effect occurs between basilar membrane and tectorial membrane due to vibrations in perilymph and endolymph 2- sterocilia inserted in tectorial membrane are deflected ( bend ) 3- Causes outer hair cells to react by contracting ( electromotility ) which contracts tectorial membrane that shakes inner hair cells 4- stimulates inner hair cells which activated neurotransmitters that stimulate cochlear nerve 5- impulse travels to auditory cortex via cochlear nerve

Question 46

Where do high frequency sounds cause maximal vibration

Answer 46

Basila remembrance at base of cochlea

Question 47

Where do low frequency sounds cause maximal vibration

Answer 47

Basilar membrane at apex of cochlea

Question 48

Amplitude discrimination ( loudness ) depends on what

Answer 48

Degree of displacement of basilar membrane e