Anatomy of the Ear Flashcards Preview

ESA 4 - Head and Neck > Anatomy of the Ear > Flashcards

Flashcards in Anatomy of the Ear Deck (97):
1

What is the ear? 

The organ of hearing and balance

2

Where is the ear found? 

Within the petrous part of the temporal bone 

3

What does the petrous part of the temporal bone constitute?

\A large portion of the lateral area of the skull 

4

What does the petrous part of the temporal bone house? 

The cavities of the ear

5

What are the components of the temporal bone?

  • Squamous part
  • Petromastoid part
  • Tympanic plate
  • Styloid process

 

6

What does the petromastoid part of the temporal bone contain? 

The middle and inner ear

7

What does the upper surface of the petromastoid part of the bone form?

Part of the floor of the middle and posterior cranial fossae

8

What is the part of the petromastoid part that forms the posterior cranial fossa is pierced by? 

The internal acoustic meatus 

9

What does the internal acoustic meatus transmit? 

Facial and vestibulocochlear cranial nerves

10

Describe the inferior surface of the petromastoid part of the temporal bone? 

Irregular

11

What does the inferior surface of the petromastoid part of the temporal bone contain? 

The carotid canal

12

What is the purpose of the carotid canal? 

Transmits the internal carotid artery

13

What is the mastoid process?

A large palpable landmark to which several muscles are attachedf

14

What is the cavity of the mastoid antrum? 

A prolongation of the cavity of the middle ear

15

What extends into the mastoid process? 

The cavity of the mastoid antrum, by intercommunicating air cells

16

What is the clinical significance of the communication between the mastoid antrum and the mastoid process?

Middle ear disease can spread by this route to cause mastoiditis

17

What does the tympanic plate consist? 

Most of the external acoustic meatus

18

What does the free outer border of the tympanic plate do?

Provides attachment for the cartilage of the external ear

19

What does the tympanic plate do medially? 

Fuses with the petrous part of the temporal bone

20

What does the external ear consist of? 

  • Pinna/auricle
  • External acoustic meatus (ear canal)
  • Lateral surface of tympanic membrane

21

What is the functional of the external ear? 

Collects, transmits, and focuses sound waves onto the tympanic membrane

22

What does the action of the external ear on the tympanic membrane cause? 

The membrane to vibrate

 

23

Draw a picture of the pinna/auricle

24

Describe the pinna

Cartilaginous and covered with skin

25

What is true of the elastic cartilages of the pinna?

They are arranged in a number of curved ridges

26

What is the outer rim of the ear called? 

The helix

27

What is the small flap of cartilage of the ear called? 

The tragus

28

What does the tragus do? 

Guards the external acoustic meatus

29

What is the earlobe? 

A fatty structure

30

What is the external acoustic meatus? 

A skin-lined cul-de-sac

31

What shape is the external acoustic meatus? 

Sigmoid shape

32

What is the clinical relevance of the sigmoid shape of the external acoustic meatus? 

Need to pull ear up and back to straighten when examining

33

How long is the external acoustic meatus?

2.5cm 

34

Describe the external acoustic meatus

  • Outer 1/3 cartilaginous tube
  • Inner 2/3 bony canal

 

35

Where does the external acoustic meatus lie? 

In the temporal bone

36

What is the external acoustic meatus lined by? 

Skin

37

What is the purpose of the self cleaning function of the external acoustic meatus? 

Keep pathway clear

38

What facilitates the self cleaning function of external acoustic meatus? 

Arrangement of hairs and production of wax by the cartilaginous part 

39

What does the cartilaginous part of the external acoustic meatus secrete?

Cerumen

40

What is cerumen?

Modified sebum 

 

41

What does cerumen do? 

Affords protection to the delicate meatal skin

42

What forms wax?

Discarded cells of the skin together with cerumen

43

What is the function of wax?

  • Prevents objects entering deeper into the ear canal
  • Aids desquamation and skin migration out of canal

 

44

How can the external ear be visualised? 

An otoscope

45

What does the fibrous tympanic membrane mark?

The border between the external and middle ear

46

How is the tympanic membrane arranged? 

As a shallow cone with its apex pointing medially

47

Is the fibrous tympanic membrane transparent or opaque? 

Neither, it is translucent

48

What is the result of the tympanic membrane being translucent? 

It allows visulisation of some structures within the middle ear, including the malleus

49

What is attached to the malleus? 

The apex of the eardrum 

50

What is the pars tensa? 

The taut surface area of the tympanic membrane

51

Draw a diagram of the tympanic membrane

52

What is the result of the pars tensa being stretched? 

It vibrates in relation to airwaves as they hit the eardrum 

53

What is the pars flaccida? 

The loose connective tissue above the malleus

54

What is the handle of malleus? 

Where the first ossicle is attached to the tympanic membrane

55

What does the middle ear, or tympanic cavity contain? 

Ossicles

56

What do ossicles do? 

Transmit vibrations from the tympanic membrane to the inner ear in the petrous part of the temporal bone

57

What are the names of the ossicles? 

  • Malleus
  • Incus
  • Stapes

 

58

What is the handle of the malleus attached to? 

The tympanic membrane

59

What does the body of the malleus articulate with? 

That of the incus

 

60

What does the incus articulate with? 

Stapes

61

What do the stapes articulate with? 

The bony labyrinth of the internal ear

62

Where does the stapes articulate with bony labyrinth of the internal ear? 

At the oval window

63

What are the articulations of the ossicles by? 

Synovial joints

64

What do the articulations of the ossicles of the ear serve to do? 

Relay vibrations encountered by the tympanic membrane to the internal ear

65

What is the function of the ossicles? 

Amplify and concentrate sound energy from the eardrum to the oval window

66

What does the oval window run into? 

The epitympanic cavity

67

What does the middle ear communicate with anteriorly? 

The nasopharynx

68

How does the middle ear communicate with the nasopharynx? 

Via the pharyngotympanic (Eustachian) tube

69

What is the Eustachian tube part of? 

The upper respiratory tract

70

What is the clinical relevance of the Eustachian tube? 

It is a potential route for infection to spread to the middle ear

71

What does the Eustachian tube allow for? 

  • Equalisation of air pressure between middle ear and atmosphere 
  • Important in ventilation and drainage of mucus from the middle ear

 

72

What is the equilisation of air pressure between middle ear and atmosphere necessary for? 

Transfer of sound energy to internal ear

 

73

What state is the Eustachian tube usually in? 

Closed

74

How is the Eustachian tube intermittently opened? 

By the pull of attached palate muscles when swallowing

75

What does the middle ear communicate with posteriorly? 

Mastoid air cells

76

What is the inner ear also known as? 

Labyrinth

77

What does the inner ear consist of? 

A series of channels hollowed out of the petrous temporal bone surrounding the membranous labyrinth

78

What does the membranous labyrinth contain? 

Fluid called endolymph 

79

What does the perilymph seperate? 

The bony and membranous labyrinths

80

What does the labyrinth contain? 

  • Vestible 
  • Semicircular ducts and canals
  • Cochlea
  • Spiral organ of Corti

 

81

What is the vestible involved in? 

Maintaining our sense of position and balance

82

What does the vestible contain? 

  • Utricle
  • Saccule
  • Three semicircular canals

 

83

What do the utricle and saccule contain? 

Receptors that respond to rotational acceleration and static pull of gravity

84

What are the semicircular ducts and canals? 

Components of the balance system

85

What does the semicircular ducts and canals communicate with? 

Vestible

86

How are the semicircular ducts and canals arranged? 

Perpendicular with each other

87

What do the semicircular ducts and canals contain? 

Receptors that respond to rotational acceleration in three different planes

88

What is the cochlea? 

A fluid filled tube

89

What sets up movements of fluid into the coclear? 

Movements at the oval window

90

What do waves of fluid cause in the cochlea? 

Movement of special sensory cells within the cochlear duct which fire action potentials 

91

What is the cochlea the clinical site of? 

Sensorineural hearing loss

92

What does the cochlear contain? 

The cochlear duct

93

What does the cochlear duct accommodate? 

The spiral organ of Corti

94

What is the cochlear concerned with? 

Hearing

95

How is the cochlear duct associated with hearing? 

It converts sound vibration into electrical signals (action potentials) which is perceived as sound

96

What does the spiral organ of Corti contain? 

The receptors of the auditory apparatus

97

How is vibration created by sound waves at the tympanic membrane translated into electrical signal in the vestibulocochlear nerve? 

  1. Vibration of the ossicles (stapes at the oval window) sets up vibrations/movement in the cochlear fluid
  2. Sensed by nerve cells in the cochlear duct (part called the spiral organ of Corti)
  3. Movement of these receptors in organ of Corti trigger action potentials in CN VIII

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