A05 Assessment of Vision and Hearing Flashcards Preview

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Flashcards in A05 Assessment of Vision and Hearing Deck (39)
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1
Q

Where does the visual system start and end?

A
  • It starts at the rods and cones of the retina.

- It ends at the gyri on either side of the calcarine sulcus of the occipital lobe.

2
Q

What is meant when the visual pathway is said to be retinotopically arranged?

A

The regions of the retina are represented in discrete regions throughout the tract.

3
Q

List the layers of the eye from superficial to deep.

A

1 - Sclera.

2 - Uveal tract.

3 - Retina.

4
Q

Describe the structure of the sclera.

A
  • It is a continuation of the dura mater surrounding the optic nerve.
  • At its most anterior pole it is transparent, forming the cornea.
5
Q

Describe the structure of the uveal tract.

A
  • It is mostly choroid, which is the vascular layer of the eye.
  • Anteriorly, it becomes the ciliary body (which contains the muscles which moves the lens), and the stroma of the iris.
6
Q

Describe the structure of the retina.

A
  • It is an outgrowth of the CNS.
  • The outermost part of the retina which is in contact with the choroid is the retinal pigment epithelium.
  • The innermost layer of the retina is the neural retina.
7
Q

What is the lens?

A

The transparent, biconvex elastic disc behind the uveal tract that separates the anterior 1/5 of the eye from the posterior 4/5.

8
Q

What maintains the position and shape of the eye?

A

Intraocular pressure that is generated by production of aqueous and vitreous humour.

9
Q

What is a cataract?

A

Opacity of the lens.

10
Q

Where are aqueous and vitreous humour stored?

A
  • Aqueous humour is contained within the anterior and posterior chambers.
  • Vitreous humour is contained within the postremal / vitreous chamber.
11
Q

Where are the anterior and posterior chambers?

A
  • The anterior chamber is between the cornea and the uveal tract.
  • The posterior chamber is between the uveal tract and the lens.
12
Q

Which layer of the eye accounts for most refraction of light?

Why is this?

A
  • The cornea.

- Because the refractive index of the aqueous humour, vitreous humour and lens are all very similar.

13
Q

What is the function of the lens?

A

It adjusts the focus of the eye for near and far objects by action of the ciliary muscles.

14
Q

What is the advantage of the refraction that arises from the cornea?

A

It enables peripheral vision.

15
Q

Define accommodation.

A

Changing the focus from viewing one object to another.

16
Q

What is the effect of contraction of the ciliary muscles?

A

They cause the anterior surface of the lens to bulge, causing the eye to accommodate to near subjects.

17
Q

What is the pupil?

A

The densely pigmented aperture in the middle of the iris.

18
Q

List the main components of the ear.

List the main contents of each component.

A

1 - Outer ear, consisting of:

  • Auricle (visible part of the ear).
  • External auditory canal.

2 - Tympanic membrane (eardrum).

3 - Middle ear (tympanic cavity), consisting of:

  • Auditory ossicle bones.
  • Eustachian tube.

4 - Inner ear, consisting of:

  • Cochlea.
  • Vestibule.
  • Semicircular canals.
19
Q

What is the eustachian tube?

What is its function?

A
  • The canal that connects the middle ear to the nasopharynx.

- It controls the pressure within the middle ear, making it equal with the pressure outside the body.

20
Q

What is the barrier between the external and middle ear?

A

The tympanic membrane.

21
Q

Through which passage does sound travel before vibrating the tympanic membrane?

A

The external acoustic meatus.

22
Q

Which group of bones vibrate as a result of vibration of the tympanic membrane?

Which bones are included in this group of bones?

A
  • The auditory ossicles.

- The malleus, incus and stapes.

23
Q

Which structure vibrates as a result of vibration of the auditory ossicles?

A

A membrane which vibrates the perilymph.

24
Q

What is perilymph?

Where is it located?

A
  • Extracellular fluid.

- It is found within the scala tympani and scala vestibuli of the cochlea.

25
Q

What results from the action of the waves in the perilymph?

A

The spiral organ of Corti transmits action potentials via the cochlear part of CNVIII.

26
Q

List the components of CNVIII.

A

1 - The vestibular nerve.

2 - The cochlear nerve.

27
Q

What is the function of the vestibular nerve?

A

To transmit information regarding the position of the head in space.

28
Q

What is the function of the cochlear nerve?

A

To transmit auditory information from the cochlea.

29
Q

What is the optic disk?

What is the significance of the optic disk?

A
  • The point of exit for ganglion cell axons leaving the eye.

- It is the cause of the blind spot, since no photoreceptors, interneurones or ganglion cells are present here.

30
Q

Define myopia.

A

Near-sightedness.

31
Q

Define hyperopia.

A

Long-sightedness.

32
Q

List the muscles that control the size of the pupils.

A

1 - DIlator pupillae.

2 - Sphincter pupillae.

33
Q

What is the direct pupillary light reflex?

A

Constriction of the pupil when it is directly illuminated.

34
Q

What is the consensual pupillary light reflex?

A

Constriction of the pupil when the other eye is illuminated.

35
Q

Define hemianopia.

A

Blindness in half of the visual field of either or both eyes.

36
Q

Define homonymous.

A

Affecting the same part of the field of each eye.

37
Q

Define heteronymous.

A

Affecting different parts of the field of each eye.

38
Q

List 2 arteries that supply the ear.

Which component(s) of the ear does each artery supply?

A

1 - External carotid artery (middle and outer ear).

2 - Labyrinthine artery (inner ear).

39
Q

What is the function of the inferior colliculus?

A
  • It is the principal midbrain nucleus of the auditory pathway and receives input from several peripheral brainstem nuclei in the auditory pathway, as well as inputs from the auditory cortex.
  • It is a point of integration and enables spatial localisation.