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Yr 2 - Control > SDL - Eye and Ear > Flashcards

SDL - Eye and Ear Flashcards

1
Q

Label structures indicated in the following diagram, showing a cross section through the eyeball.

A
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2
Q

In life, what occupies the area marked A on the above diagram?

A

Aqueous humour - found between cornea and iris

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3
Q

LList the structures through which light entering the eye passes before rreaching the retinal photoreceptors.

A

Cornea, pupil, lens, vitreous humour, retina

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4
Q

What and where is the conjunctiva?

A

The conjunctiva is the clear, thin membrane that covers part of the front surface of the eye and the inner surface of the eyelids

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5
Q

Function of the conjunctiva?

A

The conjunctiva of the eye provides protection and lubrication of the eye by the production of mucus and tears.

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6
Q

Function of the sclera?

A
  • Insertion point for muscles that move the eyeball.
  • Tough, white, fibrous tissue
  • Provides protection and form
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7
Q

Function of the iris?

A

The iris controls the amount of light that enters the eye by opening and closing the pupil. The iris uses muscles to change the size of the pupil.

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8
Q

What is the nerve supply to:

(i) the circular muscle of the iris i.e. sphincter pupillae muscle?
(ii) the radial muscle of the iris i.e. dilator pupillae muscle?
(iii) the ciliary muscle contained within the ciliary body?

A

i) CN III
ii) sympathetic fibres
iii) CN III

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9
Q

What effect does contraction of the ciliary body have upon the lens?

A

The effect of contraction is to decrease the diameter of the ring of ciliary muscle causing relaxation of the zonule fibers, the lens becomes more spherical, increasing its power to refract light for near vision.

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10
Q
  1. What are cataracts?
A

Cataracts are when the lens, a small transparent disc inside your eye, develops cloudy patches

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11
Q

As well as its involvement in controlling the shape of the lens, the ciliary body is important for the production of what?

A

Aqueous humour

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12
Q

What does the aqueous humour fill?

A

The anterior compartment of the eye (between cornea and iris)

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13
Q

Function of the aqueous humour?

A

The pressure of this fluid helps to maintain the shape of the cornea and thus the refractive properties of the eye.

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14
Q

Aqueous humor is eventually reabsorbed into the blood stream.

  1. Where does this reabsorption occur?
  2. Through which structures?
A

drains from the eye through a drainage pathway presented by trabecular meshwork and Schlemm’s canal between the cornea and iris

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15
Q

What is aqueous humour produced by?

A

Ciliary body

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16
Q

Problems with the drainage of aqueous humor can lead to glaucoma. What is glaucoma?

A

Glaucoma is a common eye condition where the optic nerve, which connects the eye to the brain, becomes damaged. It’s usually caused by fluid building up in the front part of the eye, which increases pressure inside the eye

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17
Q

List two functions of the choroid layer of the eyeball.

A
  1. Supplies the outer retina with nutrients
  2. Maintains the temperature and volume of the eye. T
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18
Q

Which part of the eye contains photoreceptors?

A

Retina

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19
Q

What 2 layers is the retina made up of?

A
  1. an outer pigment cell layer – a single layer cuboidal epithelial cells with melanin filled microvilli extending from their inner surface
  2. a multi layered neural retina
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20
Q

In the diagram below label the following:

  • pigment cell layer
  • rod cell
  • cone cell
  • bipolar cell (= first order neurons of visual pathway)
  • ganglion cell (= second order neurons of visual pathways)
  • interneurons
A
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21
Q

List three functional differences between rod cells and cone cells.

A
  • Rods:
    • are responsible for vision at low light levels (scotopic vision)
    • They do not mediate color vision
    • have a low spatial acuity
  • Cones:
    • active at higher light levels (photopic vision)
    • are capable of color vision
    • are responsible for high spatial acuity.
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22
Q

The axons of the retinal ganglion cells run over the inner surface of the retina. Where do they converge?

A

converge on the optic disc or optic papilla -> become optic nerve

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23
Q

Why is there a blind spot at the optic disc?

A

There are no photoreceptors

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24
Q
  1. How can you demonstrate the blind spot in an individual with normal vision?
A

To demonstrate its existence to yourself, close your right eye, look at the + sign below with your left eye, then move your head toward or away from the screen slowly while continuing to watch the + sign.

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25
Q
  1. What is papilloedema?
  2. What is it a sign of?
A

optic disc swelling that is secondary to elevated intracranial pressure, can be a sign of haemorrhage or brain tumour

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26
Q

Swelling of the optic disc can also occur due to other causes. Suggest two.

A

Cases with bilateral optic disc swelling are often associated with papilledema, infiltrative optic neuropathy, toxic optic neuropathy, and malignant hypertension

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27
Q

Just lateral to the optic disc of each eye is a yellow pigmented zone, the macula lutea, at the centre of which is a specialised region called the fovea. The fovea is the point on the retina at which the image of the object at the centre of the visual axis falls.

  1. The fovea is specialised for visual activity. How?
A

Contains high density specialised photoreceptors called cones

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28
Q
  1. Where do the blood vessels that supply the retinal cells lie?
A

?

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29
Q

Ophthalmoscope view of eye:

Locate the optic disc, the central retinal artery and vein and the macula lutea

A
30
Q
  1. What is a detached retina? Why is it important to repair a detached retina as rapidly as possible?
A

A detached retina is when the retina becomes loose. It needs to be treated quickly to stop it permanently affecting your sight.

31
Q

label the structures indicated in the following diagram of the ear

A
32
Q

List the structures through which sound waves entering the external ear pass before reaching the auditory receptors.

A
  1. Auricle
  2. External acoustic meatus
  3. Tympanic membrane
  4. Ossicles
  5. Oval window
  6. Cochlea
33
Q

What is the function of the tympanic membrane?

A
  • Separates external ear from middle ear
  • When sound waves reach the tympanic membrane they cause it to vibrate. The vibrations are then transferred to the ossicles in the middle ear.
34
Q

Function of the ossicles?

A
  • Vibrate to transmit/amplify sound waves into cochlea ear (from middle to inner ear)
  • Bones vibrate to amplify sound
35
Q

Function of the oval window?

A
  • Separates middle ear from cochlea of inner ear
  • Vibration of the oval window leads to movement of fluid within the cochlea and activation of receptors for hearing
36
Q

Function of the round window?

A

The round window serves to decompress acoustic energy that enters the cochlea via stapes movement against the oval window. Any inward motion of the oval window via stapes vibration leads to outward motion of the round window.

37
Q

Function of the auditory/Eustachian tube?

A
  • Drains fluids into nasopharynx
  • Ventilates the middle ear
  • Equalise pressure between external environment and pressure on the inside
38
Q
  1. The external auditory canal is lined by skin that produces ear wax. What is the wax made up of? How does it travel along the ear canal?
A
  • Earwax consists of dead skin cells, hair, and the secretions of cerumen by the ceruminous and sebaceous glands of the outer ear canal.
  • The earwax travels with slowly growing cells of your skin. Over time, the earwax moves from the inner part of your ear canal to the entrance of the canal. Jaw movement also helps the earwax move through the canal.
39
Q

The tympanic membrane is illustrated in the following diagram. Label the structures indicated by pointers.

A
40
Q
  1. What is the function of the chorda tympani (branch of the facial nerve)?
A
  • Provides taste sensation to anterior 2/3 of tongue
41
Q

Which border of the midle ear does the tympanic membrane form?

A

Lateral wall

42
Q

What type of epithelium is the middle ear lined by?

A

Respiratory epithelium

43
Q

The middle ear is connected antero-inferiorly to the nasopharynx via what structure?

A

Eustachian tube

44
Q
  1. The middle ear is connected posteriorly to the mastoid air cells. Through what opening?
A

aditus to mastoid antrum

45
Q
  1. Why are meningitis, brain abscess, and sigmoid sinus thrombosis potential complications of middle ear infection?
A
  • Infection can spread across the mastoid air cells and to the middle cranial fossa and potentially the brain
  • Internal jugular vein lies inferior to middle ear - infections of middle ear can spread to IJV and damage lining leading to thrombosis risk
46
Q
  1. Why is facial nerve damage a potential complication of middle ear infection?
A

The middle ear is traversed by the chorda tympani and facial canal

47
Q
  1. The tensor tympani and stapedius muscles are located (at least partly) in the middle ear. What is their nerve supply and what is their function?
A
  • Function: dampen loud sounds to protect ear
  • Nerve supply:
    • Stapedius: CN VII
    • Tensor tympani: CN V3
48
Q

Which part of the temporal bone is the inner ear located?

A

Petrous part

49
Q

What fluid is the bony labyrinth filled with?

A

Perilymph

50
Q

What is found within the bony labyrinth?

A

Membranous labyrinth

51
Q

What fluid is the membranous labyrinth filled with?

A

Endolymph

52
Q

The membranous labyrinth has three kinds of sensory receptor within its walls. What are they?

A
  1. Maculae - vestibular receptors
  2. Christae ampullaris - vestibular receptors
  3. Spiral organ (Organ of Corti) - auditory receptors
53
Q
  1. In which regions of the membranous labyrinth are the maculae located?
A

housed within the utricle and saccule

54
Q
  1. The maculae are concerned with what type of sensory information?
A

balance

55
Q
  1. In which regions of the membranous labyrinth are the christae ampullaris located?
A

They are found in the ampullae of each of the semicircular canals of the inner ear, meaning that there are 3 pairs in total.

56
Q
  1. What type of sensory information are the christae ampullaris concerned with?
A

sense angular acceleration and deceleration.

57
Q

Note at least three structural similarities between the maculae and the christae ampullaris.

A
  • Both are hair cell containing structures
  • ?
58
Q
  1. In which nerve do the axons of the first order sensory neurons associated with these receptors travel to the brainstem?
A

vestibular nerve

59
Q
  1. Injury to the peripheral vestibular system can cause nystagmus and vertigo. What is meant by the terms nystagmus and vertigo?
A
  • Nystagmus: a person suffers with involuntary, uncontrollable eye movements.
  • Vertigo: It’s the sensation that you, or the environment around you, is moving or spinning.
60
Q

Where is the organ of Corti located?

A

in the wall of the cochlear duct, i.e. the part of the membranous labyrinth lying within the snail-shell shaped, bony cochlea (part of the bony labyrinth).

61
Q

The bony cochlea, and its enclosed cochlear duct, spiral 2½ times around a central axis of bone. What does this central region enclose?

A

This central region encloses the spiral ganglion, made up of cell bodies of the first order auditory neurons.

62
Q

What is the spiral ganglion?

A

made up of cell bodies of the first order auditory neurons.

63
Q

label the structures indicated by pointers in the following diagram of a longitudinal section through the central axis of the cochlear:

A
64
Q

label the very simplified diagram below of the Organ of Corti

A
65
Q

Fluid movement in the inner ear, in response to sound waves, causes the basilar membrane to vibrate. How does the basilar membrane vibrate in response to frequency?

A

Each point on the basilar membrane vibrates maximally in response to sound of a particular frequency.

66
Q

What is the effect of the basilar membrane vibrating?

A

Vibration of the basilar membrane causes the hairs (stereocilia) to be deformed against the overlying, gelatinous tectorial membrane. This causes depolarisation/hyperpolarisation of the sensory hair cells and generates action potentials in the sensory nerve fibres synapsing at the base of the cells.

67
Q
  1. Which region of the basilar membrane vibrates maximally in response to sounds of
  • high frequency?
  • low frequency?
A

High frequency: base

Low frequency: apex

68
Q

Where are the cell bodies of the sensory fibres that contact the hair cells?

A

Spiral ganglion

69
Q
  1. Which cranial nerve do these first order sensory fibres join? Where does this nerve enter the brainstem?
A

The vestibulocochlear nerve (CN VIII) - enters brainstem at cerebellopontine angle

70
Q

An individual who cannot hear may have either conduction deafness or sensorineural deafness. Define these two terms.

A
  • A conductive deafness is a deficit related to an obstructed, or altered, transmission of sound to the tympanic membrane or through the ossicle chain of the middle ear.
  • Sensorineural hearing loss is a type of hearing loss in which the root cause lies in the inner ear or sensory organ (cochlea and associated structures) or the vestibulocochlear nerve (cranial nerve VIII).

Yr 2 - Control (71 decks)

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