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Neurological, neuromuscular and musculoskeletal disease > PBL 43 > Flashcards

PBL 43 Flashcards

1
Q

What are glaucomas?

A

A group of eye diseases characterised by optic nerve damage that can lead to irreversible loss of vision

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2
Q

What is the leading cause of blindness worldwide?

A

Cataracts

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3
Q

What causes glaucoma? (Pathophysiology)

A

Imbalance in production and drainage of aqueous humor

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4
Q

Aqueous humor is produced by what?

A

Ciliary body behind the iris in the posterior chamber

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5
Q

The build up of fluid in the eye causes an increased pressure which causes damage to what?

A

Optic nerve

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6
Q

What is the difference between primary and secondary glaucoma?

A

Primary is when the cause is unknown, secondary is when the cause is known

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7
Q

What are possible causes of secondary glaucoma?

A
  • Infection
  • Inflammation
  • Tumours
  • Large cataracts
  • Cataract surgery
  • Drugs
  • All of ^ keep the fluid from draining freely, which leads to increased pressure and optic nerve damage
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8
Q

What are the 2 types of glaucoma?

A
  1. Open-angle

2. Closed-angle

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9
Q

Explain the rate of open-angle glaucoma (acute vs chronic)

A

Chronic, develops slowly

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10
Q

Explain the cause of open-angle glaucoma

A

Trabecular meshwork is clogged, the canals are not visibly blocked, but drainage through them is still inadequate, this explains the slow onset nature

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11
Q

What are the symptoms of open-angle glaucoma

A
  • Gradual vision loss –> Peripheral vision loss first then central
  • Development of blind spots/patches of vision loss which grow larger and merge over months to years
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12
Q

Explain the rate of closed-angle glaucoma (acute vs chronic)

A

Acute, medical emergency

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13
Q

Explain the cause of closed-angle glaucoma

A

The iris is forced against the trabecular meshwork, which closes the anterior chamber angle, blocking drainage.

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14
Q

Explain the symptoms of closed-angle glaucoma

A
  • Sudden vision loss/blurring
  • Red eye
  • Severe eye/head pain
  • Nausea/vomiting
  • People can lose vision as quickly as 2 to 3 hours after symptom onset
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15
Q

Risk factors for glaucoma

A
  • Age older than 40
  • African ethnicity
  • FHx
  • Nearsightedness (open-angle glaucoma)
  • Farsightedness (closed-angle glaucoma)
  • Diabetes
  • High blood pressure
  • Long term corticosteroid use
  • Previous eye injury or surgery
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16
Q

Treatment for glaucoma

A
  • Beta-blockers = inhibit the ciliary epithelium beta-receptors to reduce aqueous humor production
  • Alpha 2-AR agonists = produce vasoconstriction and reduce aqueous humor production
  • Carbonic anhydrase inhibitors = decrease production of aqueous humor
  • Prostaglandin analogues = increased uveoscleral outflow
  • Miotics = increased trabecular outflow
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17
Q

What is a cataract?

A

A clouding (opacity) of the lens of the eye that causes a progressive, painless loss of vision

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18
Q

Explain the cause of cataracts (pathophysiogy)

A

Proteins and fibers in the lens begin to break down, causing vision to become hazy or cloudy

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19
Q

Risk factors for cataracts

A
  • Trauma
  • Prolonged corticosteroid use
  • Prolonged X-ray exposure / UVB
  • Diabetes
  • Nutrition
  • Smoking
  • Alcohol use
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20
Q

Signs and symptoms of cataracts

A
  • Seeing halos and starbursts around lights (glare)
  • Needing more light to see well
  • Problems distinguishing between dark blue and black
  • Blurred vision
  • Colours seeming more yellow and less vibrant
  • Mild double vision (LESS COMMON)
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21
Q

Prevention of cataracts

A
  • Consistently wearing eye-glasses or sunglasses with a coating to filter UV light
  • Not smoking
  • Reducing alcohol consumption
  • If diabetic, keeping blood sugar controlled
  • Eating a diet high in vitamin C, vitamin A and substances known as carotenoids (dark leafy vegetables such as spinach)
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22
Q

Treatment of cataract

A
  • Eyeglasses and contact lenses to improve vision

- Surgery to remove the cataract and place an intraocular lens

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23
Q

What are the three layers of the eye?

A

Fibrous layer
Vascular layer
Neural layer

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24
Q

What constitutes the fibrous layer of the eye?

A
  • Cornea

- Sclera

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25
Q

What constitutes the vascular layer of the eye?

A

Iris
Ciliary body
Choroid

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26
Q

What constitutes the neural layer of the eye?

A

Retina

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27
Q

What is the role of the ciliary body?

A

Control the shape of the lens (ciliary processes contract and relax) and contribute to formation of aqueous humor in the eye

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28
Q

What is the light detecting component of the eye?

A

The retina

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29
Q

The retina is composed of 2 layers, what are they?

A

Pigmented (outer) layer

Neural (inner) layer

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30
Q

Which layer of the retina contains photoreceptors?

A

The neural layer

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31
Q

The centre of the retina is marked by an area known as the …

A

Macula

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32
Q

The macula contains a depression called the … , which has a high concentration of light detecting cells and is repsonsible for … … …

A

Fovea centralis

High acuity vision

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33
Q

What is the anterior chamber of the eye located between?

A

The cornea and the iris

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34
Q

What is the posterior chamber of the eye situated between?

A

The iris and the ciliary processes

35
Q

Where does aqueous humor drain?

A

Through trabecular meshwork at the base of the cornea, near the anterior chamber (INTO SHLEMM’S CANAL)

36
Q

Vascular supply to the eye?

A

Ophthalmic artery, a branch of the internal carotid

Superior and inferior ophthalmic veins

37
Q

What are the extraocular muscles of the eye?

A
  1. Levator palpebrae superioris
  2. Superior rectus
  3. Inferior rectus
  4. Medial rectus
  5. Lateral rectus
  6. Superior oblique
  7. Inferior oblique
38
Q

What is the action and innervation of levator palpebrae superioris?

A

Action – elevates the upper eyelid

Innervation: CN3

39
Q

What is the action and innervation of the superior rectus?

A

Action: Main movement is elevation. Contributes to adduction and medial rotation of the eyeball

Innervation: CN3

40
Q

What is the action and innervation of the inferior rectus?

A

Action: main movement is depression. Also contributes to adduction and lateral rotation of the eyeball

Innervation: CN3

41
Q

What is the action and innervation of medial rectus?

A

Action: ADDucts the eyeball

Innervation: CN3

42
Q

What is the action and innervation of the lateral rectus?

A

Action: ABDucts the eyeball

Innervation: CN6 (LR6, SO4, R3)

43
Q

What is the action and innervation of the superior oblique?

A

Action: depresses, abducts and medially rotates the eyeball

Innervation: CN4

44
Q

What is the action and innervation of the inferior oblique?

A

Action: Elevate, abducts and laterally rotates the eyeball

Innervation: CN3

45
Q

What is the main role of the ciliary body and the iris?

A

To adjust the amount of light that goes in and out of the eye

46
Q

What is the role of miosis and mydriasis?

A

Complementary systems which help focus images on the back of the eye

47
Q

Explain miosis

A
  • Pupil constriction
  • Iris sphincter is active
  • Iris dilator is relaxed
  • Reponse to light increase
  • Parasympathetic control
  • Relaxed state
48
Q

Explain mydriasis

A
  • Pupil dilation
  • Iris sphincter is relaxed
  • Iris dilator is active
  • Response to light decrease
  • Sympathetic control
  • Elevated: emotional/aroused state
  • Lets in more light
49
Q

Sympathetic control of the eye leads to …

A

Dilation

50
Q

Parasympathetic control of the eye leads to…

A

Constriction

51
Q

How do rods and cones work?

A

They are sensitive to and absorb light, transducing light signals into electrical signals which then pass to the other layers towards the ganglion cell axons, which send off axons to the optic nerve and the brain

52
Q

Cones are more sensitive in … light

A

Bright

53
Q

Rods are mainly used for … light

A

Dim light for night vision

54
Q

Cones are found in the … of the eye whereas rods are found in the … of the eye

A
  • Center

- Periphery

55
Q

SIgnals from different types of cone are compared to differentiate what?

A

Colour

56
Q

The external ear is divided into two parts?

A

Auricle

External acoustic meatus which ends at the tympanic membrane

57
Q

What is the function of the auricle?

A

Capture and direct sound waves towards the external acoustic meatus, to convert acoustic energy to kinetic energy

58
Q

The external acoustic meatus is what shape?

A

Sigmoid shaped

59
Q

What is the function of the tympanic membrane/ear drum?

A

Vibrates in response to sound pressure waves and thus transmits sound energy from the ear canal to bones of the middle ear

60
Q

Vasculature of the external ear?

A

External carotid artery which branches into the:

  1. Posterior auricular artery
  2. Superficial temporal artery
  3. Occipital artery
  4. Maxillary artery
61
Q

Nervous supply to the ear?

A

Greater auricular nerve (branch of the cervical plexus)

Lesser occipital nerve (branch of the cervical plexus)

Auriculotemporal nerve (branch of the mandibular nerve)

Branches of the facial and vagus nerves

62
Q

The middle ear spans from?

A

The tympanic membrane to the lateral wall of the inner ear

63
Q

What is the function of the middle ear?

A

Transmit vibrations from the tympanic membrane to the inner ear via the auditory ossicles

64
Q

What is the middle ear divided into?

A

Tympanic cavity

Epitympanic recess

65
Q

What is found within the tympanic cavity?

A

The three auditory ossicles: malleus, incus, stapes

66
Q

What is the role of the auditory ossicles?

A

Transmit sound vibrations through the middle ear

67
Q

What are mastoid air cells and what is their role?

A

They are air-filled spaces in the mastoid process of the temporal bone

Role: Act as a buffer system, releasing air into the tympanic cavity when the pressure is too low

68
Q

What are the two protective muscles of the middle ear?

A

The tensor tympani

Stapedius

69
Q

What is the role of the middle ear protective muscles? ACOUSTIC REFLEX

A

They contract in response to LOUD noise, inhibiting the vibrations of the malleus, incus and stapes, to reduce transmission of sound to the inner ear.

70
Q

The inner ear houses the vestibulocochlear organs, what are its two main functions?

A
  1. Convert mechanical signs from the middle ear into electrical signals, which can transfer information to the auditory pathway in the brain
  2. To maintain balance by detecting position and motion
71
Q

The inner ear has 2 main components, what are they?

A

Bony labyrinth

Membranous labyrinth

72
Q

What constitutes the bony labyrinth?

A

Cochlea
Vestibule
Semi-circular canals

73
Q

What is the name of the fluid found within the structures of the bony labyrinth?

A

Perilymph

74
Q

Wha is the name of the fluid found within the membranous labyrinth?

A

Endolymph

75
Q

There are 3 semi-circular canals, what are they called?

A

Anterior, lateral and posterior

76
Q

What do they semi-circular canals contain and what are they responsible for?

A

Semi-circular ducts, responsible for balance

77
Q

The inner ear is innervated by which nerve?

A

CN8

78
Q

What are the 2 types of hearing loss?

A

Conductive

Sensorineural

79
Q

Explain conductive hearing loss

A

Problem conducting sound waves through the outer ear, eardrum or middle ear

80
Q

How can a problem with solely air conduction be fixed?

A

Circumvention by bone conduction which take sound through the petrous part of the temporal bone straight to the middle ear

81
Q

What are common causes of conductive hearing loss?

A
  • Earwax
  • Otitis externa & media
  • Perforated ear drum
  • Fluid in middle ear
  • Damage to bones of middle ear
82
Q

What is sensorineural hearing loss?

A

Problem in the cochlea (Organ of Corti), vestibulocochlear nerve or auditory cortex of the brain

  • A PROBLEM WITH BOTH AIR AND BONE CONDUCTION
83
Q

What are common causes of sensorineural hearing loss?

A
  • Congenital
  • Presbycusis
  • Inflammatory disease e.g measles, mumps, meningitis, syphillis
  • Ménières disease
  • Ototoxc drugs (gentamycin, furosemide, cisplatin, some NSAIDs)
  • Physical trauma
  • Noise-induced
  • Benign tumour on auditory nerve
84
Q

Why is otitis media so common in children?

A

The eustachian tube is smaller and more horizontal, therefore it can be more easily blocked by conditions such as large adenoids and infections.

  • Until the eustachian tube changes in size and angle as the child grows, children are more susceptible to otitis media

Neurological, neuromuscular and musculoskeletal disease (36 decks)

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