Lecture 8 Eyes and Ears Flashcards Preview

Musculoskeletal Anatomy II > Lecture 8 Eyes and Ears > Flashcards

Flashcards in Lecture 8 Eyes and Ears Deck (72)
Loading flashcards...
1
Q

What are the three layers of the eyeball

A

Sclera, choroid, retina

2
Q

What is the sclera

A

dense, white CT that the extrinsic muscles of the eye attach to

3
Q

What is the cornea

A

Continuous with sclera, it is a clear protective layer over the anterior chamber

4
Q

What part of the eye has the greatest refractive index

A

The cornea

5
Q

What is the purpose of having different refractive indices in different parts of the eye

A

The goal is to bend the image so that it hits the best location for viewing

6
Q

How does the sclera get nutrients

A

Because it is avascular, it derives nutrients from the aqueous humor via diffusion

7
Q

Where is the caruncula lacrimalis

A

In the medial corner of the eye

8
Q

What is the conjunctiva

A

Thin, clear mucus membrane that covers the anterior, external part of the eyes and lines the inner eyelids

9
Q

What is the function of the conjuntiva

A
  1. It produces fluid that bathes the eye to keep it moist and nourished
  2. It contains MALT and secretes IgA!
10
Q

What is the choroid

A

Layer of numerous anastomosing blood vessels

11
Q

What are the two jobs of the ciliary body

A
  1. control lens 2. produce aqueous humor
12
Q

What is the function of the iris

A

Control pupil size with the sphincter pupillae and dilator pupilla

13
Q

What is the innervation of the sphincter pupillae and dilator pupillae

A

Sphincter pupillae has parasympathetic innervation from the Edinger-Westphal nucleus, and the dilator pupillae has sympathetic innervation from the superior cervical ganglion

14
Q

What is the innervation of the cornea

A

Sensory innervation from the trigeminal nerve (CN V), Opthalmic branch (V1)

15
Q

What are the layers of the cornea

A

Epithelium, collagen, and endothelium

16
Q

What is a good test for corneal abrasions

A

Drop some fluorescein in their eye and then shine a black light. Abrasions will fluoresce green

17
Q

What is the lens composed of

A

prismatic cells AKA lens fibers

18
Q

What is accommodation

A

As things get closer to your face, the pupils narrow and the lens thickens to adjust the optical power and keep the object in focus

19
Q

What are the Zonules of Zinn

A

Fibrous strands that connect the ciliary body to the lens

20
Q

What is presbyopia

A

Changes in the elasticity of the lens that makes it harder to focus on objects close to the eye.

21
Q

What is in the anterior chamber

A

Aqueous humor

22
Q

What is aqueous humor

A

Ultra-filtrate of the blood similar to CSF

23
Q

What is the function of the aqueous humor

A

Provides nutrients to cornea and assists in immune response

24
Q

What is a common pathology involving the aqueous humor

A

If drainage slows or production is greatly increased, fluid and pressure can build up. In Glaucoma, blindness results from this process damaging the optic nerve

25
Q

What is the retina composed of

A

Pigmented receptors and neurons and ganglion cells

26
Q

What is seemingly inefficient about the retina

A

The receptors are pointed posteriorly so that light has to reflect off the pigmented epithelium before hitting the rods and cones

27
Q

What is the macula lutea

A

Area with the highest density of cones

28
Q

What is the fovea centralis

A

Pit in the center of the macula lutea

29
Q

What is the function of cones

A

To detect color (red, blue, and green) and provide acute vision

30
Q

What is the function of rods

A

The are more sensitive to light, provide peripheral vision, and do not respond to red light. This means you can use a red hued light to look at your secret battle plans at night without blinding yourself. Awesome.

31
Q

What is an essential vitamin for both rods and cones

A

The vitamin A derivative: retinal

32
Q

Are rods or cones more plentiful

A

Rod are more numerous. They have relatively fewer neurons tho, which accounts for why cones are responsible for acuity.

33
Q

Why is optic ‘nerve’ a misnomer

A

Because it is really an extension of the brain, it should be called a tract

34
Q

What surrounds the optic nerve

A

meninges

35
Q

How far does the subarachnoid space extend

A

To the lamina cribrosa

36
Q

<p>What kinds of cells surround the axons in the optic nerve</p>

A

<p>Astrocytes and oligodendrocytes</p>

37
Q

What is papilledema

A

Increased CSF limits venous return from retina and causes edema under the optic disc

38
Q

What types of proteins are in the vitreous body (humor)

A

hyaluronic acid and type II collagen fibrils

39
Q

What is the function of the vitreous body

A

Keeps the shape of the eyeball and keeps the retina in place

40
Q

What is the hyaloid canal

A

vestige of hyaloid artery used to nourish embryonic lens

41
Q

What causes ‘floaters’

A

blood and cell debris that is too large to be cleared by phagocytes

42
Q

What are the four steps of the visual pathway

A
  1. light hitting the retina is transformed into nerve impulses by rods and cones
  2. impulses travel through optic nerve to optic chiasm
  3. signals travel to lateral geniculate body of the thalamus
  4. signals travel through the optic radiations to the primary visual cortex of the occipital lobes
43
Q

What does the Abducens Nerve (CN VI) innervate

A

Lateralis rectis

44
Q

What does the troclear nerve (CN IV) innervate

A

superior oblique

45
Q

What is the action of the suerior oblique

A

internally rotates, depresses and abducts the eye (down and out)

46
Q

What are the structures of the outer ear

A

pinna and auditory meatus (so designed to funnel sound to the tympanic membrane)

47
Q

What is earwax (cerumen)

A

Secretion from modified sebaceous glands that protects the ear from irritation and infection

48
Q

What are the ossicles

A

Malleus, incus, and stapes

49
Q

What types of articulations are between the ossicles

A

Synovial!

50
Q

What are the muscles of the middle ear

A

tensor tympani attaches to the malleus and stapedius attaches to the stapes. Both contract to reduce movement of the ossicles

51
Q

What innervates the inner ear

A

vestibulocochlear nerve

52
Q

How does sound transfer from the middle to the inner ear

A

movement of the stapes at the oval window moves the perilymph in the scala vestibuli

53
Q

What is perilymph and where is it found

A

filtrate with a high sodium content in the scala vestibuli

54
Q

What is endolymph and where is it found

A

filtrate with high potassium content in the scala media (cochlear duct)

55
Q

Where is the organ of Corti located

A

In the cochlear duct along its entire length

56
Q

How are waves in the perilymph converted to electric signals

A

Movements in the perilymph vibrate the endolymph, basilar membrane and organ of corti. Hair cells in the organ of Corti are moved which starts an AP

57
Q

How does the ear perceive different pitches

A

The basilar membrane is thick and stiff near the oval window and becomes more flexible further down the cochlea and is thus affected by lower pitches further away

58
Q

What nerve transmits impulses from the ear

A

The cochlear division of the vestibulocochlear nerve

59
Q

What is the order of structures auditory nerve impulses go through

A
  1. cochlear nucleus 2. superior olivary nucleus 3. inferior colliculus 4. thalamus 5. primary auditory cortex (in the temporal lobe)
60
Q

What coordinates nerve impulses from both ears

A

The inferior colliculus processes information from both ears to determine location of sound

61
Q

What are some components of balance

A

Visual system (see the ground), pressure and proprioception (feel the ground under your feet), and vestibular

62
Q

What are the 3 parts of the vestibule

A

saccule, utricle, and 3 semicircular canals all filled with endolymph

63
Q

how does the vestibular system work

A

Hair cells generate nerve impulses when moved by gravity or motions of the head

64
Q

What are otoliths

A

Crystalline structures composed of gelatinous matrix and calcium carbonate on the tips of hair cells that amplifies the effects of gravity or motion (makes them top heavy). For detecting linear acceleration and found only in the utricle or saccule.

65
Q

What are the semicircular canals composed of

A

They are bone lined with periosteum and containing endolymph

66
Q

How are the semicircular canals arranged

A

In such away that they correspond to the 3 dimensions of space (x, y, and z)

67
Q

What are the ampullae

A

enlargement at the base of each semicircular canal

68
Q

What is the function of the ampullae

A

Sense rotational movement with the semicircular canals

69
Q

What is BPPV

A

Benign paroxysmal positional vertigo is a condition in which the patient is overcome by a sudden sensation of spinning

70
Q

What causes BPPV

A

Thought to be from an otolith from a utricle or saccule that entered the semicircular canals and activates the hair cells

71
Q

How is BPPV diagnosed

A

Patient history and Dix-Hallpike maneuver

72
Q

How is BPPV treated

A

Epley maneuver or Semont maneuver