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Ocular Anatomy > Lecture 1/19 > Flashcards

Lecture 1/19 Flashcards

1
Q

vitreous humor occupies what percent of the internal aspect of the eye?

A

2/3

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2
Q

volume of the vitreous humor

A

3.9 cc

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3
Q

big depression on anterior side of vitreous called

A

patellar fossa

or hyloid fossa

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4
Q

vitreous bounded posteriorly by the

A

retina

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5
Q

vitreous bounded anteriorly by the

A

ciliary body, zonules, and posterior capsule of the lens

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6
Q

functions of vitreous

A
  • maintains shape of the eye
  • supports the retina up against its tissue
  • materials exchange (diffusion)
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7
Q

strongest attachment of the vitreous is where?

A

anterior at the ora serrata and pars plana (about 6mm)

-called virtual base of Salzmann

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8
Q

what is the vitreous base of Salzmann?

A

strongest attachment of the vitreous anteriorly at the ora serrata and pars plana

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9
Q

where is the posterior strong vitreous attachment?

A

around optic nerve head

peripapillary

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10
Q

what is the peripapillary?

A

strong attachment of the vitreous around the optic nerve head

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11
Q

what is the weaker anterior attachment of the vitreous?

A

periphery of posterior lens (ring of 8-9mm) called hyaloideo-capsular

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12
Q

where is the hyaloideo-capsular attachment of the vitreous?

A

periphery of posterior lens about 8-9mm in diameter

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13
Q

where is the capillary space of Berger

A

area of potential space (non-attachment) in the center of hyaloideo-capsular ligament

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14
Q

hyaloideo-capular ligament clinical importance

A

in cataract surgery- can pull vitreous with this ligament, which can make contact with anterior chamber which is bad

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15
Q

microanatomy of vitreous is

A

semifluid, 99% water and a little hyaluronic acid and collagen fibers

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16
Q

purpose of the micro anatomy of the vitreous

A

-medium for substance exchange and structure

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17
Q

vitreous is what type of tissue?

A

modified connective tissue- a matrix of collagen fibers with water in between

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18
Q

primary embryological divison

A

hyaloidean vitreous

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19
Q

hyaloid artery runs:

A

through middle of embryonic vitreous canal (supplies anterior structures during development)

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20
Q

where is the anterior dilation of the hyaloidean vitreous

A

just behind (posterior) to the lens at that time

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21
Q

where is the posterior dilation of the hyaloidean vitreous

A

around the optic nerve

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22
Q

blood vessel in the hyaloidean vitreous is

A

hyaloid artery

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23
Q

what happens to the hyaloid artery as embryonic development continues?

A

it disintegrates because other circulation is taking place that will supply the anterior portion of the eye

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24
Q

the hyaloid artery disintegrating leaves:

A

a canal through the center of the adult vitreous called Cloquet’s canal

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25
Q

secondary vitreous called

A

definitive vitreous

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26
Q

definitive vitreous is:

A

the adult vitreous, what you are born with (the main mass)

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27
Q

tertiary zonules are called:

A

zonules (anatomists used to think they were composed of vitreous)

28
Q

what are zonules formed by?

A

the ciliary body

29
Q

what structure is at the edge of the vitreous

A

an envelope with cells underneath (100 microns)

30
Q

location of cells at the edge of the vitreous

A

within a thin zone of 100 microns

31
Q

shape and name of the cells at the edge of the vitreous

A

round cells called hyalocytes

32
Q

what type of cell are hyalocytes

A

connective tissue type of cell which have macrophages

33
Q

source of hyalocytes

A

cells come from the ciliary body

34
Q

3 categories of ocular muscles

A
  • intrinsic
  • extrinsic
  • accessory
35
Q

intrinsic ocular muscles

A

iris (smooth), ciliary body

36
Q

extrinsic ocular muscles

A

EOMs (4 recti, 2 oblique)- voluntary

37
Q

accessory ocular muscles

A

eyelids

38
Q

EOMs are what kind of muscle

A

striated, voluntary

39
Q

compared to other skeletal muscles, the nerve and vascular supply in EOMs is

A

more rich

40
Q

what is a motor unit

A

the ratio of number of nerves to muscle fibers

41
Q

what is the EOM motor unit ratio and how does it compare to other striated muscle

A

EOMs have 1:6 ratio which is low, and other striated muscle has 1:100- 1:150 ratio range

42
Q

what does the EOM low motor unit ratio mean?

A

EOMs have finer control

43
Q

fibers sizes are ____ in EOMs compared to other skeletal muscles

A

smaller

44
Q

what is the anatomical origin?

A

site where the muscle is attached to the bone (blending of the tendon or origin and covering of the bone, periosteum)
-strong

45
Q

what is the physiological origin?

A

where the muscle acts from (mechanical)

46
Q

5 of the 6 EOMs have their origin at:

A

the apex of the orbit

all except IO

47
Q

the 4 rectus muscle’s origins form what at the apex?

A

a ring called the annulus of Zinn

48
Q

the annulus of Zinn ring is formed from a special blending of what 3 tissues

A
  • tendon of origin
  • periorbital (periosteum) tissue
  • dura mater (meninges)
49
Q

the hole in the middle of the Annulus of Zinn is the:

A

oculomotor foramen

50
Q

nerves and vessels can come in to the orbit through what routes?

A

directly through the superior orbital fissure or through the oculomotor foramen

51
Q

what are the 2 aspects of the Annulus of Zinn?

A
  1. superior tendon of Lockwood (upper 1/2)

2. inferior tendon of Zinn (lower 1/2)

52
Q

superior tendon of lockwood (upper 1/2) contains

A
  • superior rectus

- upper halves of medial and lateral rectus

53
Q

inferior tendon of zinn (lower 1/2) contains:

A
  • inferior rectus

- lower halves of the medial and lateral rectus

54
Q

anatomical origin of superior oblique

A

on sphenoid near optic foramen

55
Q

physiological origin of superior oblique

A

fovea trochlearis (anterior on the medial wall)

56
Q

what are the 2 types of anatomical insertions

A

primary and secondary

57
Q

what are the primary insertions for the 4 recti?

A

insert at the anterior portion of the eye and it forms a spiral (spiral of Tillaux)

58
Q

in the spiral of Tillaux, how far is each recti muscle away from the limbus

A

MR: 5.5 mm
IR: 6.0 mm
LR: 7.0 mm
SR: 8.0 mm

59
Q

what is the primary insertion for the superior oblique

A

posterior quadrant, lateral and superior (1/4)

60
Q

what is the primary insertion for the inferior oblique

A

on the posterior quadrant, lateral and inferior (1/4)

61
Q

what is the purpose of secondary insertions?

A

stabilization, mechanical support

62
Q

list 3 types of secondary insertions

A
  • recurrent fibers
  • lateral expansion
  • check ligaments
63
Q

path of recurrent fibers

A

run from belly of the muscle down to the sclera

64
Q

path of lateral expansions

A

go sideways from the tendon to the sclera (helps prevent wobble)

65
Q

path of check ligaments

A

connects from tendon to bone (solid insertion)

Ocular Anatomy (20 decks)

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