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B8 Ocular Anatomy > B8 Optic Nerve > Flashcards

B8 Optic Nerve Flashcards

1
Q

Approx how many RGC reside in RGCL in adult retina?

A

~1.2-2.2 million

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2
Q

The RGC axons of the retina come together forming what structure?

A

Optic nerve

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3
Q

Majority of optic nerve fibers have a diameter of ___________ micrometer, while a small percent have diameters ranging ________-_________ micrometers.

A

1 micrometer

2-10 micrometers

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4
Q

CN II (optic nerve) is a nerve fiber tract of the __________________________. Thus, it is prone to many of the same neurological diseases such as multiple sclerosis.

A

Central nervous system

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5
Q

When viewing the ONH what do we need to note/observe?

A
  • cup-to-disc ratio
  • central retinal blood vessels (artery and vein)
  • ONH color
  • size of ONH
  • OD and OS ONHs symmetrical?
  • presences of lamina cribosa
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6
Q

Name of the foramen when optic nerve is not present.

A

Posterior scleral foramen

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7
Q

Central retinal blood vessels typically emerge from

A

Nasal side of cup

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8
Q

Cup-to-disc ratio compares diameter of cup with overall diameter of optic disc to assess…

A

Changes to neuroretinal rim thickness over time

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9
Q

ISN’T rule

A 
Order of rim tissue thickness
(Thickest)
- Inferior
- Superior
- Nasal
- Temporal 
(Thinnest)
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10
Q

The intraocular portion of the optic nerve is divided into 2 parts:

A

1) Pre-laminar

2) Laminar

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11
Q

Pre-laminar portion of Optic Nerve consists of __________ & ____________ layers.

A

Retinal

Choroidal

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12
Q

Retina layer of pre-laminar portion of ON contains the __________ ___________, the convergence of the RGC axons.

A

Optic disc

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13
Q

Choroidal layer of the pre-laminar portion of ON is at level of ____________ _________ and it’s outermost portion is the beginning of the ____________ ___________ which is continuous as scleral tunic outside ONH.

A

Choroidal tunic

Lamina cribosa

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14
Q

Laminar portion of Optic nerve consists of ___________ layer, which is a continuous tunic of eyeball. This the layer in which the ___________ ____________ resides.

A

Scleral

Lamina cribosa

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15
Q

Intraocular portion of ONH can be further divided into 3 layers. Name them:

A

1) Retinal
2) Choroidal
3) Scleral (Lamina cribosa)

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16
Q

CN II is approx _____ cm in length and can be divided into 4 parts. Name them:

A

4-5 cm

1) Intraocular
2) Intraorbital
3) Intracanalicular
4) Intracranial

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17
Q

With increased IOP, in some glaucoma patients, the lamina cribosa will

A

Bulge posteriorly and, if severe enough, could possibly pinch down on CN II

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18
Q

Optic disc is located in what layer (retinal, choroidal, or scleral)?

A

Retinal

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19
Q

Intraocular optic nerve: glial borders

A

1) Meniscus of Kuhnt
2) ILM of Elschnig
3) Border Tissue of Elschnig
4) Border Tissue of Jacoby
5) Intermediary Tissue of Kuhnt
6) ILM of retina

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20
Q

Glial plaques (astrocytes) that line optic cup.

A

Meniscus of Kuhnt

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21
Q

Peripheral continuation of Meniscus of Kuhnt that lines surface of neuroretinal rim.

A

ILM of Elschnig

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22
Q

Collagen separating choroid from bundles of ON fibers

A

Border Tissue of Elschnig

22
Q

Glial tissue situated btw Border Tissue of Elschnig and bundles of ON fibers. It merges with Intermediary Tissue of Kuhnt.

A

Border Tissue of Jacoby

24
Q

Glial borders: Meniscus of Kuhnt, ILM of Elschnig, Intermediary Tissue of Kuhnt, and ILM of Retina are located in what layer?

A

Retinal layer

24
Q

Glial tissue that separates outer retina from bundles of ON fibers.

A

Intermediary Tissue of Kuhnt

25
Q

Glial borders: Border Tissue of Elschnig and Border Tissue of Jacoby are located in what layer?

A

Choroidal layer

26
Q

Remnant of Meniscus of Kuhnt tissue surrounding the Hyaloid Vasculature during development. Is this something to worry about?

A

Bergmeister’s Papilla; no, just document

26
Q

Formed by footplates of Muller cells, continuous with ILM of Elschnig.

A

ILM of Retina

27
Q

Anterior counterpart to Bergmeister’s Papilla, located in most anterior portion of cloquet’s canal, just posterior to posterior surface of lens, and is (more or less) common.

A

Mittendorf’s dot

More

28
Q

In some patients we will see excess myelination of _______________ . Is this something to worry about?

A

RGC axons; no, just document

29
Q

_____________________ form thick columns that keep the axonal fibers organized into bundles in the optic nerve.

A

Astrocytes

30
Q

Intraorbital portion of ON extends ____ mm from sclera to apex of the orbit.

32
Q

Myelination of optic nerve is (Pre or Post) laminar.

33
Q

Central retinal artery runs along ON, then at about ______ cm behind eyeball it pierces _________ and _____________ sheaths of ON, entering eyeball via lamina cribosa.

A

1.25 cm
Dural
Arachnoid

34
Q

Myelin (increases or decreases) in diameter in the retrobulbar portion of optic nerve.

35
Q

The presence of ________ and ____________ is responsible for the incr in diameter of ON from 1.5mm to 3-4mm.

A

Myelin

Oligodenricytes

36
Q

Parts of the ON that reside outside of eye are surrounded by a meningeal sheath, called ________ ________ _______, and is continuous with meninges surrounding brain.

A

Optic nerve sheath

37
Q

The optic nerve sheath is comprised of 3 layers that fuse the sclera. Name them most superficial to deepest.

A

1) dura mater (tough)
2) arachnoid (delicate)
3) pia mater (vascular)

38
Q

Bilateral swelling of optic disc caused by elevated ICP w/in subarachnoid space.

A

Papilledema

39
Q

Papilledema is presents typically with __________________, ______________________, __________________, and ______________________.

A
  • blurred margins of optic disc
  • engorged venous blood vessels
  • small peripapillary hemes
  • loss of spontaneous venous pulsation (vein more susceptible due to artery have strong muscular tunic)
40
Q

Pseudopapilledema caused by _____________________________, in which are composed of small conglomerates of mucopolysaccharides and proteinaceous material that become _______________ with increasing age.

A

ON drusen; calcified

41
Q

True or false: pseudopapilledema is caused by incr in ICP.

42
Q

Intracanalicular portion of ONH is approx ____mm in length. Passes through ________ wing of sphenoid bone via ______ _______ and is accompanied by _____________ artery, which sits inferolateral to ON.

A

5mm
Lesser
Optic canal
Ophthalmic

44
Q

Intracanalicular portion of CN II is surrounded by orbital fat, lying ___________ to ciliary ganglion,
___________ to LR, and
___________ to CRA.

A

Medial
Medial
Superomedial

44
Q

LFT Out

A

Structure OUTSIDE of annular tendon of Zinn:

  • Lacrimal nerve
  • Frontal nerve
  • Trochlear nerve (CN 4)
  • Ophthalmic veins (superior and inferior)
45
Q

Intracranial portion of ON, accompanied with ___________ artery, is approx _____ mm in length and after leaving the optic canal, passes w/in __________________ space of brain where it will merge w/ nerve fibers from contralateral optic nerve at the __________ _________.

A

Ophthalmic
10 mm
Subarachnoid
Optic chiasm

46
Q

The optic chiasm is located in the floor of ____________ _______________.

A

3rd ventricle

47
Q

Vascular supply to Optic Nerve

A

A: internal carotid, ophthalmic artery (main), CRA and it’s collateral branches (supplying Intraorbital portion), retinal capillaries (supplying retinal layers of ON), choroidal capillaries via long and short posterior ciliary (forming the arterial circle of zinn-haller) arteries (supplying choroidal layers of ON), pial plexus (supplying orbital and canalicular portions of OH)

V: central retinal vein

48
Q

Scleral crescent

A

Thinning of retinal tissue that results in the scleral tissue showing through

48
Q

When ON inserted obliquely, it’s called what? Do we worry?

A

Tilted disc; no, just document

49
Q

Peripapillary crescent exposes what layers. Would you include this area in C-to-D ratio?

A

RPE and/or Choriodal; no

51
Q

Peripapillary atrophy sometimes seen in what disease?

53
Q

True or False: Muller cells reside within the ONH.

A

False; only in retinal tissue

54
Q

Inferior notch of visible lamina cribosa; one of 1st signs of glaucoma.

A

Glaucomatous Inferior notch

B8 Ocular Anatomy (1 decks)

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