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Ocular Anatomy > Lecture 2: Orbital Anatomy > Flashcards

Lecture 2: Orbital Anatomy Flashcards

1
Q

what are the 7 bones that make up the orbit?

A

frontal, sphenoid, ethmoid, zygomatic, maxilla, lacrimal, and palatine

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2
Q

what are the first body hairs produced during embryological development?

A

eyebrows

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3
Q

eyebrows aid in was expressions?

A

facial

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4
Q

the eyebrows are innervated by what CN?

A

CN 7 (facial)

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5
Q

what is another term for eyelids?

A

palpebrae

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6
Q

what are the 4 functions of the eyelids?

A
  • Protect the globe
  • Move tears towards punctum to drain
  • Spread tears over the ocular surface
  • House structures that produce an oily layer of the tear film (meibum)
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7
Q

what is the limbus?

A

The corneal limbus is the border of the cornea and the sclera (the white of the eye).

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8
Q

what is the bulbar conjunctiva?

A

This portion of the conjunctiva covers the anterior part of the sclera (the “white” of the eye).

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9
Q

what is the fornix?

A

The fornix of the conjunctivae refers to loose arching folds connecting the conjunctival membrane lining the inside of the eyelid with the conjunctival membrane covering the eyeball.

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10
Q

what is palpebral conjunctiva?

A

The part of the conjunctiva, a clear membrane, that coats the inside of the eyelids.

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11
Q

what is the lacrimal punctum? What lid has the punctum? Where do they open into?

A

A small aperture that is located in a slight tissue elevation (the lacrimal papilla) at the junction of the lacrimal and ciliary portions of the eyelid margin.

Both upper and lower lids have a punctum. The puncta are turned toward the globe and normally can be seen only if the eyelid edge is everted slightly. Each punctum opens into a tube, the lacrimal canaliculus.

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12
Q

what is the eyelid margin?

A

The eyelid margin describes the portion located at the edge of the eyelid. It is the juncture of the conjunctiva and the skin

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13
Q

what is the palpebral fissure?

A

The elliptic space between the medial and lateral canthi of the two open eyelids.

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14
Q

what is the medial/ lateral canthus?

A

The medial and lateral ends/angles of the palpebral fissure (where the eyelids meet)

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15
Q

what are meibomian glands?

A

Tiny oil glands that line the margin of the eyelids (the edges which touch when the eyelids are closed).

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16
Q

why are meibomian glands important?

A

These glands secrete oil which coats the surface of our eyes and keeps the water component of our tears from evaporating (drying out).

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17
Q

the normal adult eye is roughly the size of what? (object)

A

the size of a quarter

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18
Q

what is the diameter of a normal adult eye?

A

24-25 mm (1 inch)

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19
Q

an additional 1 mm is equal to how many diopters?

A

3 diopters

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20
Q

what structure is homologous to the nictitating membrane (3rd eyelid)?

A

Plica semilunaris

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21
Q

the plica semilunaris allows for what type of movement?

A

lateral movements of the eye

22
Q

where is the caruncle located?

A

Located medial to plica

semilunaris

23
Q

is the caruncle an avascular or vascular structure?

A

It is a highly vascular pink nodule

of modified skin

24
Q

what does the caruncle contain?

A

a large nest of accessory lacrimal and sebaceous glandular tissue

25
Q

what is the caruncle covered in? And what does that contain?

A

Covered with epithelium that contains goblet cells

26
Q

what is the order of the tear drainage system?

A

Lacrimal gland

Lacrimal duct Eye

Lacrimal punctum

Lacrimal canaliculus

Common canaliculus

Lacrimal Sac

Nasolacrimal duct

Inferior meatus (Valve of Hasner)

27
Q

what mm numbers are associated with the canaliculus, nasolacrimal sac, and nasolacrimal duct?

A 
Canaliculus (8mm)
Nasolacrimal Sac (10 mm)
Nasolacrimal duct (12 mm)
28
Q

contraction of what muscle expands the sac? what type of pressure is created?

A

Contraction of Orbicularis muscle expands the sac, creates negative pressure, and pulls tears from canaliculus into the nasolacrimal sac.

29
Q

The negative pressure generated in the sac pulls tears from the canaliculus into what structure?

A

nasolacrimal sac

30
Q

relaxation collapses the sac; the tears are pushed where?

A

nasolacrimal duct

31
Q

what structure prevents retrograde movement of fluid from the nasal cavity?

A

Valve of Hasner

32
Q

where is the center of the pupil located?

A

slightly nasal and inferior

33
Q

the eye is composed of 3 layers. what are they? what is each layer composed of?

A
  1. fibrous tunic (cornea and sclera)
  2. vascular tunic - uvea (iris, ciliary body, and choroid)
  3. Neural tunic (retina)
34
Q

what is the principal function of the choroid?

A

To provide blood supply to the outer

the layer of the retina

35
Q

what are two other functions (other than the principal function) of the choroid?

A

• Thermoregulatory role

• Absorption of light by choroidal
pigment aids vision by preventing unwanted light from reflecting back through the retina

36
Q

how many chambers does the eye have? what are they?

A
  1. anterior
  2. posterior
  3. vitreous
37
Q

what is each chamber of the eye filled with? amount?

A
  1. AnteriorChamber
    Filled with aqueous humor (200 ul)
  2. Posterior Chamber
    Filled with aqueous humor (50 ul)
  3. Vitreous Chamber
    Filled with the gel-like vitreous body
38
Q

what is the safest point of entry into the eye for vitreoretinal surgical procedures?

A

Pars Plana

The pars plana portion of the ciliary body is much thinner and less vascularized than the pars plicata

39
Q

what is the diameter of the fovea centralis?

A

Hz dia 1.5mm

40
Q

what structure has the highest concentration of cones in the retina (199,000- 300,000/sq mm)?

A

fovea centralis

41
Q

what is the capillary free zone?

A

0.4-0.5mm of the fovea

It allows light to pass through unobstructed into the photoreceptor outer segment

42
Q

what is the foveola?

A

center of foveal depression

43
Q

what is the clivus?

A

the curved wall of foveal depression leading

to foveola

44
Q

what is the clinical implication of the fovea?

A

+ or - Foveal Reflex

45
Q

the lens is encased and suspended by what?

A

in a capsular bag and suspended within the eye by zonules (or zonular fibers).

46
Q

what is accommodation?

A

the lens changes shape to focus for close up or distance vision

47
Q

what is the clinical implication of accommodation?

A

Presbyopia = loss of accommodation

48
Q

what is tenon’s capsule?

A

A sheet of dense connective tissue encases the globe.

49
Q

where does tenon’s capsule lie?

A

It lies between Conjunctiva and episclera.

50
Q

what is the conjunctiva?

A

a thin, translucent mucus membrane that covers the anterior sclera from the limbus

  • anteriorly it lines the eyelids
51
Q

the tenon’s capsule acts as a barrier to prevent what?

A

the spread of orbital infections to the globe

52
Q

sub-tenon’s injection is administered to treat what?

A

post-cataract surgery inflammation

Ocular Anatomy (15 decks)

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