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ANAT3004 > Eye and Orbit > Flashcards

Eye and Orbit Flashcards

1
Q

What are the 7 bones of orbit?

A
  1. Frontal
  2. Zygomatic
  3. Maxillary
  4. Lacrimal
  5. Sphenoid
  6. Ethmoid (orbital bone)
  7. Palatine bone
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2
Q

What are the openings of the orbit? (9)

A
  1. Superior orbital fissure
  2. Inferior orbital fissure
  3. Infraorbital groove and foramen
  4. Optic foramen
  5. Lacrimal canal
  6. Anterior and posterior ethmoid foramina
  7. Zygomatico orbital foramina
  8. Supraorbital foramen
  9. Trochleal fovea or spine - half way between supraorbital notch/foramen and frontolacrimal suture
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3
Q

What is the superior orbital fissure crossed by?

A
  1. Oculomotor
  2. Branches of CNV/1 (lacrimal, frontal, nasociliary),
  3. Trochlear (CNIV)
  4. Abducens (CNVI)
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4
Q

What is the infraorbital groove and foramen crossed by?

A

Maxillary/infraorbital nerve CNV/2

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5
Q

What is the trochleal fovea or spine for?

A

Superior oblique muscle

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6
Q

What is the orbit lined with?

A

Orbital periosteum

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7
Q
  1. What are the spaces between the eye, nerve muscles and blood vessels filled with?
  2. What is a feature of orbital fascia?
A
  1. Orbital fascia

2. Coarsely loculated fat

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8
Q

What are the extrinsic muscles of the orbit?

A
  1. Levator palpebrae superioris
  2. Rectus muscles
  3. Obliques (superior and inferior)
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9
Q

Where does the levator palpebrae superioris arise? What is its function? What passes superior to it?

A

Lesser wing sphenoid, above rectus superiors and optic canal.
Raises upper eyelid
Frontal nerve

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10
Q

Where do the rectus muscles originate? Where do the rectus muscles insert?

A

Originate in part from tendinous ring around optic nerve.

They insert anterior to equator of eyeball.

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11
Q

Where do the superior, inferior and medial recti arise?

A

Tendinous ring around optic nerve

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12
Q

How many heads does the lateral rectus have? Where do they come from?

A

Two.

From lateral part of tendinous ring and from lateral margin of orbital fissure.

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13
Q

Where do the obliques insert?

A

Further back, posterior to equator of eyeball.

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14
Q

Where does the superior oblique insert?

A

Between superior and lateral rectus

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15
Q

Where does the inferior oblique insert?

A

Between inferior and lateral rectus

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16
Q

What movement are the medial and lateral recti responsible for?

A

Side to side

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17
Q

What movement are the superior and inferior recti responsible for?

A

Elevation and depression

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18
Q

What movement is the superior oblique responsible for?

A

Down and out

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19
Q

What movement is the inferior oblique responsible for?

A

Turns eye up and out.

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20
Q

What is the palpebral area comprised of? (7)

A
  1. Tarsal plates/tarsus (eyelids)
  2. Tendon of levator palpebrae superioris
  3. Lateral and medial palprebral ligaments
  4. Orbital septum is a fascial sheet attached to periosteum of orbital rim and levator tendon
  5. Eyelids are lined with conjunctiva which is continuous with cornea
  6. Sebaceous tarsal glands empty into the free margin of the eyelid. The oily secretion spreads out over the tear film and contributes to its stability.
  7. Cilia (eyelashes) also have small sebaceous glands
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21
Q

Where are the lacrimal glands located?

A
  1. Mostly in superolateral orbit

2. Some in eyelid lateral to tarsal plate between conjunctiva and pelpebral fascia

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22
Q

What are tears a mix of? (3) What gland is responsible for producing each one?

A
  1. Serous (Lacrimal gland and accessory serous glands in conjunctiva)
  2. Mucus (Conjunctival glands)
  3. Sebaceous (Sebaceous tarsal glands - eyelids)
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23
Q

Where do tears drain?

A

Into the medial corner of the eye and from there into the nasolacrimal duct via lacrimal canaliculi ( one per eyelid, above and below plica semilunaris) and lacrimal sac.

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24
Q

What are the wall of the eyeball?

A
  1. Fibrous outer coat (sclera/cornea)
  2. Vascular intermediate coat - uvea –> includes choroid and anterior parts of ciliary body and iris
  3. Retina
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25
Q

What is the main refractive apparatus of the eye?

A

Cornea

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26
Q

What are the two parts of the retina?

A
  1. Sensory retina

2. Non-sensory retina

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27
Q

What does the sensory retina consist of?

A

Thick inner layer consisting of photoreceptors (rods and cones) and other layers of neurons.

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28
Q

Where is the pigment epithelium and what is its function?

A

Behind the rods and cones and phagocytoses worn out parts of photoreceptors

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29
Q

What are the special areas of the sensory retina?

A

Optic disc at the site of the entry of the optic nerve and a region adjacent to the optic disc where all elements of the retina except cones are reduced - the macula/ fovea - region of greatest visual acuity

30
Q

Where is the non-sensory retina?

A

Forms the posterior parts of ciliary body and iris

31
Q

What are the parts of the eyeball?

A
  1. iris
  2. Lens
  3. Ciliary body
32
Q

What is the function of the iris?

A

Variable aperture to control amount of light onto retina

33
Q

What is the structure of the iris?

A

Anterior part - uvea

Posterior part - non-sensory retina (just 2 cells thick - unlike thick sensory retina - 10 layers)

34
Q

What is the iris responsible for?

A

Has ability to both contract and expand:

  1. Contraction - circular muscle around pupil - controlled by parasympathetic fibres of oculomotor origin
  2. Dilation via radial muscle extending outwards from pupil - controlled by sympathetic innervation
35
Q

What is the lens comprised of? What is it covered with?

A

2 cell layers thick, anterior cuboidal, posterior consists of elongated cells. Acellular capsule

36
Q

What are the functions of the ciliary body?

A
  1. Production of aqueous humour

2. Accomodation for far and near vision

37
Q

What is the structure of the ciliary body?

A
  1. Anterior part - uvea

2. Posterior part - non-sensory retina

38
Q

What are the lends and ciliary body responsible for?

A

Accomodation - accommodates for near and far vision

39
Q

What is the lens attached to the ciliary body by?

A

Zonary fibres

40
Q

What controls the sphincter contraction on ciliary body?

A

Parasympathetic fibres

41
Q

What happens when the sphincter contracts?

A
  1. Less tension on zonule fibres

2. Less pull on lens which rounds out/becomes less flat

42
Q

How many layers does the sensory retina have?

A

10

43
Q

What is the sensory retina’s junction with non-sensory retina called?

A

Ora serrata

44
Q

Describe the layers of the sensory retina from outer to inner.

A
  1. Pigment epithelium (1 cell thick) is outside rods and cones and phagocytoses worn out components of rods and cones
  2. Rods and Cones are in outer retina adjacent to posterior pigment epithelium
45
Q

What are the different types of humours?

A
  1. Aqueous

2. Vitreous

46
Q

Where is the aqueous humour located? What is it produced by? Where is it transported? What does it pass through

A

Posterior and anterior chamber of eyeball
Produced in folds of ciliary body
Posterior chamber
Passes through pupil and into anterior chamber

47
Q

Where does aqueous humour drain?

A

Drains from eye into scleral venous sinus (canal of Schlemm)

48
Q

Where is the vitreous humour located? What is it comprised of?

A

Vitreous chamber, behind lens

Fluid connective tissue

49
Q

What is the optic nerve comprised of?

A

Contains predominantly sensory afferents that are the central processes of the ganglion cells in the deepest part of the sensory retina. These pass across the inner surface of the retina and through the optic disc to become the optic nerve. There are also some efferent fibres that play a role in light adaption and reflex.

50
Q

What is the pupillary reflex? What happens if parasympathetic supply is compromised?

A

Light into one eye then both pupils should contract as retina sends fibres into optic tracts of both sides.
Sphincter is slow

51
Q

What is the corneal reflex? What nerves are responsible for this?

A

Blinking when the cornea is touched.

i) Afferent via opthalmic nerve
ii) Efferent via orbicularis oculi (facial nerve)

52
Q

What supplies both the orbit and eyeball?

A

Opthalmic artery

53
Q

What are the branches of the opthalmic artery?

A
  1. Central artery of retina
  2. Orbital branch
  3. Cutaneous supratrochlear and supraorbital branches
54
Q

What does the central artery supply?

A

Only supply to retina, no anastomosis between branches

55
Q

What does the orbital branch supply?

A
  1. Lacrimal gland
  2. Ethmoid and frontal sinuses
  3. Part of the nasal cavity
  4. Extrinsic muscles of eye
  5. Iris and ciliary body
  6. Choroid
  7. Eyelids
56
Q

What does the cutaneous supratrochlear and supraorbital branches supply?

A

Forehead

57
Q

What are the venous drainage of the orbit and eyeball?

A
  1. Retinal veins - converge on optic disc and enter optic nerve as central vein of retina. Drain into superior opthalmic vein –> cavernous sinus
  2. Inferior opthalmic vein drains orbit –> cavernous sinus. Thus both opthalmic veins have linkages with pterygoid venous plexus
58
Q

What are the cranial nerves to orbit? What do they all pass through?

A
  1. Occulomotor
  2. Opthalmic
  3. Trochlear
  4. Abudcent
    All pass through cavernous sinus along with internal carotid carrying carotid sympathetic plexus.
59
Q

What fibres are transferred in the cavernous sinus?

A

Sympathetic fibres are transferred in the cavernous sinus from cartoid plexus to other nerves crossing cavernous sinus.

60
Q

What extrinsic eye muscles does the occulomotor nerve innervate?

A

To all but 2 muscles of orbit
Superior division - supplies superior rectus and levator palpebrae superioris
Inferior division - to inferior and medial rectus, inferior oblique

61
Q

What extrinsic eye muscles does the trochlear nerve innervate?

A

Superior oblique

62
Q

What extrinsic eye muscles does the abducent nerve innervate?

A

Lateral rectus

63
Q

What are the major branches of the opthalmic nerve?

A
  1. Lacrimal
  2. Frontal
  3. Nasociliary
64
Q

What does the lacrimal nerve innervate? Where is it located?

A

Lacrimal gland and skin

Lateral

65
Q

How are the frontal nerves divided? Where does the frontal nerve pass? Where is it located?

A

Cutaneous branches are supratrochlear (more medial and smaller), supraorbital (more lateral, larger and usually forms two branches –> medial and lateral either in orbit or on forehead). Passes over superior surface of levator palpebrae superioris
Central

66
Q

Where is the nasociliary nerve located?

A

Deep and medial

67
Q

Where is the infratrochlear branch located?

A

Just medial to inner corner of the eye

68
Q

What does the autonomic innervation of iris and ciliary body?

A

Opthalmic nerve carry parasympathetic fibres from other nerves to iris and ciliary body and to lacrimal gland. Sympathetic fibres also travel these branches (derived from internal carotid plexus)

69
Q

What is parasympathetic innervation required for?

A

Contract sphincters of pupil and ciliary body
Contraction of ciliary ciliary muscle –> decrease tension on zonule fibres connecting ciliary body and lens resuling in a decrease in the diameter of the ciliary body

70
Q

What is sympathetic innervations required for?

A
  1. Dilate pupil

2. Vasomotor (constriction) to blood vessels

71
Q

Where do parasympathetic and sympathetic fibres pass?

A

Through sclera to reach iris and ciliary body

72
Q

What do ciliary nerves supply?

A

Sensory fibres to cornea.

ANAT3004 (12 decks)

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