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Block 5 Material > Anatomy - Orbit > Flashcards

Anatomy - Orbit Flashcards

1
Q

What bones form the roof and floor of the orbit?

A

Floor

  • orbital process of maxilla
  • palatine bone

Roof
-orbital part of frontal bone

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2
Q

What bones form the walls of the orbit?

A

Medial walls

  1. Orbital plate of ethmoid
  2. Frontal process of maxilla
  3. Lacrimal
  4. Sphenoid

Lateral walls

  • frontal process of zygomatic bone (ant)
  • greater wing of sphenoid (post)
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3
Q

The apex of the orbit is at the __

A

Optic canal in the lesser wing of the sphenoid

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4
Q

What separates the floor of the orbit from the lateral wall?

A

Inferior orbital fissure

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5
Q

What houses the lacrimal gland?

A

Fossa for the lacrimal gland in the orbital part of the frontal bone

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6
Q

Fissures and foramina of the orbit

A
  1. Optic canal
  2. Superior orbital fissure
  3. Inferior orbital fissure
  4. Infraorbital groove
  5. Ethmoidal foramina
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7
Q

The optic canal goes through ___ and allows for passage of ___

A

Goes through the lesser wing of the sphenoid

Allows for passage of
Optic n. (CN II)
Ophthalmic a.

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8
Q

Superior orbital fissure is located ___ and allows for passage of ___

A

Between the greater and lesser wings of sphenoid

Allows for passage of:
CN III
IV
VI
V1
Ophthalmic v.
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9
Q

Inferior orbital fissure is located ___ and allows for passage of ___

A

At the right angle to the superior orbital fissure
-between greater wing of sphenoid and maxilla

Allows for passage of 
CN V2 (maxillary n.)
Infraorbital vessels
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10
Q

Travel of the infraorbital groove?

What does it contain?

A 
Begins from inferior orbital fissure
Travels anteriorly 
Becomes enclosed in bone
Forms infraorbital canal
Opens below orbital rim as the infraorbital foramen

Contains infraorbital n. and vessels

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11
Q

Ethmoidal foramina allows for passage of __

A

Anterior and posterior ethmoidal nerves and vessels

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12
Q

____ humor is irreplaceable and more dense than ___

A

Vitreous

Aqueous

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13
Q

The aqueous humor is located in the (anterior/posterior) chamber of the eye

A

Anterior

Which is between cornea and iris

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14
Q

The posterior chamber is located between ___ and ___

A

Iris and lens

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15
Q

3 layers of the eyeball and what they contain

A
  1. Fibrous
    • sclera, cornea
  2. Vascular
    • choroid, ciliary body, iris
  3. Retinal
    • optic disc, macula, ocular fundus
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16
Q

Tough fibrous layer covering the posterior 80% of the eyeball.

The anterior part is visible as the white of the eye

A

Sclera

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17
Q

Transparent part of the fibrous layer located in the anterior part of the eye.

A

Cornea

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18
Q

The cornea is more ___ than the sclera and projects ___

A

Convex

Anteriorly

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19
Q

Blinking and tears are elicited by touching what? and innervation of what nerve?

A

Cornea

Ophthalmic n. (V1)

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20
Q

The ____ lines most of the sclera and contains a rich capillary bed, with the smallest vessels located next to the ___, which is avascular

A

Choroid

Retina

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21
Q

The ____ connects the choroid with the iris. It is both ___ and ___

A

Ciliary body
Muscular
Vascular

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22
Q

The ___ is a thin contractile diaphragm with a central aperture, the ___, for transmitting ___.

A

Iris
Pupil
Light

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23
Q

Two involuntary muscles control the size of the pupil:

  • system
  • fibers
  • action
  • speed
A

Sphincter pupillae

  • parasympathetic
  • circular fibers
  • constriction
  • fast

Dilator pupillae

  • sympathetic
  • radial fibers
  • dilation
  • slow
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24
Q

The optic part of the retina consists of 2 layers:

A
  1. Neural layer
    - light sensitive
    - continuation of the CN II
  2. Pigmented layer
    - attached to choroid
    - helps reduce scattering of light through absorption
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25
Q

During a retinal detachment, which layer of the retina becomes dislodged?

A

Neural layer only

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26
Q

Where the Optic Nerve (CN II) enters the eyeball, the retina contains the __

A

Optic disc

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27
Q

True or false:

the optic disc has photoreceptors

A

False

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28
Q

The oval-shaped area of acute vision is called the __

A

Macula

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29
Q

The posterior part of the eyeball wig its retina is called the ____.
This is where light is ___

A

Ocular fundus

Focused

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30
Q

Light traveling to the retina passes through the following structures:

A 
Cornea
Anterior chamber
Posterior chamber
Lens
Vitreous humor
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31
Q

The anterior chamber is filled with ___, which is produced by ___

A

Aqueous humor

Ciliary body

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32
Q

The posterior chamber is filled with __

A

Aqueous humor

33
Q

The lens is attached to the ciliary processes by __

A

The suspensory ligament

34
Q

Explain accommodation

A
  • passive stretching and thinning of the lens brings far objects into focus
  • sphincter like contraction of ciliary muscle relaxes the lens, bringing near objects into focus (parasympathetic)
35
Q

Layers of the eyelids, anterior to posterior

A
  1. thin skin with loose CT layer
  2. Skeletal muscle fibers
  3. Orbital septum
  4. Tarsi (dense CT, eyelid “skeleton”)
  5. Conjunctiva
  6. Muscles of superior eyelid
36
Q

Skeletal muscle fibers on the second layer of the eyelids:
Action
Innervation

A

Palpebral part of orbucularis oculi

  • involuntary (orbital part is voluntary)
  • gently close eyelid
  • innervates by CN VII
37
Q

What is the orbital septum?

Attachments?

A
  • Fibrous membrane
  • Continuous with periosteum of the orbital rim and the tarsi
  • in the upper eyelid it also attaches to levator palpebrae superioris tendon
38
Q

The superior and inferior tarsi are made of ___. Attachments?

A

Dense CT

Medially: Maxilla through Medial Palpebral ligament

Laterally: zygomatic bone through lateral Palpebral ligament

39
Q

Tarsal glands produce ___

A 
Oily secretions
Keep eyelids from sticking together 
Modified sebaceous glands
Increase viscosity of tears
Decrease evaporation
40
Q

Mucous membrane that lines the eyelids internally and reflects into the sclera superiorly and inferiorly

A

Conjunctiva

41
Q

The upper and lower pockets formed by the reflections of the conjunctiva onto the sclera are called:

A

Superior and inferior fornices

42
Q

Muscles of superior eyelid elevation

A

Levator Palpebrae Superioris

Superior Tarsal Muscle

43
Q

Origin, insertion, and innervation of levator Palpebrae superioris

A

Posterior part of Orbital roof
Superior tarsus
CN III

44
Q

Origin, insertion, and innervation of superior tarsal muscle

A

Levator Palpebrae Superioris
Superior Tarsus
Sympathetic postganglionic fibers from the superior cervical ganglion

45
Q

The lacrimal gland is located ___ in the ___ corner of the orbit

A

Anteriorly

Superolateral

46
Q

Excretory ducts carry the lacrimal fluid to the ___ of the conjunctiva

A

Superior fornix

47
Q

Lacrimal fluid that accumulates in the medial corner of the eye is drained via __

A

Superior and inferior lacrimal canaliculi

48
Q

The openings of the canaliculi are the ___, located on the ___ surface of the eyelid

A

Puncta

Posteromedial

49
Q

Innervation of the lacrimal gland

A

Production of fluid = parasympathetic through CN VII

sympathetic fibers re vasoconstrictive

50
Q

All recti muscles originate from the __ and insert on the __ part of the eyeball

A

Common tendinous ring around the Optic Nerve (annulus of Zinn)

Anterior

51
Q

Oblique muscles originate from the ___ and attach to the __ part of the eyeball

A

Orbital walls

Posterior

52
Q

Actions and innervation of:

Lateral rectus

A

Abduction

CN VI (abducens)

53
Q

Actions and innervation of:

Medial rectus

A

Adduction

CN III

54
Q

Actions and innervation of:

Superior rectus

A

Elevation
Slight adduction
CN III

55
Q

Actions and innervation of:

Inferior rectus

A

Depression
Slight adduction
CN III

56
Q

Actions and innervation of:

Superior oblique

A

When the eye is abducted:
Abduction and intortion

When the eye is adducted:
Depression

CN IV

57
Q

Origin and insertion of superior oblique

A

Sphenoid

Goes to trochlea (pulley) and bends to insert on the superior and posterior eyeball

58
Q

Actions and innervation of:

Inferior oblique

A

When the eye is abducted:
Abduction and extortion

When the eye is adducted:
Elevation

CN III

59
Q

The only extraocular muscle that originates from the anterior part of the orbit (near the lacrimal fossa) is the __

A

Inferior oblique

60
Q

The ___ is a large sensory nerve partially ensheathed with the cranial meninges

A

Optic N. (CN II)

61
Q

The optic n. passes into the orbit via the ___ and collects sensory info from the ___. It projects to the ___ geniculate nucleus of the ___

A

Optic canal
Retina
Lateral
Thalamus

62
Q

The oculomotor n. (CN III) nuclei are in the ___. The nerve exits the brain between the __ and the ___. It passes into the orbit via the ____.

A

Midbrain
Midbrain and pons
Superior orbital fissure

63
Q

The superior branch of CN III innervates the __ and ___

A

Levator Palpebrae Superioris

Superior Rectus

64
Q

The inferior branch of CN III innervates the ___, ____, and ____.

A

Medial rectus
Inferior rectus
Inferior oblique

65
Q

The _____ gives off a branch carrying preganglionic parasympathetic fibers to the ___ ganglion, which continue as ____ nerves to the sphincter pupillae muscle

A

Inferior branch of CN III
ciliary
Short ciliary

66
Q

The nucleus of CN IV is located in the ___. CN IV enters the orbit via the ___. It innervates the __

A

Midbrain
Superior orbital fissure
Superior oblique

67
Q

The nucleus of CN VI is in the ___. It enters the orbit through the ___ and innervates the ___

A

Pons
Superior orbital fissure
Lateral rectus

68
Q

CN V1 is pure ___. It divides into what 3 nerves that pass through what opening into the orbit?

A 
Sensory
Superior orbital fissure
1. Nasociliary
2. Lacrimal
3. Frontal
69
Q

Which branch off of V1 is typically first? What does it supply?

A

Nasociliary n.

Ciliary ganglion, eyeball, medial eyelids, nose, anterior cranial fossa

70
Q

What structures does the lacrimal n. supply? Frontal n.?

A

Lacrimal:
Lacrimal gland
Conjunctiva
Lateral part of upper eyelid

Frontal:
Eyelids
Conjunctiva
Forehead
Scalp
71
Q

What artery supplies most of the orbit? It follows the ___ n. to enter the orbit through the ___

A

Ophthalmic
Optic
Optic canal

72
Q

As the ophthalmic a. is passing along the lateral side of the optic n. it gives off the ___, which supplies the ___

A

Lacrimal a.

Lacrimal gland

73
Q

Position of the ophthalmic a. relative to the optic n.

A

Inferolateral but

Upon entering the orbit it crosses superior and medial

74
Q

Branches of the ophthalmic a.

A
  1. Lacrimal
  2. Central retinal
  3. Posterior ciliary (6 short and 2 long)
  4. Muscular branches (anterior ciliary)
  5. Supraorbital
  6. Ethmoidal
  7. Supratrochlear
75
Q

The floor of the orbit also receives blood supply from the ___, which passes into the orbit via the ___ and is a branch of the ___

A

Infraorbital a.
Infraorbital foramen
ECA

76
Q

Venous drainage of the orbit is through the ___ and the ___, which pass through the ___ and enter the __ sinus.

A

Superior and inferior ophthalmic veins
Superior orbital fissure
Cavernous

77
Q

The superior ophthalmic v. is formed by the joining of the ___ and the ___.

A

Supraorbital v.

Angular v.

78
Q

____ veins from the vascular layer of the eyeball drain into the inferior ophthalmic v.

Block 5 Material (17 decks)

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