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OCULAR PHYSIOLOGY > THE ORBIT > Flashcards

THE ORBIT Flashcards

1
Q

What supports and provide protection to the orbital soft tissues?

A

The Bony Orbit

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2
Q

What makes up the bony orbit?

A

The roof, lateral wall, floor and medial wall

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3
Q

What bones make up the 4 walls

A

Sphenoid, Frontal, Ethmoid, Maxillary, Zygomatic, Palatine, Lacrimal

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4
Q

Which bones are common to both orbits

A

Sphenoid, Frontal, Ethmoid

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5
Q

What is the strongest portion of the orbital rim

A

zygomatic bone and zygomatic process of the frontal bone

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6
Q

What is the downside to having a concavity?

A

makes the eye prone to injury

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7
Q

what is the pros to having concavity

A

increases lateral visual field

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8
Q

What is the purpose of the orbital rim

A

protection from trauma

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9
Q

The orbital roof has a _____ shape?

A

triangular

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10
Q

What bones make up the orbital roof

A

Frontal, lesser wing of the sphenoid bone (posterior to frontal bone)

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11
Q

The lacrimal fossa holds what?

A

the lacrimal gland

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12
Q

T/F the lacrimal gland can’t be seen in the shallow orbit

A

False; don’t misdiagnose as a tumor

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13
Q

T/F The orbital rim is thin and mainly consists of the orbital plate of the maxillary bone

A

false; orbital floor. the orbital rim is thick and rounded at its anterior aperture

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14
Q

T/F The orbital floor is the strongest orbital wall

A

false; weakest

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15
Q

Orbital floor gives support to the eye and the ________ tissues and separates them from the ______sinus

A

adnexal; maxillary

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16
Q

T/F The floor extends to the apex

A

false

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17
Q 
Orbital floor is \_\_\_\_\_\_ to \_\_\_\_\_ mm long 
a) 35-50
b)15-40
C)20-40
D)35-40
A

35;40

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18
Q

T/F the floor easily deform to blunt trauma

A

T

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19
Q

______ bone and lack of support _____ the rate of fractures

A

thin; increases

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20
Q

Where does the floor blow out into in a blowout fracture

A

maxillary sinus

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21
Q

Why does the floor blow into the maxillary sinus

A

it provides protection to the eye and tissues

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22
Q

Patient has a BOF with loss of vision why?

A

Retinal detachment, retinal tear and/or optic nerve damage

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23
Q

Patient has a BOF with diplopia why?

A

Because of muscle entrapment

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24
Q

Patient has a BOF with enophthalmos why?

A

loss of support

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25
Q

Patient has a BOF with numb cheek why?

A

for damaged to the infraorbital nerve

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26
Q

What is enophthalmos?

A

sunken eye

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27
Q

When will a BOF be repaired with surgery

A

restricted strabismus, enophthalmos

28
Q

When would you cause a BOF

A

Thyroid eye disease

29
Q

The lateral orbital wall is form by ______ and ______ bones and _______ in shape

A

zygomatic malar; greater wing of sphenoid bone; triangular

30
Q

The medial orbital wall is _____ and _______

A

smallest; thin

31
Q

A ______ _______ of the ethmoid bone is extremely thin

A

Lamina papyracea

32
Q

What protects the medial wall from being fractured

A

the honeycomb structure of the ethmoid sinus bony lamina

33
Q

Which wall is fractured most often

A

Orbital floor

34
Q 
The globe reaches \_\_\_\_\_ of its adult size when an infant is \_\_\_\_\_ of age 
a) 90% 10months
b)90% 20 months
C)80% 10 months
D)80% 20 months
A

90%; 20 months

35
Q 
At birth the \_\_\_\_\_\_ diameter of the globe is \_\_\_\_\_ mm.  In adulthood it is \_\_\_\_ mm 
a) 16 , 24
b)10,  24
C)16, 20 
D)16, 10
A

anteroposterior;

A)16; 24

36
Q

What are the three factors that affect the size of globe?

A

refractive error (myopia), gender (males > females), ethnicity (Chinese smallest)

37
Q 
The volume of the globe is \_\_\_\_\_cm^3
a) 7
b)10
C)9
D)8
A

7

38
Q 
The volume of the orbit is \_\_\_\_\_cm^3
a) 60
b)40
C)30
D)10
A

30

39
Q 
The vertical diameter of the globe is  \_\_\_\_\_ and the horizontal diameter is \_\_\_\_\_
a) 23mm, 24 mm
b)23mm, 25 mm
C)23mm, 26 mm
D)23mm, 23.5 mm
A

23 mm; 23.5 mm

40
Q

What is exophthalmos

A

forward displacement of the globe

41
Q

Why can you not use proptosis to describe exophthalmos

A

both are a forward displacement but proptosis is of any object and is not specific to the eyeball

42
Q

Why does any displacement of the eye cause the globe to move forward?

A

the only place the orbit can acutely(suddenly)expand is anteriorly

43
Q

As you age what decreases and what does it cause

A

fat content and it causes enophthalamos

44
Q

What is the most common cause of unilateral and bilateral exophthalamus in adults

A

Thyroid eye disease

45
Q

T/F Can thyroid eye disease be only unilateral

A

F; it is unilateral or bilateral

46
Q

What accumulates in the EOM’s and/or connective tissue and fat and leads to swelling in thyroid eye disease

A

Glycosaminoglycans (GAG)

47
Q

What is craniofacial dysostosis and what can it cause

A

Defect in the normal ossification of fetal cartilages; exophthalmos

48
Q

What is a hemangioma and what can it cause

A

an abnormal buildup of blood vessels ; exophthalmos

49
Q

What is craniostenosis and what can it cause

A

fault (premature) in fusing of bones; exophthalmos

50
Q

What is buphthalmos and what can it cause

A

eye is stretched for some reason, all structures become longer; exophthalmos

51
Q

T/F severe hyperopia and buphthalmos may stimulate exophthalmos

A

False, severe myopia and buphthalmos may stimulate exophthalmos

52
Q

______ may lead to _____ exophthalmos of the contralateral eye

A

enophthalmos; pseudo

53
Q

What faults or defect in bones can cause exophthalmos

A

craniostenosis, craniofacial dysostosis

54
Q

What type of tumors can cause exophthalmos

A

inflammatory pseudotumors, benign and malignant tumors

55
Q

What abnormal blood vessel buildup can cause exophthalmos

A

hemangioma

56
Q

The amount of protrusion of the normal eye can be important _______ ________

A

clinical marker

57
Q

Where is the protrusion typically measured from

A

deepest part of the lateral orbital rim to the corneal apex

58
Q

What is the most accurate device in measuring protrusion

A

hertel exophthalmometer

59
Q

T/F a simple ruler cannot be used to measure protrusion

A

F; it can be used

60
Q

What three types of collagen make up the orbital connective tissue and describe them

A

CT I - structural integrity
CT III - adhesion between connective tissue and adipocytes
CT IV - basement membranes of connective tissue vessels

61
Q

What type of cells make up the orbital tissue

A

Fibroblasts and endothelial cells

62
Q

_____ percent of individuals have the _______ artery as the primary blood supply to the orbit. ______ percent of individuals have the _____ artery contribute equally through an accessory to ______ artery

A

96; Ophthalmic artery; 3; middle meningeal artery; ophthalmic

63
Q

T/F Orbital veins and arteries follow the same course in the system

A

F; the follow different course

64
Q

Orbital veins _____ parallel orbital arteries

A

do not; except lacrimal and ethmoidal veins

65
Q

T/F Orbital veins do not posses valves

A

T; valves prevent backflow

OCULAR PHYSIOLOGY (13 decks)

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