Orbit

Question 1

The orbit attains its widest diameter where?

Answer 1

1 cm behind the orbital rim

Question 2

The orbital roof is what shape?

Answer 2

Triangular shape

Question 3

Orbital Roof is formed by which bones?

Answer 3

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

Question 4

The strongest portion of the orbital rim?

Answer 4

Laterally

(zygomatic bone + zygomatic process of the frontal bone)

Question 5

Is the lateral rim a posteriorly or anteriorly directed concavity?

Answer 5

Posteriorly

Question 6

What is the function of the orbital rim?

Answer 6

protection from trauma

Question 7

The orbial rim is (thick or thin) and (rounded or flat) at its (posterior or anterior) aperture?

Answer 7

Thick

Rounded

Anterior

Question 8

Where is the lacrimal fossa found?

Answer 8

In the antero-lateral angle of the orbital roof

Question 9

Seven bones that make up the 4 walls of the orbit?

Answer 9

Sphenoid

Frontal

Ethmoid

Maxillary

Zygomatic

Palatine

Lacrimal

Question 10

Which bones make up both orbits?

Answer 10

Ethmoid

Sphenoid

Frontal

Question 11

What is the bony orbit designed to do?

Answer 11

Support and provide protection to the orbital soft tissues

Question 12

What do the soft tissues of the orbit consist of?

Answer 12

The globe and its supporting adnexa

Question 13

The bony orbit serves as the ______ of the globe

Answer 13

Socket

Question 14

The bony orbit is described of being made up of a ______, _____ wall, _______ , and _____ wall

Answer 14

Roof

Lateral

Floor

Medial

Question 15

Is the oribital floor thin or thick?

Answer 15

thin

Question 16

What bone(s) does the orbital floor mainly consist of?

Answer 16

The orbital plate of the maxillary bone

Question 17

What is the function of the orbital floor?

Answer 17

Support to the eye and adnexal tissues and separates them from the maxiallry sinus.

Question 18

Which part of the orbit is the weakest?

Answer 18

The orbital floor

Question 19

The floor does not extend to the _____ and is ____ to ____ mm long

Answer 19

apex

35 - 40

Question 20

The eyeball is about ____ inch(es)

Answer 20

1 inch

Question 21

Why is there an increase in the rate of fractures in the orbital floor?

Answer 21

Thin bone and lack of support

Question 22

The orbital floor easily ______ to blunt trauma

Answer 22

deforms

Question 23

The floor act like a ____ ____ and blows out into the _____ _____ providing protection to the eye and tissue

Answer 23

release valve

maxillary sinus

Question 24

What symptom does the patient experience with a blow-out fracture of the orbital floor?

Answer 24

Loss of vision

Diplopia

Enophthalmos

Numb Cheek (damage to infraorbital nerve)

Question 25

What bone(s) make up the lateral orbital wall? What shape do they make?

Answer 25

Zygomatic (malar) bone anteriorly Greater wing of the sphenoid bone posteriorly Triangular shape

Question 26

Which portion of the orbit is smallest?

Answer 26

Medial Orbital Wall

Question 27

Is the medial wall of the orbital thin or thick?

Answer 27

thin

Question 28

Which bone(s) makes up the meidal orbit wall?

Answer 28

Lamina papyracea of the ethmoid bone

Question 29

How is the ethmoid bone supported?

Answer 29

Uniformly supported by the honeycombed structure of the ethmoid sinus bony lamina

Question 30

Which wall is fractured more often? Medial Wall or Floor of the Orbit?

Question 31

At birth, the anteroposterior diameter of the globe is ______ mm

Answer 31

16 mm

Question 32

When does the globe reach 90% of its adult size?

Answer 32

At 20 months of age

Question 33

At adulthood the anteroposterior diameter of the globe is?

Answer 33

~24 mm (can vary 20-30 mm)

Question 34

What is the volume of the globe?

Answer 34

7 cm³

Question 35

What is the volume of the orbit?

Answer 35

30 cm³

Question 36

The anteroposterior diameter of the globe is?

Answer 36

~24 mm

Question 37

What is the vertical diameter of the globe?

Answer 37

~23 mm

Question 38

What is the horizontal diameter of the globe?

Answer 38

~23.5 mm

Question 39

What is proptosis?

Answer 39

The forward displacement of any object (not specific to the eyeball)

Question 40

What is exophthalmos?

Answer 40

The forward displacement of the globe

Question 41

Where is the only place the orbit can acutely expand?

Answer 41

anteriorly

Question 42

What is enophthalmos?

Answer 42

The retrodisplacement of the globe posterior into the orbit

Question 43

What is the most common cause of exophthalmos?

Answer 43

Thyroid eye disease

Question 44

What causes thyroid eye disease?

Answer 44

Caused by inflammatory reaction of an unknown cause Glycosaminoglycans accumulate in the extraocular muscles and/or connective tissue and fat and lead to swealling

Question 45

Other causes of exophthalmos?

Answer 45

Hemangiomas Inflammatory pseudotumors Benign and malignant tumors Craniostenoses and the craniofacial dysostis severe myopia and buphthalmos may simulate exophthalmos (elognated globe)

Question 46

Enophthalmos may lead to \_\_\_\_\_\_exophthalmos of the contralateral eye

Answer 46

pseudo

Question 47

How is protusion usually measured?

Answer 47

From the deepest part of the lateral orbital rim to the cornal apex

Question 48

What is the most accurate exophthalmometer?

Answer 48

The Hertel exophthalmometer

Question 49

Which artery provides the primary blood supply to the orbit?

Answer 49

opthalmic artery

Question 50

orbital veins (do or do not) parallel orbital arteries, except _____ and ____ veins

Answer 50

Do Not lacrimal and ethmodial veins

Question 51

Do orbital veins possess valves?

Answer 51

No