THE ORBIT

Question 1

Name the seven bones of the boney orbit?

Answer 1

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

Question 2

what bones are common to both orbits?

Answer 2

sphenoid, frontal, and ethmoid

Question 3

the orbital rim is the strongest where?

Answer 3

on the sides, laterally (zygomatic bone, and zygomatic processes of the frontal bone).

Question 4

The lateral rim is displaced, allowing for 100 degree depth view but making eye vulnerable. true or false

Answer 4

true

Question 5

the orbit gets its widest diameter how many cm behind the orbital rim?

Answer 5

1cm

Question 6

The orbital roof is what shape? Name the bones that make it up.

Answer 6

Triangular.
frontal bone
lesser wing of sphenoid
lacrimal fossa

Question 7

The orbital floor is the strongest wall of the eye and extends to the apex. True or False.

Answer 7

False. It is the weakest and doesn’t extend to the apex. it stops abruptly. Is 35-40mm long.

Question 8

what bone makes up orbital floor?

Answer 8

maxillary bone. very thin

Question 9

what does orbital floor do?

Answer 9

support the eye and adnexal connective tissues. separate it from maxillary sinus.

Question 10

Describe a Blow Out Fracture and the Symptoms.

Answer 10

blunt trauma to the orbital floor and damage to maxillary bone into maxillary sinus. 
symptoms:
diplopia 
numb cheek
loss of vision
enophthalmos

Question 11

what is enophthalmus?

Answer 11

displacement of eye in to orbit.

Question 12

what shape is the lateral wall and what bones make it up?

Answer 12

triangular.
zygomatic (anteriorly)
greater wing sphenoid (posteriorly)

Question 13

What bone makes up medial wall? Describe its significance.

Answer 13

Lamina Papyrcea of the Ethmoid bone. Very thin. located behind lacrimal crest. However, uniformly protected by honeycomb shaped ethmoid sinus bony lamina. smallest bone of eye.

Question 14

which gets fracture more often….lamina papyrcea or orbital floor?

Answer 14

orbital floor

Question 15

what is the anteroposterior diameter of the globe as infant and adult?

Answer 15

infant= 16mm
adult= 24mm
baby reaches 90% of adult size eye by 20 months.

Question 16

what are the volume measurements and anteroposterior and verticle and horizontal diameters of eye?

Answer 16

the volume of the globe is 7 cm3
the volume of the orbit is 30 cm3.
the anteroposterior 
	diameter is ≈24 mm
the vertical 
	diameter is ≈23 mm
the horizontal 
diameter is ≈23.5 mm

eye not perfect sphere.

Question 17

define exophthalmos

Answer 17

forward displacement of the eye.

Question 18

define proptosis

Answer 18

forward movement of any object, not specific to eye.

Question 19

what disease is the most common cause of exophthalmos?

Answer 19

Thyroid eye disease. This is when glycosaminoglycans accumulate in the extraocular muscles, connective tissues, and fat around the eye. Lead to swelling.

Question 20

what are other causes of exophthalmos?

Answer 20

hemangiomas, benign or malignant tumors, severe myopia and buphthalmos (elongated globe) inflammatory pseudotumors, and craniostenoses and the craniofacial dysostosis

Question 21

what is a Hertel exophthalometer used for?

Answer 21

Eye protrusion. You measure from lateral orbital rim to corneal apex.

Question 22

what does orbital connective tissue consist of?

Answer 22

fibroblasts, collagen 1, 3 and 4 and endothelial cells.

Question 23

what is collagen type 1, 3 and 4 function?

Answer 23

collagen 1:
structural integrity
collagen 3:
adhesive between connective tissue and adipocytes cells
collagen 4:
basement membranes of connective tissue to vessels.

Question 24

The orbital vasculature comes from where?

Answer 24

ophthalmic artery.

Question 25

Do the arterial and venous blood supply in eye run parallel to one another?

Answer 25

No. they travel two different routes.

except for lacrimal and ethmoidal veins.

Question 26

orbital veins possess valves. True or False.

Answer 26

False. they have no valves.