Orbit Volume 1

Question 1

What is the average distance between the two medial walls of the orbit?

Answer 1

25 mm

Question 2

Where is the location of the widest portion of the orbit?

Answer 2

1 mm behind the orbital rim

Question 3

What is the volume of the average adult orbit?

Answer 3

30 cc

Question 4

What are the average dimensions of the adult orbit?

Answer 4

35 x 40 x 45 mm

Question 5

What is the average distance from the posterior globe to the optic foramen?

Answer 5

18 mm

Question 6

Name the 7 bones of the orbit.

Answer 6

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

Question 7

Where is the trochlea fossa located?

Answer 7

5 mm behind the superior nasal orbital rim

Question 8

What structures are located within the supraorbital notch?

Answer 8

Supraorbital blood vessels and supraorbital nerve

Question 9

What bones make up the roof of the orbit?

Answer 9

Frontal bone and lesser wing of the sphenoid

Question 10

What bones make up the lateral walls of the orbit?

Answer 10

Zygomatic bone and greater wing of the sphenoid

Question 11

What is the thickest and strongest orbital wall?

Answer 11

Lateral wall

Question 12

What bones make of the medial orbit?

Answer 12

Ethmoid,lacrimal, maxillary, and sphenoid bones

Question 13

Name the two thinnest walls of the orbit.

Answer 13

Lamina papyracae and maxillary bone

Question 14

What is a common source of spread of infection in children with orbital cellulitis and proptosis?

Answer 14

Transmission from the ethmoid sinuses through the lamina papyracae

Question 15

What bones make up the floor of the orbit?

Answer 15

Maxillary, palantine, and zygomatic bones

Question 16

What is the shortest wall of the orbit?

Answer 16

Orbital floor

Question 17

Name the contents of the infraorbital groove.

Answer 17

Infraorbital artery and maxillary division of the trigeminal nerve

Question 18

What separates the greater and lesser wings of the sphenoid?

Answer 18

Superior orbital fissure

Question 19

Name the contents of the superior orbital fissure.

Answer 19

CN Ill, IV,and VI, First divisions of CN V, and branches of the orbital vein

Question 20

What nerve is commonly damaged in blowout fractures of the orbital floor?

Answer 20

Infraorbital nerve (branch of the maxillary nerve)

Question 21

What is the average length of the optic canal?

Answer 21

8 to 10 mm

Question 22

What is the average length of the intraorbital optic nerve?

Answer 22

30 mm

Question 23

What is the average diameter of the optic nerve?

Answer 23

4 mm

Question 24

What is the common origin of the 4 rectus muscles?

Answer 24

Annulus of Zinn

Question 25

What is the only cranial nerve that innervates an extraocular muscle but does not pass through muscle cone when entering the omit?

Answer 25

CN IV

Question 26

Name the three major branches of the ophthalmic artery.

Answer 26

1. Extraocular muscular branches 2.Central retinal artery 3.Posterior ciliary arteries

Question 27

What vessel provides the main venous drainage of the orbit?

Answer 27

Superior ophthalmic vein

Question 28

Name the 3 main brandies of the ophthalmic division of the maxillary nerve.

Answer 28

1. Frontal nerve 2. Lacrimal nerve 3. Nasociliary nerve

Question 29

What nerve innervates the medial canthus?

Answer 29

Supratrochlear nerve

Question 30

What nerves innervates the upper eyelid?

Answer 30

Lacrimal and supratrochlear nerve

Question 31

What nerve innervates the forehead?

Answer 31

Supraorbital nerve

Question 32

What nerve innervates the iris, cornea, and ciliary muscle?

Answer 32

Long ciliary nerve

Question 33

In what bone can the optic canal be found?

Answer 33

Lesser wing of the sphenoid

Question 34

What region of the nasal cavity does the nasolacrimal duct open into.?

Answer 34

Interior meatus

Question 35

What structure is found in the inferior orbital fissure?

Answer 35

Maxillary nerve