Orbit Volume 3

Question 1

What is the anatomical significance of the eyelid crease?

Answer 1

Denotes the site of levator aponeurosis attachment to the pretarsal obicularis oculi and skin

Question 2

How does the eyelid crease typically differ in Asian patients?

Answer 2

Eyelid crease is typically lower in Asian patients

Question 3

What muscle is the primary protractor of the eyelid?

Answer 3

Orbicularis oculi

Question 4

Name the 3 parts of the orbicularis oculi muscle.

Answer 4

1. Pretarsal 2.Preseptal 3.Orbital

Question 5

What portions of the orbicularis oculi are integral to involuntary closure of the eyelid (e.g. blink)?

Answer 5

Preseptal and pretarsal

Question 6

What muscle makes up the lateral canthal tendon?

Answer 6

Pretarsal orbicularis oculi

Question 7

What muscle makes up the gray line of the eyelid?

Answer 7

Muscle of Riolan (lies posterior to orbicularis oculi)

Question 8

Where does the orbital septum fuse with the levator aponeurosis in the upper eyelid?

Answer 8

2 to 5 mm above the superior tarsal border

Question 9

What important landmark in eyelid surgery and laceration repair in determining location of orbital septum and levator aponeurosis?

Answer 9

Central orbital fat pad

Question 10

What are the retractors of the upper eyelid?

Answer 10

Levator muscle (aponeurosis) and Muller’s muscle

Question 11

What are the retractors of the lower eyelid?

Answer 11

Capsulopalebral fascia and inferior tarsal muscle

Question 12

What is the average length of the muscular portion of the levator muscle?

Answer 12

40 mm

Question 13

What is the average length of the levator aponeurosis?

Answer 13

14 to 20 mm

Question 14

What structure divides the lacrimal gland into the orbital and palpebral lobes?

Answer 14

Lateral horn of the levator aponeurosis

Question 15

Where does the posterior levator aponeurosis attach to the anterior surface of the tarsus?

Answer 15

Approx.3 mm above the eyelid margin

Question 16

What is the average height of the upper eyelid tarsus?

Answer 16

10 to 12 mm

Question 17

What is the average height of the lower eyelid tarsus?

Answer 17

4 mm

Question 18

What is the average thickness of the tarsus?

Answer 18

1 mm

Question 19

What nerve innervates the levator muscle?

Answer 19

Superior division of CN Ill (also supplies superior rectus muscle)

Question 20

What substance do Goblet cells produce?

Answer 20

Mucin (makes up posterior layer of the tear film)

Question 21

Where are the meibomian gland orifices of the eyelid located?

Answer 21

Just posterior to the gray line

Question 22

What is the approximate number of eyelashes in the upper eyelid?

Answer 22

100

Question 23

What is the approximate number of eyelashes in the lower eyelid?

Answer 23

50

Question 24

What is the approximate number of the meibomian glands in the upper eyelid?

Answer 24

25

Question 25

What is the approximate number of meibomian glands in the lower eyelid?

Answer 25

20

Question 26

What is the venous drainage of the pretarsal eyelid?

Answer 26

Angular vein medially and superficial temporal vein laterally

Question 27

What is the venous drainage of the posttarsal eyelid?

Answer 27

Orbital veins and facial vein (along with pterygoid plexus)

Question 28

What glands are located within the tarsus?

Answer 28

The meibomian glands

Question 29

What is the function of the meibomian glands?

Answer 29

Holocrine, oil-producing sebaceous glands