Lecture 5: Orbit

Question 1

Answer 1

1. Palantine bone
2. Ethmoid bone
3. Lacrimal bone
4. Maxilla
5. Zygomatic bone
6. Frontal bone
7. Sphenoid bone

Question 2

Answer 2

1.

Question 3

Answer 3

1. Opthalmic artery
2. Superior opthalmic vein

Question 4

Answer 4

Question 5

Label as many features as you can.

Answer 5

Question 6

Answer 6

1. Trochlea

2 & 11. Superior oblique

3 & 12. Sup. rectus

4. Medial rectus

5 & 9. Inferior rectus

6 & 8. Inferior oblique

7 & 10: Lateral rectus

13. Levator palpabrae superioris

Question 7

Answer 7

1. Superior orbital fissure
2. Lacrimal nerve
3. Sup. opthalmic vein
4. Frontal nerve
5. Trochlear nerve (CNIV)
6. Sup. rectus
7. lateral rectus
8. Inf. rectus
9. Medial rectus
10. Optic nerve
11. Opthalmic artery
12. N/A
13. Sup. division of CN3, Nasocillary nerve, Inf div of CN3, CN6 (Clockwise notation)
14. LPS
15. SO
16. Inf. opthalmic vein

Question 8

Answer 8

Question 9

Whats this nerve?

Answer 9

Trochlear (CN4)

Question 10

Whats this nerve? What branches does it give off?

Answer 10

Opthalmic nerve:

• Lacrimal nerve
• Frontal nerve
• Nasocilliary nerve

Question 11

What defines the apex of the orbit?

What defines the base?

Answer 11

Apex: Posteriormedial bit

Base: Anterior orbit

Question 12

What makes of the roof of the orbit?

Answer 12

• Orbit portion of frontal bone
• Small sphenoid portion

Question 13

What makes up the medial part of the orbit?

Answer 13

• Ethmoid
• Lesser wing of sphenoid
• Lacrimal
• Palantine (may be included in floor)
• Maxilla

Question 14

What does the lateral aspect of the orbit consist of?

Answer 14

• Zygomatic bone
• Greater wing of sphenoid

Question 15

What does the floor of the orbit consist of?

Answer 15

• Maxilla
• Zygotmatic
• Palantine

Question 16

Where do most fractures of the orbit occur?

Answer 16

In the floor as the resultant force tends to be downwards

Question 17

The subcutaneous space of the eye represents what?

Answer 17

A potential space. Therefore blood can enter and cause the swelling seen with black eyes.

Question 18

What nerve innervates the orbicularis oculi?

Answer 18

Facial n. CN7

Question 19

What are the layers of the eyelid?

Answer 19

1. Tarsus+levator palpebrae superioris and superior tarsal muscle
2. Orbital septum (periosteum)
3. Obicularis oculi muscle

Question 20

What does the tarsal gland secrete?

Answer 20

Oil, assits gentle closure of the eye (vs just water)

Question 21

What nerve(s) innervates the superior tarsal muscle and superioris muscle?

Answer 21

Superioris (CN3)

Superior tarsal (ANS specifically SNS)

Question 22

What does a partial ptosis of the upper eyelid represent?

Answer 22

SNS damage.

LPS is voluntary (CN3). SUperior tarsus muscle is under ANS control therefore partial ptosis suggests preservation of voluntary muscles

Question 23

Describe the blood supply of the eyelid:

Answer 23

Art: Branches of opthalmic, facial and superficial temporal artery.

Venous: Sup&Inf opthalmic vein branches, facial and angular veins (large network of veins likely)

Question 24

What creates the periosteal layer of the orbit? (refer to diagram if unsure)

Answer 24

Perioribta

Dura mater

Periosteum

Orbital septum

Question 25

What creates the lacrimal apparatus?

Answer 25

Lacrimal gland (tears)

Lacrimal canniculi

Lacrimal sac

Nasolacrimal duct

Question 26

What are the neurovascular structures of the orbit?

Answer 26

• Opthalmic artery + optic nerve (optic canal)
• Opthalmic vein (sup and inf branches)
• CN 2,3,4 (CN5 V1), 7