Chapter 3: The Orbital Cavity

Question 1

How many individual bones form the orbit? Name them.

Answer 1

7

- maxilla, palantine, zygomatic, sphenoid, frontal, ethmoid, lacrimal

Question 2

What forms the supraorbital margin?

Answer 2

Frontal bone.

Question 3

What forms the infraorbital margin?

Answer 3

Laterally by the zygomatic bone.

Medially by the maxilla.

Question 4

What forms the lateral margin?

Answer 4

Frontal process of the zygomatic bone below.

Zygomatic process of the frontal bone above.

Question 5

What is the strongest part of the orbital margin?

Answer 5

Lateral margin.

Question 6

What forms the medial margin?

Answer 6

Above by the maxillary process of the frontal bone.

Below by the lacrimal crest of the frontal process of the maxilla.

Question 7

The concave roof (superior wall) is formed by what?

Answer 7

The orbital plate of the frontal bone (and to a small extent by the lesser wing of the sphenoid posteriorly).

Question 8

What is the orbital roof invaded by anteromedially?

Answer 8

The frontal air sinus.

Question 9

What is the anterolateral depression in the roof of the orbital cavity?

Answer 9

The lacrimal fossa (houses the orbital part of the lacrimal gland).

Question 10

Describe the location of the spine for the pulley of the superior oblique muscle.

Answer 10

Medial to the supraorbital notch.

4mm behind the orbital margin.

Question 11

What does the roof separate the orbital cavity from?

Answer 11

Anterior cranial fossa and frontal lobe.

Question 12

What forms the thin inferior wall of the orbital cavity? (3)

Answer 12

(1) The orbital plate of the maxilla
(2) Orbital surface of the zygomatic arch
(3) Small orbital process of the palatine bone.

Question 13

What does the orbital plate of the maxilla separate the orbital cavity from?

Answer 13

The maxillary sinus.

Question 14

What separates the floor from the lateral wall posteriorly (it is connected anteriorly)?

Answer 14

The inferior orbital fissure.

Question 15

The inferior orbital fissure is continuous with which groove?

Answer 15

The infraorbital groove.

Question 16

At about the midpoint of the orbital floor, the infraorbital groove becomes the ……?

Answer 16

The infraorbital canal.

Question 17

What does the infraorbital canal open onto the face as?

Answer 17

The infraorbital foramen.

Question 18

Which wall is the thickest?

Answer 18

Lateral

Question 19

What forms the lateral wall?

Answer 19

Anterior 1/3: Zygomatic bone

Posterior 2/3: Greater wing of the sphenoid bone.

Question 20

What does the zygomatic bone separate the orbit from?

Answer 20

The temporal fossa.

Question 21

What does the greater wing of the sphenoid bone separate the orbit from?

Answer 21

The temporal lobe in the middle cranial fossa.

Question 22

The lateral wall and roof are separated posteriorly by the….? (they are continuous anteriorly)

Answer 22

Superior orbital fissure.

Question 23

What does the superior orbital fissure communicate directly with?

Answer 23

The middle cranial fossa.

Question 24

What is the name of the small prominence on the frontal process of the zygoma (just posterior to the orbital margin)?

Answer 24

Marginal tubercle.

Question 25

What attaches to the marginal tubercle?

Answer 25

(1) The aponeurosis of the levator palpebrae superioris (2) The lateral palpebral ligament (3) Lateral cheek ligament

Question 26

How many bones form the medial wall of the orbit? Name them, anterior -> posterior.

Answer 26

4 - The frontal process of the maxilla - The lacrimal bone - The orbital plate of the ethmoid - Small part of the body of the sphenoid

Question 27

What forms the largest part of the medial orbital wall?

Answer 27

The orbital plate of the ethmoid.

Question 28

What does the orbital plate of the ethmoid separate the orbital cavity from?

Answer 28

The ethmoid sinuses

Question 29

Is the orbital plate of the ethmoid a thick or thin bone?

Answer 29

Very thin.

Question 30

Where is the lacrimal groove located?

Answer 30

On the anterior part of the medial wall.

Question 31

What does the lacrimal groove hold?

Answer 31

The lacrimal sac.

Question 32

The optic canal lies in which bone?

Answer 32

In the lesser wing of the sphenoid.

Question 33

What is related medially to the optic canal?

Answer 33

The body of sphenoid.

Question 34

OPENINGS INTO THE ORBIT | Name the nerve and vessel that travel through the optic canal.

Answer 34

``` Optic nerve (CN II) Ophthalmic artery. ```

Question 35

OPENINGS INTO THE ORBIT | Name the nerves and vessel that travel through the superior orbital fissure.

Answer 35

- Oculomotor n. (III) - Trochlear n. (IV) - Abducent n. (VI) - Trigeminal n. ophthalmic division CN V1 (lacriminal n, frontal n. , nasociliary n.) - Superior ophthalmic vein.

Question 36

OPENINGS INTO THE ORBIT | Name the nerves and vessels that travel through the inferior orbital fissure.

Answer 36

- Infraorbital n. (CNV2) - Zygomatic n. (CNV2) - Infraorbital a. and v. - Inferior ophthalmic vein

Question 37

OPENINGS INTO THE ORBIT | Infraorbital canal.

Answer 37

- Infraorbital n. , a., and v,

Question 38

OPENINGS INTO THE ORBIT | Supraorbital foramen.

Answer 38

Supraorbital n. (lateral branch) Supraorbital a.

Question 39

OPENINGS INTO THE ORBIT | Frontal incisure.

Answer 39

Supraorbital n. (medial branch) Supratrochlear artery.

Question 40

OPENINGS INTO THE ORBIT | Anterior ethmoidal foramen.

Answer 40

Anterior ethmoidal n. a. v.

Question 41

OPENINGS INTO THE ORBIT | Posterior ethmoidal foramen.

Answer 41

Posterior ethmoidal n. a. v.

Question 42

OPENINGS INTO THE ORBIT | Nasolacriminal canal.

Answer 42

Nasolacriminal duct.