Chapter 3: The Orbital Cavity Flashcards
How many individual bones form the orbit? Name them.
7
- maxilla, palantine, zygomatic, sphenoid, frontal, ethmoid, lacrimal
What forms the supraorbital margin?
Frontal bone.
What forms the infraorbital margin?
Laterally by the zygomatic bone.
Medially by the maxilla.
What forms the lateral margin?
Frontal process of the zygomatic bone below.
Zygomatic process of the frontal bone above.
What is the strongest part of the orbital margin?
Lateral margin.
What forms the medial margin?
Above by the maxillary process of the frontal bone.
Below by the lacrimal crest of the frontal process of the maxilla.
The concave roof (superior wall) is formed by what?
The orbital plate of the frontal bone (and to a small extent by the lesser wing of the sphenoid posteriorly).
What is the orbital roof invaded by anteromedially?
The frontal air sinus.
What is the anterolateral depression in the roof of the orbital cavity?
The lacrimal fossa (houses the orbital part of the lacrimal gland).
Describe the location of the spine for the pulley of the superior oblique muscle.
Medial to the supraorbital notch.
4mm behind the orbital margin.
What does the roof separate the orbital cavity from?
Anterior cranial fossa and frontal lobe.
What forms the thin inferior wall of the orbital cavity? (3)
(1) The orbital plate of the maxilla
(2) Orbital surface of the zygomatic arch
(3) Small orbital process of the palatine bone.
What does the orbital plate of the maxilla separate the orbital cavity from?
The maxillary sinus.
What separates the floor from the lateral wall posteriorly (it is connected anteriorly)?
The inferior orbital fissure.
The inferior orbital fissure is continuous with which groove?
The infraorbital groove.
At about the midpoint of the orbital floor, the infraorbital groove becomes the ……?
The infraorbital canal.
What does the infraorbital canal open onto the face as?
The infraorbital foramen.
Which wall is the thickest?
Lateral
What forms the lateral wall?
Anterior 1/3: Zygomatic bone
Posterior 2/3: Greater wing of the sphenoid bone.
What does the zygomatic bone separate the orbit from?
The temporal fossa.
What does the greater wing of the sphenoid bone separate the orbit from?
The temporal lobe in the middle cranial fossa.
The lateral wall and roof are separated posteriorly by the….? (they are continuous anteriorly)
Superior orbital fissure.
What does the superior orbital fissure communicate directly with?
The middle cranial fossa.
What is the name of the small prominence on the frontal process of the zygoma (just posterior to the orbital margin)?
Marginal tubercle.
What attaches to the marginal tubercle?
(1) The aponeurosis of the levator palpebrae superioris
(2) The lateral palpebral ligament
(3) Lateral cheek ligament
How many bones form the medial wall of the orbit? Name them, anterior -> posterior.
4
- The frontal process of the maxilla
- The lacrimal bone
- The orbital plate of the ethmoid
- Small part of the body of the sphenoid
What forms the largest part of the medial orbital wall?
The orbital plate of the ethmoid.
What does the orbital plate of the ethmoid separate the orbital cavity from?
The ethmoid sinuses
Is the orbital plate of the ethmoid a thick or thin bone?
Very thin.
Where is the lacrimal groove located?
On the anterior part of the medial wall.
What does the lacrimal groove hold?
The lacrimal sac.
The optic canal lies in which bone?
In the lesser wing of the sphenoid.
What is related medially to the optic canal?
The body of sphenoid.
OPENINGS INTO THE ORBIT
Name the nerve and vessel that travel through the optic canal.
Optic nerve (CN II) Ophthalmic artery.
OPENINGS INTO THE ORBIT
Name the nerves and vessel that travel through the superior orbital fissure.
- Oculomotor n. (III)
- Trochlear n. (IV)
- Abducent n. (VI)
- Trigeminal n. ophthalmic division CN V1 (lacriminal n, frontal n. , nasociliary n.)
- Superior ophthalmic vein.
OPENINGS INTO THE ORBIT
Name the nerves and vessels that travel through the inferior orbital fissure.
- Infraorbital n. (CNV2)
- Zygomatic n. (CNV2)
- Infraorbital a. and v.
- Inferior ophthalmic vein
OPENINGS INTO THE ORBIT
Infraorbital canal.
- Infraorbital n. , a., and v,
OPENINGS INTO THE ORBIT
Supraorbital foramen.
Supraorbital n. (lateral branch)
Supraorbital a.
OPENINGS INTO THE ORBIT
Frontal incisure.
Supraorbital n. (medial branch)
Supratrochlear artery.
OPENINGS INTO THE ORBIT
Anterior ethmoidal foramen.
Anterior ethmoidal n. a. v.
OPENINGS INTO THE ORBIT
Posterior ethmoidal foramen.
Posterior ethmoidal n. a. v.
OPENINGS INTO THE ORBIT
Nasolacriminal canal.
Nasolacriminal duct.
