ORBITAL ANATOMY MCQs

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In this blog post we shall discuss 10 important mcqs related to the bony anatomy of the orbit. A detailed conceptual video on the anatomy of bony orbit with illustrations is available on our YouTube channel " Insight Ophthalmology ".

Link :- 

Now let us go through the most important and most asked questions in orbit anatomy. 

Question 1 

Regarding walls of the orbit, which statement is MOST likely to be true?

1. The roof comprises the orbital plate of frontal bone and body of sphenoid.
2. The floor comprises the orbital plate of maxilla, orbital surface of zygomatic, and orbital process of palatine.
3. The lateral wall comprises the zygomatic bone and lesser wing of sphenoid.
4. The medial wall comprises the frontal process of maxilla, lacrimal bone, orbital plate of ethmoid, and greater wing of sphenoid.

Question 2 

Orbit is made up of many bones ?

1. Six 
2. Seven 
3. Eight 
4. Nine 

Question 3

Which of the following is the thinnest part of the orbit?

1. Medial wall
2. Lateral wall
3. Floor of the orbit
4. Roof of the orbit

Question 4

Most common site for the blow out fracture is?

1. posteromedial aspect of the floor
2. antero medial aspect of floor
3. medial wall
4. roof 

Question 5

Identify the condition in the radioimage shown below. Presence of what structures is responsible for development of this condition?

1. orbital abscess,
2. subperiosteal abscess
3. orbital cellutitis
4. preseptal cellulitis 

Question 6

Orbital roof is formed by which of the following bones?

1. frontal bone +greater wing of sphenoid
2. lesser wing of sphenoid
3. maxillary bone and palatine bone
4. lesser wing of sphenoid and the frontal bone

Question 7

Identify the bone labelled and mention which wall of the orbit it forms ? 

1. Lesser wing of sphenoid, roof
2. Greater wing of sphenoid, lateral wall of orbit 
3. Zygomatic bone, lateral wall
4. Palatine bone, floor 

Question 8

Whitnall tubercle is located in which wall of the orbit?

1. Superior nasal aspect of roof 
2. Medial wall
3. Lateral wall
4. Floor 

Question 9

Which of the following structures do not attach to the lateral orbital wall tubercle( whitnall tubercle)?

1. Lateral check ligament
2. Suspensory ligament / Lockwood ligament
3. Lateral horn of the LPS
4. Whitnall ligament 

Question 10

Volume of the eyeball and of orbit is ?

1. 30cc, 7 cc
2. 7cc, 30cc 
3. 45cc, 6 cc
4. 30 cc, 3 cc 

ANSWERS: 

Question 1 : 2 

Question 2 : 2 

question 3 : 1

Question 4 : 1 

Question 5 : 2 , ethmoidal foramen in medial wall

Question 6 : 4 

Question 7 : 2

Question 8 :2

Question 9 : 4 

Question 10 : 2

There are seven bones of the orbit: Maxilla, Frontal, Zygomatic,

Ethmoid, Lacrimal, Sphenoid, and Palatine.

You can remember these with the following mnemonic: ‘Many Friendly Zebras Enjoy Lazy Summer Picnics’. 

The thinnest walls of the orbit are the ethmoid bone, also known as the lamina papyracea, between the orbit and the ethmoid sinuses along the medial wall, and the maxillary bone, particularly in its posteromedial portion.

Although the lamina payracea is the thinnest wall, it is supported by the ethmoidal sinus septa and therefore not as prone to fracture as the orbital floor which is unsupported .

LANDMARKS ON LATERAL WALL :-

•The lateral orbital tubercle of Whitnall, with multiple attachments

•the Whitnall ligament, which inserts onto the lateral orbital wall several millimeters (mm) above the lateral orbital tubercle via attachments to the lacrimal gland fascia

•The frontozygomatic suture, located 1 cm above the tubercle

ATTACHMENTS OF WHITNALL LIGAMENT

1. •Lateral canthal tendon
2. •Lateral horn of the levator aponeurosis
3. •The check ligament of the lateral rectus
4. •The Lockwood ligament (the suspensory ligament of the globe)