Question

A blow out fracture of the orbit most commonly involves the:

• A. Floor
• B. Medial wall
• C. Lateral wall
• D. Roof

Hint:

The thinnest orbital wall, hollowed by the infraorbital canal, is the floor.

Answer 1

The Correct Option is A

Step 1: A blowout fracture happens when a sudden rise in intra-orbital pressure (a blunt object such as a fist or ball striking the globe) is transmitted to the orbital walls, which give way at their weakest point.
Step 2: The orbital FLOOR is the weakest wall. The infraorbital neurovascular bundle runs through it, and the bone overlying that canal is paper-thin (roughly 0.2-0.4 mm), so this is where the fracture characteristically occurs.
Step 3: The lateral wall (zygomatic and greater wing of sphenoid) is the thickest and strongest, the roof is buttressed by the frontal bone, and although the very thin medial wall (lamina papyracea) can also fracture, the floor is the classic and most common "blowout" site.
Step 4: Clinically a floor blowout traps the inferior rectus, giving diplopia on upgaze, enophthalmos and infraorbital nerve numbness. Hence option a, Floor, is correct.