Which statement about the orbital floor is NOT true?

• A. The floor contains the ethmoid bone.
• B. The floor is formed by the maxillary, palatine, and zygomatic bones.
• C. The orbital floor is the weakest part of the orbit.
• D. The orbital floor contributes to the bottom boundary of the orbit.

Answer: (A)

The orbital floor is formed mostly by the maxilla, with contributions from the palatine and zygomatic bones; the ethmoid bone does not contribute to the floor. The ethmoid forms the medial wall of the orbit (the lamina papyracea), not the floor. So saying the floor contains the ethmoid bone is not true. The floor does form the bottom boundary of the orbit and is considered the weakest part of the orbital walls, which helps explain why it’s a common site for blowout fractures. The other statements align with this anatomy: the floor’s bony contributors, its position as the bottom boundary, and its relative weakness.