Question:easy
Which of the following is not a part of the ethmoid bone?
Which of the following is not a part of the ethmoid bone?
Show Hint
Among the nasal conchae, only one is its own separate bone rather than an ethmoidal scroll.
Updated On: Jun 24, 2026
- Agger nasi
- Crista galli
- Uncinate process
- Inferior turbinate
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: Recall the components of the ethmoid bone. It is made of the cribriform plate, the perpendicular plate, and the two lateral ethmoidal labyrinths (masses of air cells). Several named landmarks belong to these parts.
Step 2: Check each option against this list. The crista galli is the upward midline crest on the cribriform plate. The uncinate process is a hook-like lamina of the labyrinth that helps bound the maxillary sinus opening. The agger nasi represents the most anterior ethmoidal air cells.
Step 3: Now consider the turbinates. The superior and middle conchae are scrolls that arise from the ethmoidal labyrinth, so they are ethmoidal. The inferior concha, however, develops and exists as an entirely separate facial bone of its own.
Step 4: Therefore the inferior turbinate is the odd one out, as it does not arise from the ethmoid bone at all.
\[\boxed{\text{Inferior turbinate}}\]
Step 2: Check each option against this list. The crista galli is the upward midline crest on the cribriform plate. The uncinate process is a hook-like lamina of the labyrinth that helps bound the maxillary sinus opening. The agger nasi represents the most anterior ethmoidal air cells.
Step 3: Now consider the turbinates. The superior and middle conchae are scrolls that arise from the ethmoidal labyrinth, so they are ethmoidal. The inferior concha, however, develops and exists as an entirely separate facial bone of its own.
Step 4: Therefore the inferior turbinate is the odd one out, as it does not arise from the ethmoid bone at all.
\[\boxed{\text{Inferior turbinate}}\]
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