Question:easy
The length of the external auditory meatus is?
The length of the external auditory meatus is?
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Add the cartilaginous outer third (about 8 mm) to the bony inner two-thirds (about 16 mm).
Updated On: Jun 24, 2026
- 12 mm
- 16 mm
- 20 mm
- 24 mm
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: The external acoustic meatus runs an S-shaped course from the auricle to the eardrum and measures about 24 mm in the adult.
Step 2: Its length is the sum of two segments: the lateral cartilaginous portion of roughly 8 mm and the medial bony portion of roughly 16 mm.
Step 3: The cartilaginous part bears hair and ceruminous and sebaceous glands, so furuncles form only there, while the thin-skinned bony part contains the isthmus, the narrowest zone about 5 mm from the tympanic membrane where foreign bodies lodge.
Step 4: Combining 8 mm plus 16 mm confirms a total close to 24 mm, ruling out the 12, 16, and 20 mm options.
\[\boxed{\text{24 mm}}\]
Step 2: Its length is the sum of two segments: the lateral cartilaginous portion of roughly 8 mm and the medial bony portion of roughly 16 mm.
Step 3: The cartilaginous part bears hair and ceruminous and sebaceous glands, so furuncles form only there, while the thin-skinned bony part contains the isthmus, the narrowest zone about 5 mm from the tympanic membrane where foreign bodies lodge.
Step 4: Combining 8 mm plus 16 mm confirms a total close to 24 mm, ruling out the 12, 16, and 20 mm options.
\[\boxed{\text{24 mm}}\]
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