This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
Quadrilateral cailage is attached to all the following bony structures, EXCEPT: 
Select and explain. 
A. Ethmoid, B. Vomer, C. Sphenoid, D. Maxilla
C: Sphenoid
Answer: C: Sphenoid 
Explanation: Cailaginous pa of nasal septum is formed by a quadrilateral cailage. It is attached to the perpendicular plate of the ethmoid bone posterosuperiorly, to the anterior border of vomer posteriorly and to the internasal crest superiorly and to the nasal crest of the maxilla and anterior nasal spine inferiorly.