Which is not a pa of paranasal sinus?: (A) frontal, (B) Ethmoid, (C) Sphenoid, (D) Pyriform
Answer is D. Paranasal sinuses are air containing cavities in ceain bones of skull. They are four on each side. Clinically,paranasal sinuses have bern divided into Anterior-Maxillary,Frontal, Anterior ethmoidal. posterir-Posterior ethmoid,sphenoid sinus. Ref Dhingra 6/e,p 187.