Paranasal sinuses present at bih
High-Yield Explanation
The sinuses are rudimentary or even absent at bih.They enlarge rapidly during the age of 6 to 7 years i.e, at thevtime of eruption of permanent teeth and then after pubey.From bih to adult life, the growth of the sinuses is due to the enlargement of the bones; in old age, it is due to resorption of the surrounding cancellous bone. Ethmoid and maxillary sinuses present at bih Ref BDC volume;3.Sixth edition