Paranasal sinuses presents at bih are

Paranasal sinuses develop as outpouchings from the mucous membrane of a lateral wall of the nose. The growth of sinuses continues during childhood and into early adult life. Radiologically maxillary sinuses can be identified at 4-5 months, ethmoids at 1 year, sphenoid at 4 years and frontals at 6 years. Reference: Diseases of ear, nose and throat; PL Dhingra; 6th edition; Pg no.189