ABSTRACT
PARANASAL SINUSES: EMBRYOLOGY AND DEVELOPMENT Maxillary Sinuses The paranasal sinuses develop as outgrowths of the walls of the primitive (fetal) nasal cavities (1,2). Maxillary and ethmoid sinuses develop during fetal life. Frontal and sphenoid sinuses are not present at birth, but develop during the early years of life (2,3). By 4-5 months after birth, the maxillary sinus can be readily identified particularly on computed tomography (CT) scans. After birth, growth of the maxillary sinus continues rapidly until about 3 years of age, and then slowly progress until the seventh year (3). At this time another acceleration in growth occurs until the age of 12 years. After the twelfth year much of the growth is related to an invasion of the alveolar process following the eruption of the secondary dentition (3).
