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Development

Maxillary sinus is the first paranasal sinuses to form. At birth, it is about 6 to 8 cm 3 in volume, elongated, as is orientated in antero-posterior direction, located at the next to the medial orbital wall of the eye. The lateral wall of the maxillary sinus goes beneath the medial orbital wall during the first year of life, extends laterally pass the infraorbital groove by the age of four years, and reach the maxilla by the age of nine years. After the first permanent tooth erupted at the age of six to seven, aeration of maxillary sinus is the main growth feature. At the final phase of aeration, the floor of maxillary sinus is four to five millimetres below the floor of nasal cavity. However, timing of maxillary sinus growth is variable in different people.