Sinuses may have originally developed to increase the available surface area for the sense of smell. Therefore, in humans, with olfaction limited to a much smaller area, sinuses may be vestigial anachronisms. Though their function is obscure, their medical significance is not. Sinuses frequently become infected due to obstruction of normal drainage, and negative pressure in a sinus can cause headache. Neoplasms which arise in the sinuses can be occult for quite a long time, so that they are usually very advanced at the time of diagnosis.
Posterior wall is adjacent to anterior cranial fossa.
Usually asymmetrical, occasionally absent. B. Maxillary - Paired, in maxilla. Superior wall - floor of orbit. Medial wall - lateral wall of nose. Inferiorly related to tooth-bearing area of maxilla.