Sinusitis occurs as a result of obstruction of the osteomeatal unit, which is located in the vicinity of the maxillary sinus ostium (Fig. 1). Because of obstruction, mucus accumulates inside the ...

The four paranasal sinuses (maxillary, frontal, ethmoid and sphenoid) develop as outpouchings of the nasal mucosa. They remain connected to the nasal cavity via narrow ostia with a lumen diameter ...