Paranasal sinuses are found in three bones of the neurocranium (braincase), the frontal bone, ethmoid bone, and sphenoid bone. The maxilla is the only facial bone (viscerocranium) that contains its own sinuses., What is frontal sinusitis and what causes it? Frontal sinusitis refers to inflammation of the sinuses located just above the eyes and on the forehead. A common cause of the condition is, Frontal sinuses: The right and left frontal sinuses are located in the center of the forehead (frontal bone) just above each eye. Maxillary sinuses: These are the largest of the, The maxillary sinuses are the largest of all the paranasal sinuses. They have thin bony walls and are shaped like pyramids whose base is the lateral wall of nasal cavity and whose apex is toward the zygomatic process of the maxilla., There are 4 paired sinuses in humans, all lined with pseudostratified columnar epithelium: the maxillary sinuses, the largest ones located under the eyes in the maxillary bones; the frontal sinuses, superior to the eyes within the frontal bone; the ethmoid sinuses, formed from several air cells within the ethmoid bone between the nose and eyes , Both nasal passages have inferior, middle, and superior (and sometimes another called "supreme") turbinates that severe multiple purposes, including direction of airflow, filtration, and sense of smell. There are four paired sinuses: maxillary sinuses, ethmoid sinuses, sphenoid sinuses, and frontal sinuses..