a type of paranasal sinus (a hollow space in the bones around the nose). there are two, large frontal sinuses in the frontal bone, which forms the lower part of the forehead and reaches over the eye sockets and eyebrows. the frontal sinuses are lined with cells that make mucus to keep the nose from drying out.
出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/07/06 06:32 UTC 版)
Sinuses are mucosa-lined airspaces within the bones of the face and skull. The frontal sinuses, situated behind the superciliary arches, are absent at birth, but are generally fairly well developed between the seventh and eighth years, only reaching their full size after puberty. The frontal bone is membranous at birth and there is rarely more than a recess until the bone tissue starts to ossify about age two. Consequently this structure does not show on radiographs before that time. Frontal sinuses are rarely symmetrical and the septum between them frequently deviates to one or other side of the middle line. Sinus development begins in the womb, but only the maxillary and ethmoid sinuses are present at birth. Approximately 5% of people have absent frontal sinuses.