User:SSergeant/Ethmoid bone

“Ethmos” is derived from the word ethmoid, this means sieve, then depicted lightweight, spongy structure. The ethmoid bone is an unpaired small bone, its located within the midline of the anterior cranium, looking from above the cranium the bone encloses the skull and protects the brain. In most organisms its located in or around the same area, with the cribriform plate lying above the nasal cavity; however there are still some organisms in which their structures are different. For instance, in rats the cribriform plate lies behind the nasal cavity instead. There are a lot of nerve fibres that pases through the cribiform plate in the ethmoid bone that gives the nasal cavity the sense of smell. This is located between two orbital cavities, at the roof of the nasal cavity. When in the orbit of the medial wall it forms the anterior cranial fossa separating the inferiorly nasal cavity from the superiorly cranial cavity. This forms a great portion of the nasal septum and the lateral nasal wall. This bone is made up of the cribriform plate, perpendicular plate, and the ethmoidal labyrinth. The cribriform plate is located between the anterior cranial fossa and the nasal cavity, it as well supports the olfactory bulb which lays within the olfactory fossa. The perpendicular plate is  thin lamin which is under the cribriform plate, helping to create 2/3 of the septum in the nose. The ethmoidal labyrinth is the lateral mass of the ethmoid bone; this includes the cellular cavities, air cells, anterior,posterior and middle groups of 2 vertical plates consisting of bone. The middle bone is used to help work with the nasal cavity. When the lateral and medial plates are working corresponding to each other they close at every part except when they need to be opened for the nasal cavity. From the cribriform plate the crista galli is formed which provides an attachment for the falx cerebri. The orbital plate helps to form the medial wall of orbit. The medial sheet derives from the lateral wall at the top of the nasal cavity. The paired bones include nasal bones, lacrimal bones and maxillae. The unpaired bones include the frontal and the sphenoid bones. The ethmoid bone overall gives proof of the distribution of the olfactory organ size (OOS) in mammals. Since the olfactory bulb has 5 layers (the glomerular layer, external plexiform layer, the mitral layer, granule layer and the olfactory layer) it is located on the cribriform plate of the ethmoid bone, (frontal lobe,ventral surface) where there's a surrounding layer of pia-arachnoid cells.