The development of the ethmoidal cells begins during fetal life. The cribriform plate is ossified partly from the perpendicular plate and partly from the labyrinths. During the first year after birth, the perpendicular plate and crista galli begin to ossify from a single center, and are joined to the labyrinths about the beginning of the second year. The labyrinths are first developed, ossific granules making their appearance in the region of the lamina papyracea between the fourth and fifth months of fetal life, and extending into the conchæ.Īt birth, the bone consists of the two labyrinths, which are small and ill-developed. The ethmoid is ossified in the cartilage of the nasal capsule by three centers: one for the perpendicular plate, and one for each labyrinth. Humans have a similar magnetite deposit, but it is believed to be vestigial. Some birds and other migratory animals have deposits of biological magnetite in their ethmoid bones which allow them to sense the direction of the Earth's magnetic field. Role in magnetoception Main article: Magnetoception This not only deprives life of some of its pleasures, but can also be dangerous, as when a person fails to smell smoke, gas, or spoiled food. Such injuries are often evidenced by leakage of cerebrospinal fluid into the nasal cavity, and may be followed from the nasal cavity to the brain.īlows to the head can also shear off the olfactory nerves that pass though the ethmoid bone and cause anosmia, an irreversible loss of the sense of smell and a great reduction in the sense of taste (most of which depends on smell). The force of a blow can drive bone fragments through the cribiform plate into the meninges or brain tissue. The ethmoid bone is very delicate and is easily injured by a sharp upward blow to the nose, such as a person might suffer by striking an automobile dashboard in a collision. The ethmoid articulates with fifteen bones: four of the cranium-the frontal, the sphenoid, and the two sphenoidal chonchae and eleven of the face-the two nasals, two maxillae, two lacrimals, two palatines, two inferior nasal conchae, and the vomer. the vertical Perpendicular plate ( lamina perpendicularis), which is part of the nasal septum.the horizontal Cribriform plate ( lamina cribrosa), part of the cranial base.
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