The ethmoid bone (/ˈɛθmɔɪd/;[1][2] from Ancient Greek: ἡθμός, romanized: hēthmós, lit. 'sieve') is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction. The ethmoid bone is one of the bones that make up the orbit of the eye.
The ethmoid bone is an anterior cranial bone located between the eyes.[3] It contributes to the medial wall of the orbit, the nasal cavity, and the nasal septum.[3] The ethmoid has three parts: cribriform plate, ethmoidal labyrinth, and perpendicular plate. The cribriform plate forms the roof of the nasal cavity and also contributes to formation of the anterior cranial fossa,[4] the ethmoidal labyrinth consists of a large mass on either side of the perpendicular plate, and the perpendicular plate forms the superior two-thirds of the nasal septum.[3] Between the orbital plate and the nasal conchae are the ethmoidal sinuses or ethmoidal air cells, which are a variable number of small cavities in the lateral mass of the ethmoid.[5][6]
The ethmoid is ossified in the cartilage of the nasal capsule by three centers: one for the perpendicular plate, and one for each labyrinth.
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.
At birth, the bone consists of the two labyrinths, which are small and ill-developed. 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 cribriform plate is ossified partly from the perpendicular plate and partly from the labyrinths.
The development of the ethmoidal cells begins during fetal life.
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. Humans have a similar magnetite deposit (ferric iron), but it is believed to be vestigial.[7]
Clinical significanceedit
Fracture of the lamina papyracea, the lateral plate of the ethmoid labyrinth bone, permits communication between the nasal cavity and the orbit on the same side of the body through the inferomedial orbital wall, resulting in orbital emphysema. Increased pressure within the nasal cavity, as seen during sneezing, for example, leads to temporary exophthalmos.
The porous fragile nature of the ethmoid bone makes it particularly susceptible to fractures. The ethmoid is usually fractured from an upward force to the nose. This could occur by hitting the dashboard in a car crash or landing on the ground after a fall. The ethmoid fracture can produce bone fragments that penetrate the cribriform plate. This trauma can lead to a leak of cerebrospinal fluid into the nasal cavity. These openings let opportunistic bacteria in the nasal cavity enter the sterile environment of the central nervous system (CNS). The CNS is usually protected by the blood–brain barrier, but holes in the cribriform plate let bacteria get through the barrier. The blood–brain barrier makes it extremely difficult to treat such infections, because only certain drugs can cross into the CNS.
An ethmoid fracture can also sever the olfactory nerve. This injury results in anosmia (loss of smell). A reduction in the ability to taste is also a side effect because it is based so heavily on smell. This injury is not fatal, but can be dangerous, as when a person fails to smell smoke, gas, or spoiled food.[3] In fact, people with anosmia were more than four times as likely to die in five years compared to those with a healthy sense of smell.[8]
This section needs expansion. You can help by adding to it. (December 2013)
^Baker, R. Robin; Mather, Janice G.; Kennaugh, John H. (1983). "Magnetic bones in human sinuses". Nature. 301 (5895): 78–80. Bibcode:1983Natur.301...78R. doi:10.1038/301078a0. PMID 6823284. S2CID 2385818.
ethmoid, bone, ethmoid, bone, ɔɪ, from, ancient, greek, ἡθμός, romanized, hēthmós, sieve, unpaired, bone, skull, that, separates, nasal, cavity, from, brain, located, roof, nose, between, orbits, cubical, bone, lightweight, spongy, construction, ethmoid, bone,. The ethmoid bone ˈ ɛ 8 m ɔɪ d 1 2 from Ancient Greek ἡ8mos romanized hethmos lit sieve is an unpaired bone in the skull that separates the nasal cavity from the brain It is located at the roof of the nose between the two orbits The cubical bone is lightweight due to a spongy construction The ethmoid bone is one of the bones that make up the orbit of the eye Ethmoid boneEthmoid inside the orbit brown Animation of the ethmoid boneDetailsIdentifiersLatinos ethmoidaleMeSHD005004TA98A02 1 07 001TA2721FMA52740Anatomical terms of bone edit on Wikidata Contents 1 Structure 1 1 Articulations 1 2 Development 2 Function 2 1 Role in magnetoception 3 Clinical significance 4 Additional images 5 See also 6 References 7 Further reading 8 External linksStructure editThe ethmoid bone is an anterior cranial bone located between the eyes 3 It contributes to the medial wall of the orbit the nasal cavity and the nasal septum 3 The ethmoid has three parts cribriform plate ethmoidal labyrinth and perpendicular plate The cribriform plate forms the roof of the nasal cavity and also contributes to formation of the anterior cranial fossa 4 the ethmoidal labyrinth consists of a large mass on either side of the perpendicular plate and the perpendicular plate forms the superior two thirds of the nasal septum 3 Between the orbital plate and the nasal conchae are the ethmoidal sinuses or ethmoidal air cells which are a variable number of small cavities in the lateral mass of the ethmoid 5 6 Articulations edit The ethmoid articulates with thirteen bones two bones of the neurocranium the frontal and the sphenoid at the sphenoidal body and at the sphenoidal conchae eleven bones of the viscerocranium two nasal bones two maxillae two lacrimals two palatines two inferior nasal conchae and the vomer Development edit The ethmoid is ossified in the cartilage of the nasal capsule by three centers one for the perpendicular plate and one for each labyrinth 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 conchae At birth the bone consists of the two labyrinths which are small and ill developed 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 cribriform plate is ossified partly from the perpendicular plate and partly from the labyrinths The development of the ethmoidal cells begins during fetal life Function editRole in magnetoception edit Main article Magnetoception 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 Humans have a similar magnetite deposit ferric iron but it is believed to be vestigial 7 Clinical significance editFracture of the lamina papyracea the lateral plate of the ethmoid labyrinth bone permits communication between the nasal cavity and the orbit on the same side of the body through the inferomedial orbital wall resulting in orbital emphysema Increased pressure within the nasal cavity as seen during sneezing for example leads to temporary exophthalmos The porous fragile nature of the ethmoid bone makes it particularly susceptible to fractures The ethmoid is usually fractured from an upward force to the nose This could occur by hitting the dashboard in a car crash or landing on the ground after a fall The ethmoid fracture can produce bone fragments that penetrate the cribriform plate This trauma can lead to a leak of cerebrospinal fluid into the nasal cavity These openings let opportunistic bacteria in the nasal cavity enter the sterile environment of the central nervous system CNS The CNS is usually protected by the blood brain barrier but holes in the cribriform plate let bacteria get through the barrier The blood brain barrier makes it extremely difficult to treat such infections because only certain drugs can cross into the CNS An ethmoid fracture can also sever the olfactory nerve This injury results in anosmia loss of smell A reduction in the ability to taste is also a side effect because it is based so heavily on smell This injury is not fatal but can be dangerous as when a person fails to smell smoke gas or spoiled food 3 In fact people with anosmia were more than four times as likely to die in five years compared to those with a healthy sense of smell 8 This section needs expansion You can help by adding to it December 2013 Additional images edit nbsp Ethmoid bone from above nbsp Perpendicular plate of ethmoid nbsp Ethmoid bone view from behind nbsp Ethmoid bone from the right side nbsp Side view of the skull See also editThis article uses anatomical terminology References edit nbsp This article incorporates text in the public domain from page 153 of the 20th edition of Gray s Anatomy 1918 OED 2nd edition 1989 as ˈe8mɔɪd Entry ethmoid in Merriam Webster Online Dictionary a b c d Saladin Kenneth S 2015 Anatomy and Physiology the Unity of Form and Function 7th ed New York McGraw Hill ISBN 978 0 07 340371 7 Ethmoid bone www anatomynext com Archived from the original on 3 September 2020 Retrieved 1 March 2018 Fehrenbach Herring 2012 Illustrated Anatomy of the Head and Neck Elsevier p 52 Jacobs 2008 Human Anatomy Elsevier p 210 Baker R Robin Mather Janice G Kennaugh John H 1983 Magnetic bones in human sinuses Nature 301 5895 78 80 Bibcode 1983Natur 301 78R doi 10 1038 301078a0 PMID 6823284 S2CID 2385818 Pinto Jayant Wroblewski Kristen Kern David Schumm Phillip McClintock Martha 2014 Olfactory Dysfunction Predicts 5 Year Mortality in Older Adults PLOS One 9 10 e107541 Bibcode 2014PLoSO 9j7541P doi 10 1371 journal pone 0107541 PMC 4182669 PMID 25271633 Further reading editSaladin Kenneth S 2010 Anatomy and Physiology the Unity of Form and Function 5th ed New York McGraw Hill ISBN 978 0 07 128341 0 Banks Peter Brown Andrew E 2000 Fractures of the facial skeleton Oxford Wright ISBN 0 7236 1034 7 External links edit nbsp Wikimedia Commons has media related to Ethmoid bones http www theregister com 2006 11 17 the odd body nose compass Anatomy diagram 34256 000 1 Roche Lexicon illustrated navigator Elsevier Archived from the original on 27 December 2012 Portal nbsp Anatomy Retrieved from https en wikipedia org w index php title Ethmoid bone amp oldid 1221640860, wikipedia, wiki, book, books, library,
