| Cribriform plate | |
|---|---|
 Superior view of the central part of theanterior cranial fossa.CG:crista galli; CF: cribriform plate | |
 1:Olfactory bulb 2:Mitral cells 3: Cribriform plate 4:Olfactory epithelium 5:Glomerulus 6:Olfactory receptor neurons | |
| Details | |
| Part of | Ethmoid bone of thehuman skull |
| System | Skeletal |
| Identifiers | |
| Latin | lamina cribrosa ossis ethmoidalis |
| TA98 | A02.1.07.002 |
| TA2 | 722 |
| FMA | 52890 |
| Anatomical terms of bone | |
Inmammalian anatomy, thecribriform plate (Latin forlit.sieve-shaped),horizontal lamina orlamina cribrosa is part of theethmoid bone. It is received into theethmoidal notch of thefrontal bone and roofs in thenasal cavities. It supports theolfactory bulb, and is perforated byolfactory foramina for the passage of theolfactory nerves to the roof of thenasal cavity to convey smell to the brain. The foramina at themedial part of the groove allow the passage of the nerves to the upper part of thenasal septum while the foramina at the lateral part transmit the nerves to thesuperior nasal concha.
A fractured cribriform plate can result inolfactory dysfunction,septal hematoma,cerebrospinal fluid rhinorrhoea (CSF rhinorrhoea), and possibly infection which can lead tomeningitis. CSF rhinorrhoea (clear fluid leaking from the nose) is very serious and considered amedical emergency. Aging can cause the openings in the cribriform plate to close, pinching olfactory nerve fibers. A reduction in olfactory receptors, loss of blood flow, and thick nasal mucus can also cause an impaired sense of smell.[1]
The cribriform plate is part of theethmoid bone, which has a low density, and is spongy.[2] It is narrow, with deep grooves supporting theolfactory bulb.
Its anterior border, short and thick, articulates with thefrontal bone. It has two small projecting alae (wings), which are received into corresponding depressions in the frontal bone to complete theforamen cecum.
Its sides are smooth, and sometimes bulging due to the presence of a smallair sinus in the interior.
Thecrista galli projects upwards from the middle line of the cribriform plate. The long thin posterior border of the crista galli serves for the attachment of thefalx cerebri. On either side of the crista galli, the cribriform plate is narrow and deeply grooved. At the front part of the cribriform plate, on either side of the crista galli, is a small fissure that is occupied by a process ofdura mater.
Lateral to this fissure is a notch or foramen which transmits thenasociliary nerve; from this notch a groove extends backward to the anterior ethmoidal foramen.
The cribriform plate is formed from the fetal age to the end of the first year, completing ossification. Deriving from the nasal capsule, formation begins specifically during the 5th week of gestation. Ossification begins at its most anterior part and proceeds in a posterior manner. The position also shifts from vertical during the 1st postnatal month to horizontal at the age of 6 months.
The Keros classification is a method of classifying the depth of the olfactory fossa.
The depth of the olfactory fossa is determined by the height of the lateral lamella of the cribriform plate.Keros in 1962, classified the depth into three categories.[3]
The cribriform plate is perforated byolfactory foramina, which allow for the passage of theolfactory nerves to the roof of thenasal cavity.[4] This conveys information from smell receptors to thebrain. The foramina at themedial part of the groove allow the passage of the nerves to the upper part of thenasal septum while the foramina at the lateral part transmit the nerves to thesuperior nasal concha.
A fractured cribriform plate (anterior skull trauma) can result in leaking ofcerebrospinal fluid into the nose andloss of sense of smell. The tiny apertures of the plate transmitting the olfactory nerve become the route of ascent for a pathogen,Naegleria fowleri. Thisamoeba tends to destroy the olfactory bulb and the adjacent inferior surface of the frontal lobe of the brain. This surface initially becomes the site of proliferation of thetrophozoites ofNaegleria fowleri and their subsequent spread to the rest of the brain and CSF. Because of its initial involvement and trophozoite presence in early phases ofNaegleria fowleri infection, flushing of this region with saline using a device, to obtainNaegleria fowleri for diagnostic PCR and microscopic viewing, has been proposed for patients affected bynaegleriasis, by (Baig AM., et al.) in a recent publication.[5] Researchers have suggested the same route to administer drugs at an early phase of infection by using a "Transcribrial Device"[6] that has been proposed to kill this pathogen at the place of its maximum proliferation. In 2017 the inventor of this device suggested that after slight modifications this method could be effective in delivery of stem cells to the brain as well.[7] A recent Australian study has shown that the bacterium causing the tropical diseasemelioidosis,Burkholderia pseudomallei, can also invade the brain via the olfactory nerve within 24 h by traversing the cribriform plate.[8]
The cribriform plate is named after its resemblance to a sieve (from Latincribrum, "sieve" + -form).[2] It is also known as the horizontal lamina, and the lamina cribrosa.
The cribriform plate is found in everymammal that has been studied.[9] It serves the same function of allowing passage of theolfactory nerves.[9]
This article incorporates text in thepublic domain frompage 153 of the 20th edition ofGray's Anatomy(1918)
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