[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) › Cribriform plate [Skeletal system](https://durgical.com/en/anatomy/system/skeletal-system/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) # Cribriform plate The cribriform plate is the thin, sieve-like roof of the nose, part of the ethmoid; it lets the smell nerves through, and a fracture can leak brain fluid. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=head_neck&select=cribriform_plate&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The sieve-like roof of the nose, part of the ethmoid. ## What it does Lets the smell nerves through; a fracture here can leak brain fluid from the nose. ## Key points - The olfactory filaments pass through it wrapped in sleeves of dura and arachnoid, a direct path between the nose and the subarachnoid space: hence CSF leaks and meningitis after fractures - The lateral lamella that joins it to the ethmoid roof is the thinnest bone of the skull base; its height varies (Keros types 1 to 3) and a deep olfactory fossa is at greater risk in sinus surgery - CSF rhinorrhoea after trauma may start days later and often increases when the head is bent forward; loss of smell may be on one or both sides ## Key facts **Where** [Ethmoid bone](https://durgical.com/en/anatomy/ethmoid-bone/), roof of the nasal cavity, either side of the crista galli **Function** Olfactory nerve fibres pass through; fracture can cause CSF rhinorrhoea and loss of smell ## Relations **Contents** [Olfactory nerve](https://durgical.com/en/anatomy/olfactory-nerve/) filaments (bundles of receptor axons) from the olfactory mucosa to the olfactory bulb; the anterior ethmoidal nerve and vessels pass through a slit beside the crista galli **Above** Olfactory bulbs on each side of the crista galli, beneath the gyri recti of the frontal lobes **Below** Roof of the [nasal cavity](https://durgical.com/en/anatomy/nasal-cavity/) with the olfactory mucosa, in the narrow cleft between the [nasal septum](https://durgical.com/en/anatomy/nasal-septum/) and the superior concha **Lateral** [Ethmoid cells](https://durgical.com/en/anatomy/anterior-cells-of-ethmoid-bone/); the thin lateral lamella rises from its edge to the ethmoid roof (fovea ethmoidalis), formed by the [frontal bone](https://durgical.com/en/anatomy/frontal-bone/) and lying higher **Medial** Crista galli in the midline, anchoring the [falx cerebri](https://durgical.com/en/anatomy/falx-cerebri/) ## How to find it It cannot be felt. On coronal CT it is the thin horizontal plate on each side of the crista galli, lower than the ethmoid roof beside it; the drop between the two (olfactory fossa depth) is read before endoscopic sinus surgery. ## Examination - Smell testing one nostril at a time, with familiar odours or a standardised kit: loss after a head injury suggests shearing of the filaments at the plate - Halo (double ring) sign: a drop of bloody nasal fluid on gauze or filter paper spreading with a clear outer ring suggests CSF; it is not specific, and laboratory testing of the fluid confirms it ## On imaging Thin coronal CT shows the plate, fractures and a bony gap at a leak site; CT cisternography or heavily T2-weighted MRI helps locate an active CSF leak or an encephalocele. ## Clinical notes - In endoscopic sinus surgery the lateral lamella is the classic site of an accidental breach of the skull base and CSF leak - Olfactory groove meningioma grows on the plate: loss of smell and slow personality change; with optic atrophy on one side and papilloedema on the other it forms Foster Kennedy syndrome - Spontaneous CSF leaks and meningoencephaloceles occur here, often linked to raised intracranial pressure - Olfactory neuroblastoma (esthesioneuroblastoma) arises from the olfactory mucosa next to the plate and can invade through it into the skull ## Development The ethmoid has no bony cribriform plate at birth; the plate ossifies during the first years, partly from the labyrinths and partly from the centre of the perpendicular plate. A midline nasal mass in an infant can connect to the cranial cavity through the still-forming skull base, so it is imaged before any biopsy. ## Related conditions - [Free-living amoeba infections (Naegleria meningoencephalitis, Acanthamoeba)](https://durgical.com/en/conditions/free-living-amoeba-infections/) - [Basilar skull fracture](https://durgical.com/en/conditions/basilar-skull-fracture/) - [Bacterial meningitis](https://durgical.com/en/conditions/bacterial-meningitis/) ## Test yourself Think of the answer, then tap the question to see it. ## What passes through the cribriform plate? The olfactory nerve filaments, from the olfactory mucosa to the olfactory bulb. ## Why does a cribriform plate fracture risk meningitis? The olfactory filaments pass through it in sleeves of dura and arachnoid, a direct path between the nose and the subarachnoid space. ## What is the halo sign in suspected CSF rhinorrhoea from a cribriform plate fracture? Bloody nasal fluid on gauze spreads with a clear outer ring; it suggests CSF but is not specific, so laboratory testing confirms it. ## Which bone beside the cribriform plate is the classic site of a skull base breach in sinus surgery? The lateral lamella, the thinnest bone of the skull base; a deep olfactory fossa (higher Keros type) is at greater risk. ## What is Foster Kennedy syndrome from an olfactory groove meningioma on the cribriform plate? Loss of smell with optic atrophy on one side and papilloedema on the other. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/anatomy/cribriform-plate/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** lamina cribrosa TA2 722 **Official Spanish (DeCS)** Lámina cribosa del etmoides **English (TA2)** Cribriform plate **Also called** lamina cribriformis ## Related - [Olfactory nerve (I)](https://durgical.com/en/anatomy/olfactory-nerve/) Sources: Terminologia Anatomica (TA2); [Cribriform Plate Fractures](https://www.ncbi.nlm.nih.gov/books/NBK562192/); [Anatomy, Head and Neck, Ethmoid Bone](https://www.ncbi.nlm.nih.gov/books/NBK544328/); Anatomy of the Human Body (20th ed.): Ethmoid Bone (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain. ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/cribriform-plate/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/cribriform-plate/