Lacrimal bone 321727 195761478 2008-03-04T08:53:59Z 203.198.195.13 {{Infobox Bone | Name = {{PAGENAME}} | Latin = os lacrimale | GraySubject = 39 | GrayPage = 164 | Image = Gray164.png | Caption = Lacrimal bone visible near center. | Image2 = Orbital bones.png| | Caption2 = Orbital bones | Articulations = | MeshName = | MeshNumber = | DorlandsPre = | DorlandsSuf = | }} The '''lacrimal bone''', the smallest and most fragile [[bone]] of the face, is situated at the front part of the medial wall of the [[Orbit (anatomy)|orbit]]. It has two surfaces and four borders. == Surfaces == === Lateral or orbital surface === The lateral or orbital surface is divided by a vertical ridge, the [[posterior lacrimal crest]], into two parts. In ''front'' of this crest is a longitudinal groove, the [[lacrimal sulcus]] (''sulcus lacrimalis''), the inner margin of which unites with the frontal process of the [[maxilla]], and the lacrimal fossa is thus completed. The upper part of this [[fossa]] lodges the [[lacrimal sac]], the lower part, the [[nasolacrimal duct]]. The portion ''behind'' the crest is smooth, and forms part of the medial wall of the orbit. The crest, with a part of the orbital surface immediately behind it, gives origin to the lacrimal part of the [[Orbicularis oculi]] and ends below in a small, hook-like projection, the [[lacrimal hamulus]], which articulates with the [[lacrimal tubercle of the maxilla]], and completes the upper orifice of the [[nasolacrimal canal]]; the hamulus sometimes exists as a separate piece, and is then called the [[lesser lacrimal bone]]. === Medial or nasal surface === The medial or nasal surface presents a longitudinal furrow, corresponding to the crest on the lateral surface. The area in front of this furrow forms part of the middle [[meatus]] of the nose; that behind it articulates with the [[ethmoid]], and completes some of the [[anterior ethmoidal cells]]. == Borders == Of the four borders: * the ''anterior'' articulates with the frontal process of the maxilla; * the ''posterior'' with the [[lamina papyracea]] of the ethmoid; * the ''superior'' with the frontal bone. * The ''inferior'' is divided by the lower edge of the posterior lacrimal crest into two parts: ** the posterior part articulates with the orbital plate of the maxilla; ** the anterior is prolonged downward as the descending process, which articulates with the lacrimal process of the [[inferior nasal concha]], and assists in forming the canal for the nasolacrimal duct. == Ossification == The lacrimal is ossified from a single center, which appears about the twelfth week in the membrane covering the cartilaginous nasal capsule. == Articulations == The lacrimal articulates with ''four'' bones: two of the cranium, the [[frontal bone|frontal]] and [[ethmoid bone|ethmoid]], and two of the face, the [[maxilla]] and the inferior nasal concha. ==Additional images== <center> <gallery> Image:Gray163.png|Left lacrimal bone. Orbital surface. Enlarged Image:Gray188.png|Side view of the skull. Image:Gray190.png|The skull from the front. Image:Gray192.png|Medial wall of left orbit. Image:Gray196.png|Roof, floor, and lateral wall of left nasal cavity. </gallery></center> == See also == *[[Bone#Terminology|Bone terminology]] *[[Terms for anatomical location]] ==External links== * {{eMedicineDictionary|Lacrimal+bone}} * {{UMichAtlas|eye_5}} * {{UMichAtlas|rsa2p4}} * {{RocheLexicon|34256.000-1}} * [http://www.upstate.edu/cdb/grossanat/hnskullantlb.shtml Diagram at upstate.edu] {{OrbitalBones}} {{Facial bones}} [[Category:Skeletal system]] [[Category:Skull]] [[ar:عظم دمعي]] [[ca:Unguis]] [[de:Tränenbein]] [[es:Unguis]] [[fr:Os lacrymal]] [[ja:涙骨]] [[lv:Asaru kauls]] [[lt:ašarikaulis]] [[pl:Kość łzowa]] [[pt:Osso lacrimal]] [[sk:Slzná kosť]] [[sl:Solznica]] [[uk:Слізна кістка]] [[zh:淚骨]]