The lacrimal bone is a small and fragile
bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and ...
of the
facial skeleton The facial skeleton comprises the ''facial bones'' that may attach to build a portion of the skull. The remainder of the skull is the braincase. In human anatomy and development, the facial skeleton is sometimes called the ''membranous visceroc ...
; it is roughly the size of the little fingernail. It is situated at the front part of the medial wall of the
orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...
. It has two surfaces and four borders. Several bony landmarks of the lacrimal bone function in the process of lacrimation or crying. Specifically, the lacrimal bone helps form the nasolacrimal canal necessary for tear translocation. A depression on the anterior inferior portion of the bone, the lacrimal fossa, houses the membranous lacrimal sac. Tears or lacrimal fluid, from the lacrimal glands, collect in this sac during excessive lacrimation. The fluid then flows through the nasolacrimal duct and into the nasopharynx. This drainage results in what is commonly referred to a runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways.


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 The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. Th ...
, and the lacrimal fossa is thus completed. The upper part of this fossa lodges the
lacrimal sac The lacrimal sac or lachrymal sac is the upper dilated end of the nasolacrimal duct, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla. It connects the lacrimal canaliculi, which drain tears from the ...
, the lower part, the
nasolacrimal duct The nasolacrimal duct (also called the tear duct) carries tears from the lacrimal sac of the eye into the nasal cavity. The duct begins in the eye socket between the maxillary and lacrimal bones, from where it passes downwards and backwards. ...
. 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 The orbicularis oculi is a muscle in the face that closes the eyelids. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a shor ...
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. The area behind it articulates with the ethmoid, and completes some of the anterior ethmoidal cells.


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.


The lacrimal is ossified from a single center, which appears about the twelfth week in the membrane covering the cartilaginous nasal capsule.


The lacrimal articulates with four bones: two of the cranium, the
frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * '' The Front'', 1976 film Music * The Front (band), an American rock band signed to Columbia Records and active in the 1980s and ...
and ethmoid, and two of the face, the
maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. Th ...
and the inferior nasal concha.

Other animals

In early
lobe-finned fish Sarcopterygii (; ) — sometimes considered synonymous with Crossopterygii () — is a taxon (traditionally a class or subclass) of the bony fishes known as the lobe-finned fishes. The group Tetrapoda, a mostly terrestrial superclass inclu ...
es and ancestral tetrapods, the lacrimal bone is a relatively large and robust bone, running from the orbit to the nostrils. It forms part of the side of the face, between the
nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...
s and the maxilla. In primitive forms, it is often accompanied by a much smaller septomaxilla bone, lying immediately behind the nasal opening, but this is lost in most modern species. The lacrimal bone is often smaller in living vertebrates, and is no longer always directly associated with the nasal opening, although it retains its connection with the orbit. The bone is entirely absent in living
amphibian Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arb ...
s, as well as some reptilian species.


In dinosaurs, the lacrimal bone usually defines the anterior rim of the orbit (eye socket), and the posterior rim of the antorbital fenestra. In some theropods (e.g. ''
Allosaurus ''Allosaurus'' () is a genus of large carnosaurian theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic epoch (Kimmeridgian to late Tithonian). The name "''Allosaurus''" means "different lizard" alluding to ...
'', ''
Ceratosaurus ''Ceratosaurus'' (from Greek κέρας/κέρατος, ' meaning "horn" and σαῦρος ' meaning "lizard") was a carnivorous theropod dinosaur in the Late Jurassic period (Kimmeridgian to Tithonian). The genus was first described in 1884 ...
'', '' Albertosaurus'') the upper part of the lacrimal bone grew in such a manner as to form a horn on the top of the dinosaur's head, usually situated above, and anterior to the eye. In many dinosaurs, the lacrimal bone comes into contact with the nasal bone, the jugal bone, the prefrontal bone, and the maxillary and premaxillary bones. The boundaries where some of these bones meet with the others are called sutures. Rarely, the lacrimal bones fused with the nasal bones to form a pair of "nasolacrimal" crests, which are present in dinosaurs such as '' Dilophosaurus'', '' Megapnosaurus'' and '' Sinosaurus''.

Additional images

File:Lacrimal bone - animation.gif, Position of the lacrimal bones (shown in green). Animation. File:Lacrimal bone - animation3.gif, Animation. Some bones are removed to show the position of the lacrimal bones (shown in green). File:Orbital bones.png, Orbital bones. Lacrimal bone shown in green. File:Left lacrimal bone - close-up - animation.gif, A left lacrimal bone. Enlarged. Animation. File:Orbital cavity.jpg, Lacrimal bone File:Slide7llll.JPG, Lacrimal bone

See also


External links

* * *
Diagram at upstate.edu
{{Authority control Bones of the head and neck Irregular bones Flat bones