Lacrimal bone

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Lacrimal bone
Position of the lacrimal bone (shown in green).
Medial wall of the orbit. Lacrimal bone is in yellow.
Details
Identifiers
Latinos lacrimale
TA98A02.1.09.001
TA2744
FMA52741
Anatomical terms of bone

The lacrimal bones are two small and fragile

runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways.[1][2]

Structure

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

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

anterior ethmoidal cells
.

Borders

Of the four borders:

Development

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 neurocranium, the frontal and ethmoid, and two of the viscerocranium, the maxilla and the inferior nasal concha.

Other animals

Lacrimal bone in the reptile Lazarussuchus

In early

lobe-finned fishes 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 bones 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 amphibians, as well as some reptilian species.[3]

Dinosaurs

In dinosaurs, the lacrimal bone usually defines the anterior rim of the orbit (eye socket), and the posterior rim of the

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.[4]

Additional images

  • Position of the lacrimal bones (shown in green). Animation.
    Position of the lacrimal bones (shown in green). Animation.
  • Animation. Some bones are removed to show the position of the lacrimal bones (shown in green).
    Animation. Some bones are removed to show the position of the lacrimal bones (shown in green).
  • Orbital bones. Lacrimal bone shown in green.
    Orbital bones. Lacrimal bone shown in green.
  • A left lacrimal bone. Enlarged. Animation.
    A left lacrimal bone. Enlarged. Animation.
  • Lacrimal bone
    Lacrimal bone
  • Lacrimal bone
    Lacrimal bone

See also

This article uses anatomical terminology.

References

  1. PMID 24743297
    .
  2. ISBN 978-0-07-340371-7.[page needed
    ]
  3. ISBN 0-03-910284-X
    .
  4. S2CID 85354215
    .

External links

Wikimedia Commons has media related to Lacrimal bones.
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