The lacrimal bone is a paired rectangular-shaped bone that lies anteriorly in the medial wall of the orbit between the frontal process of the maxilla and the ethmoid bone. It is the smallest bone of the ones forming the skull.

Each lacrimal bone has two surfaces - lateral and medial, and four borders - anterior, posterior, superior and inferior.

Surfaces of lacrimal bone

The lateral surface forms the medial wall of the orbit, so it is also called the orbital surface.

This surface contains several anatomical landmarks, such as:

Posterior lacrimal crest - a vertical ridge in the middle of the surface;
Lacrimal groove - located anterior to the crest; participates in forming the nasolacrimal canal;
Lacrimal fossa - located inferior to the groove, it is formed by the union of the frontal process of the maxilla; the fossa contains the lacrimal sac superiorly and the nasolacrimal duct on its inferior part.

The lacrimal part of the orbicularis oculi muscle is attached to the lateral surface of the lacrimal bone. The lateral surface contains an extension similar to a hook. Therefore it is called the lacrimal hooklet or also hamulus. It articulates with the maxilla.

Borders of lacrimal bone

The medial surface is also referred to as the nasal surface as it faces the nasal cavity. This surface forms a small part of the middle nasal meatus and also encloses ethmoidal air cells as it has an articulation with the ethmoid bone.

As mentioned above, the anterior border connects with the frontal process of the maxilla, the superior border articulates with the frontal bone, while the posterior border has a connection with the ethmoidal bone.

The posterior aspect of the inferior border articulates with the maxilla, but the anterior portion has an extension going in the inferior direction called the descending process, which articulates with the inferior nasal concha.

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Lacrimal bone