Lacrimal bone

Os lacrimale

The smallest and most fragile facial bone, a thin plate in the anterior medial wall of the orbit that helps form the fossa for the lacrimal sac.

Show on body map Skull — Lateral View

Overview

Each lacrimal bone is about the size of a fingernail. Its orbital surface is divided by a vertical posterior lacrimal crest: in front of it the lacrimal groove, together with the frontal process of the maxilla (anterior lacrimal crest), forms the fossa for the lacrimal sac, which leads down into the nasolacrimal canal; behind it the bone continues the medial orbital wall. The lacrimal part of orbicularis oculi arises from the posterior crest, pressing the sac to pump tears. Its medial surface forms part of the lateral wall of the nasal cavity, covering anterior ethmoidal cells.

Location: Anterior part of the medial orbital wall, behind the frontal process of the maxilla.

Parts & subdivisions

Posterior lacrimal crest
Vertical ridge; origin of the lacrimal part of orbicularis oculi.
Lacrimal groove
Forms the fossa for the lacrimal sac with the maxilla.
Lacrimal hamulus
Hook-like process curving around the upper nasolacrimal canal.

Anatomy

Articulations: Frontal, ethmoid, maxilla and inferior nasal concha.
Ossification: Intramembranous, single centre ≈week 12.

Function

Houses the lacrimal sac and begins the nasolacrimal canal for tear drainage
Forms part of the medial orbital wall and lateral nasal wall

Clinical significance

Dacryocystorhinostomy (DCR)

For nasolacrimal duct obstruction, a window is made through the thin lacrimal bone to drain the lacrimal sac directly into the nasal cavity.

Compiled from standard anatomy and physiology references — see the Skeletal System sources. For education only; not medical advice.