Lacrimal bone

View Related Images

Description:

This small, delicate, quadrate-shaped bone has a vertical axis that is slightly longer than its horizontal axis. It is extremely thin. When it is held up to a light source, the light easily penetrates the bone. The bone sits in the anterior part of the medial wall of the orbit. It has four margins and two surfaces. The margins are posterior, superior, anterior, and inferior. These margins form fine, butt-like sutures with neighboring bones. The surfaces are lateral or orbital and medial or nasal. The orbital surface is smooth and flat in its posterior half where it contributes to the medial wall of the orbit. Anteriorly this surface has a longitudinal groove that ends posteriorly in a longitudinal crest that is hook-shaped inferiorly. This groove supports the nasolacrimal duct. Covered with mucous membrane, the slightly rough, medial surface of the bone contributes to the nasal cavity.