These are two oblong bones situated in the middle line at the upper part of the face and forming the bridge of the nose. Each bone has two surfaces and four borders. The facial surface is concave from above downwards, but convex from side to side. Near its centre is a foramen for the transmission of a small tributary to the facial vein. The posterior or nasal surface is concave laterally and traversed by a longitudinal groove for the nasal branch of the ophthalmic nerve.
In life this surface has a covering of a mucous membrane. The short superior border is thick and serrated for articulation with the nasal notch of the frontal. The inferior border is thin and serves for the attachment of the lateral nasal cartilages. Each bone articulates with its fellow by the median border, which is prolonged backwards to form a crest; this crest comes into relation with the nasal spine of the frontal and the anterior border of the mesethmoid. The outer border articulates with the nasal process of the maxilla.
The nasal bone articulates with its fellow, the frontal, maxilla and ethmoid.
Twigs to this bone are furnished by the nasal branch of the ophthalmic, the frontal, the angular and the anterior ethmoidal arteries.
The Left Nasal Bone.
Each nasal bone is developed from a single earthy nucleus in the membrane overlying the frontonasal cartilage. The nucleus is easily seen in the eighth week. The bone by its pressure soon produces absorption of the underlying cartilage. At birth the nasal bones are nearly as wide as they are long, whereas in the adult the length of the bones is three times greater than the width.