Nasal bone

At a glance

English

Nasal bone

Latin (TA2)

Os nasale

System

Bone

Region

Head

Side

Paired, left and right

About the nasal bone

The two nasal bones are small, oblong plates set side by side between the eyes, at the top of the middle of the face. Meeting each other at the internasal suture, they form the bony bridge that makes up roughly the upper third of the nose; below them the shape of the nose depends on cartilage. Their size and outline differ a good deal from one person to another.

Each bone has an outer and an inner surface and four borders. The outer surface is curved: concave then convex along its length and convex across, and the procerus and nasalis muscles lie over it. Near its middle a tiny foramen lets a small vein pass through. The inner surface faces the nasal cavity, is hollowed from side to side, and carries a vertical groove for the external nasal branch of the anterior ethmoidal nerve, which continues the nasociliary nerve.

Each nasal bone has four neighbours. Above, a thick serrated edge locks into the nasal notch of the frontal bone. Behind, it leans on the spine of the frontal bone and the perpendicular plate of the ethmoid, which hold it up. Laterally it meets the frontal process of the maxilla, and medially it meets its partner. The thin lower border gives attachment to the upper lateral cartilage of the nose.

Sticking out from the face and thin at their lower ends, the nasal bones are the facial bones most often broken. A fracture tends to push the bridge to one side or flatten it and may tear the lining of the nose, causing a nosebleed; a swelling of blood under the septum needs prompt drainage.

Function and supply

Function

Gives the upper nose a rigid roof, protecting the nasal cavity and supporting the cartilages that shape the lower nose.

Nerve supply

Not innervated as a muscle is; the external nasal branch of the anterior ethmoidal nerve runs in a groove on its inner surface and supplies the skin over the lower nose.

Blood supply

Supplied through its periosteum by the dorsal nasal branch of the ophthalmic artery and the anterior ethmoidal artery; a small vein crosses the bone through the nasal foramen.