The Nasal Bone
The nasal bones are two small bones of the midface which build the bridge of the nose.
The nasal bone is a bilateral symmetrical paired bone of the face. Their superior borders and main bodies form the bridge of the nose while the inferior borders connect with the nasal cartilage to form the superior margin of the nasal aperture.
It is bordered medially by its pair (→the internasal suture), the nasal part of the frontal bone superiorly (→frontonasal suture) and laterally by the frontal process of the maxilla (→ nasomaxillary suture). The perpendicular plate of the ethmoid bone (→ nasoethmoidal suture) and the septal cartilage of the nose lie behind the nasal bones. Inferiorly it is attached to the lateral cartilage of the nose.
The nasal bones are ossified intramembranously via the cartilaginous nasal capsule. Clinically the hypoplasia or absence of nasal bones is a common feature in Down syndrome (trisomy 21) and other chromosomal abnormalities. That is why the detection of the nasal tip in the ultrasound has become part of prenatal screening tests in many countries.
The nose is an extremely frequent place for fractures, e.g. due to sports injuries, road traffic accidents and fist fights. One typical example is the Le Fort II fracture: It has a pyramidal-shaped outline and extends from the nasal bridge superiorly to the pterygoid plates inferiorly. Laterally it passes through the inferior orbital floor and the anterior wall of the maxillary sinus. Within the orbit the fracture line passes next to the infraorbital foramen where the infraorbital nerve and its corresponding vessels pass through. As it requires a great force to cause a Le Fort fracture the affected patients ought to be checked on other injuries as well, e.g. up to 50% have an open fracture with leaking cerebrospinal fluid.
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