Nasal Bone
Os Nasale
location_on Superior bridge of the nose, between the frontal processes of the maxillae
The paired nasal bones are small, oblong bones that form the bridge of the nose. They articulate with each other in the midline, with the frontal bone superiorly, and with the maxillae laterally. Despite their small size, nasal bone fractures are the most common fracture of the face. The nasal bones vary considerably in size and shape between individuals and populations.
Key Anatomical Features
- Internasal suture joins the two nasal bones in the midline
- Nasion is the craniometric point at the intersection of the internasal and nasofrontal sutures
- External surface is concavoconvex and perforated by a small foramen for a vein
- Internal surface has a longitudinal groove for the anterior ethmoidal nerve
- Inferior border is thin and gives attachment to the lateral nasal cartilage
Muscle Attachments
| Muscle | Attachment | Action |
|---|---|---|
| Procerus | Lower portion of nasal bone and upper lateral nasal cartilage | Wrinkles the skin over the bridge of the nose, pulls eyebrows down |
| Nasalis (transverse part) | Near the nasal bone on the maxilla | Compresses the nasal aperture |
| Levator labii superioris alaeque nasi | Frontal process of maxilla adjacent to nasal bone | Elevates the upper lip and dilates the nostril |
| Depressor septi nasi | Inferior to nasal bone on maxilla | Pulls the nasal septum inferiorly |
Joints and Articulations
| Joint | Type | Connects to |
|---|---|---|
| Internasal suture | Fibrous suture | Opposite nasal bone |
| Nasofrontal suture | Fibrous suture | Frontal bone |
| Nasomaxillary suture | Fibrous suture | Maxilla |
Common Pathologies
Nasal fracture
The most common facial fracture, usually from direct trauma. May be simple or comminuted and often associated with septal fracture or deviation.
Septal hematoma
Collection of blood beneath the mucoperichondrium of the nasal septum that can occur with nasal bone fracture. If untreated, it can cause septal abscess and cartilage necrosis leading to saddle nose deformity.
Naso-orbito-ethmoidal fracture
Complex fracture involving the nasal bones, ethmoid, and medial orbital walls. Can damage the medial canthal ligaments causing telecanthus (widening of the intercanthal distance).
Clinical Relevance
Nasal fractures are diagnosed clinically rather than radiographically in most cases. Always examine for septal hematoma after nasal trauma, as untreated hematoma can destroy the septal cartilage within 72 hours. The nasion serves as an important craniometric landmark used in cephalometric analysis for orthodontic treatment planning.
Development and Ossification
Each nasal bone ossifies intramembranously from a single center that appears around the 8th fetal week. The nasal bones are fully formed at birth but continue to grow in length and width until puberty.
Did You Know?
- Nasal bone fractures account for about 40% of all facial fractures
- The nasal bones only form the upper third of the nose; the lower two-thirds is cartilage
- Nasal bone shape varies significantly among populations and is one of the features used in forensic anthropology to estimate ancestry
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