Nasal Bone: Definition, Structure, & Function

Nasal Bone Definition

A paired flat bone located at the upper third of the nose bridge is called the nasal bone. It is rectangular in shape and consists of four borders with the internal and external surface.

The holes present in these bones allow veins to pass through from the skin. Cartilage is attached to the thinner inferior end of the nasal bone. The lower two-thirds of the nose takes place by the cartilage.

Nasal Bone Anatomy

The bone found in pairs and are near-symmetrical bones. The bones can be easily located at the top of the nose. The glabella is the part between the eyebrows where the narrow border of bone articulates with the frontal bone.

The frontonasal suture is the point where the bones meet. At the nasomaxillary suture, the outer, long border of nasal bone meets the frontal process of the maxilla bone. The same border of another nasal bone located on the other side of the nasal septum also articulates with the medial border.

The internasal suture is the point where the twin bones join with each other. The lower border of the inferior border joins with the upper lateral nasal cartilage. The nasal bone, inferior nasal concha bone, medial nasal concha, and superior nasal concha are distinct from each other.

The structures of all the bones are quite different from each other. An outer casing that lies just under the skin at the top of the nasal cavity is called the nasal bone whereas the internal structure is nasal conchae.

Nasal conchae have the main function to increase the intranasal air volume that helps in warming and humidifying the air. The nasal bone is a structural bone and does not have various functions and complex anatomical structures like other facial bones.

The bone form of this bone can be seen by a nasal X-ray but it not indicates the density and internal surface shape of the bone properly. The inner wall is concave in shape and the uppermost part is relatively thicker than the bottom.

A person’s appearance can be changed significantly by the nasal bone. It depends on how broader and high this bone is. A surgical procedure called rhinoplasty can be done to change the shape or look of the nose. It is mainly used to change and provide a more pleasing silhouette to the nose.

The proceris and the nasalis muscles cover the nasal bones. We can pull our forehead (area between the eyebrows) downwards with the help of the proceris.

We use our nasalis muscles to flare our nostrils. The alar or the outer nostril is a part of the nasalis muscle or the dilator naris posterior that enables nostril dilation. The use of the transverse part of the nasalis muscle which is called the compressor naris helps is closing the nostrils while swimming underwater.

A wide range of facial expressions such as wrinkling the nose and frowning in anger use all these muscles. These muscles can be paralyzed completely by the wrong administration of botox injections by inadequately trained surgeons.

The patients than never change their facial expressions. The ethmoidal nerve is a branch of the nasociliary nerve that gets space from the inner groove of each nasal bone. The sensory anterior ethmoidal nerve innervates the skin of the sides of the nose, the septum, and the inner surface of the nasal cavity.

Nasal Bone Fracture

Due to contact sports, motor vehicle accidents, and physical assault the nasal bone can be damaged or fracture. Up to 50% of facial bone fractures affect one or both delicate bones, these fractures are common. The nasal bone fractures have their own category- ICD-10 Nasal Bone Fractures Diagnosis Code S02.2, provided by the International Statistical Classification of Diseases and Related Health Problems.

The bones are relatively thin and project outward thus the fractures in these bones are common. The healing of a closed nasal bone fracture takes around three weeks without any treatment. Sometimes correct surgery is required if the bones are misaligned. The process of manual realignment is used in some cases, in which a little local anesthesia is used to reset the bones by carefully manipulating them through the skin.

In the case of a degree of nasal deformity, fracture surgery or reduction surgery is required. The ENT surgeons or otorhinolaryngologists usually do not undertake surgery in swelling if any immediate breathing problem, nerve damage, continuous bleeding are not a problem.

Usually, the healing process begins after seven to ten days, when the nasal fracture is not fixed on its own, in which surgery is undertaken which needs one or both the bones to be broken again.

Nasal Bone Spur

A small projection of bone into the nasal cavity is called a nasal bone spur. Sometimes it may cause breathing problems but not every time. It depends upon its size and position. Nasal bone spurs can grow into bigger structures like the septum and slowly push it out of place, which causes a lot of pain.

To know exactly how well, you only need to pull out a nose hair. In most cases, the cartilaginous nasal septum develops into spurs. The nasal bone growth is also affected by this and causes malformation. Now the correction can be done endoscopically via the nostril that usually hides the scars.

The procedure is quite expensive. However, the reparative surgery is usually covered by medical insurance if the spur causes pain, affects breathing, abnormal nasal growth, or repositioning of other nasal structures occur.

Hypoplastic Nasal Bone

The overly small bones are called hypoplastic nasal bones. They are usually detected long before birth. The clues about certain genetic disorders can get by measuring nasal bone size during ultrasound imaging. It can undertake a more invasive amniocentesis.

The percentage of fetuses with hypoplastic nasal bone in the second trimester is very low among which 50% are Down syndrome fetuses. Therefore nasal bone hypoplasia is considered a strong morphological marker for trisomy 21.

Absent Nasal Bone

The condition is also a subcategory of the hypoplastic form of the nasal bone. The absence of nasal bone at twelfth-week gestation indicates the probability of various genetic disorders in the fetus. Similar to hypoplasia, trisomy 21 is the most common genetic disorder, but there are also high-risk factors for trisomy 18 (Edward syndrome) and trisomy 13 (Patau syndrome). Absent nasal bone can cause sometimes due to X-linked Turner syndrome.

Nasal Bone Citations
  • Etiology of Nasal Bone Fractures. J Craniofac Surg . 2017 May;28(3):785-788.
  • Nasal Bone Osteotomies with Nonpowered Tools. Clin Plast Surg . 2016 Jan;43(1):73-83.
  • Complications of Nasal Bone Fractures. J Craniofac Surg . 2017 May;28(3):803-805.
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