The nasal bones are two small oblong

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

s, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the

face The face is the front of the head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may affect th ...

and by their junction, form the

bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...

of the upper one third of the

nose A nose is a sensory organ and respiratory structure in vertebrates. It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the ...

. Each has two surfaces and four borders.

Structure

There is heavy variation in the structure of the nasal bones, accounting for the differences in sizes and shapes of the nose seen across different people. Angles, shapes, and configurations of both the bone and cartilage are heavily varied between individuals. Broadly, most nasal bones can be categorized as "V-shaped" or "S-shaped" but these are not

scientific Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

or medical categorizations. When viewing anatomical drawings of these bones, consider that they are unlikely to be accurate for a majority of people. The two nasal bones are joined at the midline internasal suture and make up the bridge of the nose.

Surfaces

The ''outer surface'' is concavo-convex from above downward, convex from side to side; it is covered by the

procerus The procerus muscle (or pyramidalis nasi) is a small pyramidal muscle in the glabella. It is involved in facial expressions such as frowning and those associated with attentional control, and it indirectly helps shield the eyes from bright light ...

and nasalis muscles, and perforated about its center by the nasal foramen, a small passageway for the transmission of a small

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

from the overlying soft tissues. The ''inner surface'' is concave from side to side, and is traversed from above downward, by a groove for the passage of a branch of the

nasociliary nerve The nasociliary nerve is a branch of the ophthalmic nerve (CN V1) (which is in turn a branch of the trigeminal nerve (CN V)). It is intermediate in size between the other two branches of the ophthalmic nerve, the frontal nerve and lacrimal ner ...

Articulations

The nasal articulates with four bones: two of the cranium, the frontal and

ethmoid The ethmoid bone (; from ) is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbit (anatomy), orbits. The cubical (cube-shaped) bone is lightweight due to a sp ...

, and two of the face, the opposite nasal and the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

Other animals

In primitive

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

and

tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...

s, the nasal bones are the most anterior of a set of four paired bones forming the roof of the skull, being followed in sequence by the frontals, the parietals, and the postparietals. Their form in living species is highly variable, depending on the shape of the head, but they generally form the roof of the snout or beak, running from the nostrils to a position short of the orbits. In most animals, they are generally therefore proportionally larger than in humans or great apes, because of the shortened faces of the latter.

Turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

s, unusually, lack nasal bones, with the

prefrontal bone The prefrontal bone is a bone separating the lacrimal and frontal bones in many tetrapod skulls. It first evolved in the sarcopterygian clade Rhipidistia, which includes lungfish and the Tetrapodomorpha. The prefrontal is found in most modern and ...

s of the orbit reaching all the way to the nostrils.

Additional images

Gray153.png, Lateral wall of nasal cavity, showing ethmoid bone in position. Gray155.png, Right nasal bone. Outer surface. Gray156.png, Right nasal bone. Inner surface.

References

External links

* —"Anterior view of skull." * —"Orbits and Eye: Bones" * —"The bones of the lateral nasal wall." * {{Authority control Bones of the head and neck Facial features Nose Flat bones Otorhinolaryngology