The human nose does have bones, but its structure is complex, combining rigid bone in the upper portion with flexible cartilage in the lower two-thirds. This sophisticated framework allows the nose to be firmly anchored to the face while retaining the necessary pliability to withstand minor impacts and facilitate the functions of breathing. Understanding this dual structure is the first step in appreciating the anatomy of this prominent facial feature.
The Foundation: Bone Structure
The upper third of the external nose, known as the nasal bridge, is composed of bone. This section forms a fixed anchor point where the nose attaches to the rest of the facial skeleton. The primary structures are the two small, oblong nasal bones, which meet at the midline to create the elevated ridge. The bony framework serves as the roof of the upper nasal cavity, forming a strong, protective barrier.
These paired nasal bones articulate with several surrounding bones to establish the nose’s fixed position. Superiorly, they connect with the frontal bone of the forehead. Laterally, they join the frontal processes of the maxilla, or upper jawbone.
This rigid bony vault is responsible for the height and projection of the upper nose. Because this area is unforgiving, it is the section most commonly involved in a “broken nose” following blunt force trauma. The bone structure provides protective housing for delicate internal structures.
The Flexible Tip: Cartilage Composition
The lower two-thirds of the nose, including the tip and the sides of the nostrils, is composed almost entirely of hyaline cartilage. This material is strong enough to maintain the nose’s shape yet flexible enough to move without fracturing. This pliability allows the end of the nose to be easily compressed or manipulated.
The structure is formed by several distinct pieces of cartilage. The lateral cartilages extend downward from the bony bridge, supporting the middle portion of the nose. Below these are the greater alar cartilages, which define the shape of the nasal tip.
These greater alar cartilages form the arches of the nostrils. They are crucial for maintaining the patency of the nostrils, ensuring they do not collapse during inhalation. In addition to the main pieces, smaller accessory cartilages reinforce the structure of the nasal wings. The flexible nature of this cartilage-based portion helps dissipate force from minor impacts, making it less prone to failure than bone.
Supporting the Airway: The Internal Septum
Inside the nasal cavity, the nasal septum divides the space into two separate airways. This partition relies on a combination of bone and cartilage for support and is positioned centrally to ensure balanced airflow.
The anterior part of the septum consists of the septal cartilage, or quadrangular cartilage. This is the more flexible section of the dividing wall. Behind this cartilage, the septum transitions into a bony structure.
The main bony contributions come from two specific bones: the vomer bone, which forms the inferior and posterior part, and the perpendicular plate of the ethmoid bone, which makes up the superior part. These bones interlock with the septal cartilage and surrounding facial bones to create a stable dividing line.
If the nasal septum is not perfectly aligned, it is known as a deviated septum. This misalignment often occurs where the bone and cartilage pieces meet, causing an obstruction that can impair breathing. The septum’s precise construction is fundamental to its role in regulating air passage.
Understanding Nasal Trauma
Injuries to the nose can affect either the bony or the cartilaginous framework. A true nasal fracture involves a break in the rigid nasal bones, typically occurring at the bridge due to a strong, direct impact. This injury often results in a visibly misshapen nose and bruising around the eyes.
Damage to the flexible lower two-thirds involves the cartilage. While cartilage is resilient, severe impacts can tear the tissue or displace the pieces. One serious consequence of cartilage trauma is a septal hematoma, a collection of blood that forms beneath the lining of the septal cartilage.
If a septal hematoma is not promptly treated, the lack of blood supply can cause the cartilage to die, leading to a loss of support. This results in a characteristic deformity where the bridge of the nose collapses, sometimes called a saddle nose deformity. Trauma can also knock the septal cartilage and bone out of alignment, resulting in an acute deviated septum that blocks the airway.
The type of injury often depends on the direction and force of the blow. A frontal impact is more likely to fracture the nasal bones, while a lateral blow can cause the bony structure to fracture and the septum to buckle. Prompt medical attention is necessary for any suspected fracture or significant trauma.