The nasal cartilages are structures within the nose that provide form and support to the nasal cavity. The nasal cartilages are made up of a flexible material called hyaline cartilage (packed collagen) in the distal portion of the nose. There are five individual cartilages that make up the nasal cavity: septal nasal cartilage, lateral nasal cartilage, major alar cartilage (greater alar cartilage, or cartilage of the aperture), minor alar cartilage (lesser alar cartilage, sesamoid, or accessory cartilage), and vomeronasal cartilage (Jacobson's cartilage).
The nasal cartilages associate with other cartilage structures of the nose or with bones of the facial skeleton. These associations create vent-like structures within the nose so that air can flow from the nasal cavity to the lungs or vice versa. Therefore, the nasal cartilages are structures that aid the body in respiratory functions to intake oxygen or expire carbon dioxide. Abnormalities or defects in the nasal cartilages affect airflow through the nasal cavity, resulting in respiratory issues. Surgical techniques have been produced to adjust the position or repair the nasal cartilages so that maximal airflow is once again accomplished. Some of these surgical techniques include: septoplasty (restructuring the septal nasal cartilage), upper lateral cartilage repositioning (restructuring the lateral nasal cartilage), and sliding alar cartilage (restructuring the major alar cartilage). Rhinoplasty, which is the surgical reconstruction of the nose, has increased in recent popularity for functional and social purposes. Other mammals also contain nasal cartilages in order to maintain structure and function for the nasal cavity. The orientation of the nasal cartilages can produce different shapes and sizes of the nostrils and nasal cavities. For the most part, animals contain similar cartilage structures within the nose but vary in the number of different cartilage structures they have. Donkeys, buffalo, and camels have a variety of cartilage structures that are analogous to humans but they all lack septal nasal cartilages. Instead, they have multiple components merging to form the nasal septum. Even though nasal cartilages differ between species, they all aid in the function of the respiratory system.
Structure and function
Septal nasal cartilage
The septal nasal cartilage is a flat, quadrilateral piece of hyaline cartilage that separates both nasal cavities from one another. The septal nasal cartilage fits in a place between the perpendicular plate of the ethmoid and vomer bones while also being covered by an internal mucous membrane. The superior portion of the septal nasal cartilage attaches to the nasal bones, while the inferior portion attaches to the alar cartilages via fibrous tissues. The septal nasal cartilage separates both right and left nasal cavities, which allows air to pass through them. Providing two cavities generates turbulence within the tight spaces, allowing air to flow quicker bidirectionally. The septal nasal cartilage is also the main structure that provides the orientation of the nose, being the midline structure of the organ. With an offset septal nasal cartilage, the nose will appear crooked to the viewer. A crooked nose can block airflow coming from the nares to the lungs or vice versa. This can lead to respiratory issues due to low oxygen but high carbon dioxide counts within the body. A surgical procedure to correct this issue is called septoplasty.
Lateral nasal cartilage The lateral nasal cartilage is a wing-like expansion extending out from the septal nasal cartilage. The lateral nasal cartilage lies inferiorly to the nasal bones while sitting superiorly to the major alar cartilage, separated by a narrow fissure. The lateral nasal cartilage and major alar cartilage curl up upon interaction with one another, forming a tight connection through fibrous tissues. Like the septal nasal cartilage, the lateral nasal cartilage is composed of hyaline cartilage. Hyaline cartilage provides form and flexibility within a specific structure. The superior portion of the lateral nasal cartilage fuses with the septum to provide support within the nasal cavities. With a collapse of the lateral nasal cartilage, the inner nasal valve could become obstructed and prevent the movement of airflow throughout. A new surgical technique to reposition the lateral nasal cartilage has been constructed to relieve the site of obstruction within the inner nasal valve and regain maximal airflow throughout the nose (upper lateral cartilage repositioning).
Major alar cartilage The major alar cartilages are positioned with one structure on each side of the nasal tip. Superiorly, the major alar cartilages are connected to the lateral nasal cartilage via fibrous tissues. Composed of hyaline cartilage, these structures are very thin and folded to form the lateral and medial crus. The medial crus is the inner portion of the major alar cartilages that are situated perpendicularly to the septal nasal cartilage. The lateral crus is the outer portion of the major alar cartilages that associate with the ala of the nose.
Both crus come together to form an oval tip at each nostril. Both sides of the major alar cartilages merge to form a notch at the tip, which is referred to as the apex of the nose. With the formation of the medial and lateral walls within the nares, the major alar cartilages function to hold open each naris. This allows maximal airflow to reach the nasal valve, allowing optimal respiration. Due to weakness corresponding with the lateral crus in certain individuals, a technique called sliding alar cartilage (SAC) has been a procedure practiced to restructure and support the nasal tip.
Minor alar cartilage The minor alar cartilages are 3 to 4 small hyaline cartilage pieces on both sides of the nose that sit between the lateral nasal cartilage and the major alar cartilage. Associated within the ala of the nose, these small structures are contained within the most dorsal part of the ala. Also known by its other name, "accessory cartilage", these structures aid to provide form and strength at the base of the nares in conjunction with the major alar cartilage.
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