Anatomy & Organs

Nasal Cavity – Structure, Function & Diseases

Nasal cavity

The nasal cavities , also called cavitas nasi , are paired and part of the respiratory tract . It thus plays an important role in breathing and also houses the olfactory mucosa , which is relevant for the olfactory process .

What is the nasal cavity?

The nose is formed by a bony framework that is supplemented by cartilage plates. The visible parts of the nose include the nostrils, the nasal septum and also the nostrils. However, the inner portion of the nose is much larger than the outer visible portion. It is formed by the nasal cavity (Cavitas nasi). The nasal cavity is bounded below by the hard palate (palatum durum), which in turn is formed by the upper jaw bone and the palatine bone .

Above and behind it is limited by the ethmoid bone of the base of the skull . The nasal cavity closes laterally with the three nasal conchae, the so-called conchae, which protrude into the nasal cavity. The turbinates increase the surface area of ​​the mucous membrane in the nose. The choanae, paired openings in the nasal cavity, form the transition from the nasal cavity to the pharynx . The paranasal sinuses open into the side passages of the nasal cavity .

The nasal cavity thus forms an almost triangular, pyramid-shaped cavity. This is divided in the middle by the partly cartilaginous, partly bony nasal septum into a right and a left half.

Anatomy & Structure

In the nasal cavity, the antechamber inside the outer nose, also called vestibulum nasi, can be distinguished from the lower nasal cavity (cavum nasi proprium). The antechamber corresponds approximately to the extension of the nostrils and is lined with stratified cornified squamous epithelium. In addition, the nasal hair and small sebaceous and sweat glands are located in the skin of the nasal vestibule .The so-called limen nasi, an arched bar, is the transition from the antechamber to the nasal cavity. The lining of the nasal cavity also changes here and there is a transition from the multilayered cornified squamous epithelium to the respiratory epithelium. The respiratory epithelium is also referred to here as the nasal mucosa. It is a skin with many small cilia that can carry foreign particles from the air we breathe towards the nose and throat. Goblet cells provide mucus production and numerous glands moisturize the mucous membrane.

This mucosal area is interrupted by a small area lined with the olfactory mucosa (pars olfactoria). The olfactory mucosa is mainly found in the upper nasal concha and measures around 1.3 cm² per side in adults. The nasal mucosa is supplied with nerves by the ophtalmic nerve and the maxillary nerve. Accordingly, blood supply occurs through the ophthalmic artery and the branches of the maxillary artery.

Function & Tasks

The nasal cavity has three main functions. On the one hand, it serves to warm, clean and humidify the breathing air. The mucous membrane of the nasal cavity is primarily responsible for this function. As already mentioned, there are cilia on the surface of the mucous membrane. These hairs move rhythmically in the direction of the nose and throat, transporting small foreign particles such as dust particles.

Goblet cells are embedded between the ciliated epithelium. These produce the slime on which the foreign particles stick. The ciliated epithelium and goblet cells also work together to humidify the air we breathe. The water vapor saturation in the nasal cavity is over 90%. In addition, a network of veins in the mucous membrane of the nasal cavity ensures that the air we breathe is heated. Depending on the temperature of the breathing air, the small vessels either expand or contract. The colder it is, the stronger the blood circulation in the venous network and the more the breathing air is heated.

The nasal cavity also fulfills an important function in the olfactory process, as it houses the olfactory organ. The olfactory cells embedded in the olfactory mucosa are the cell bodies of the olfactory nerve. This rises in many fine fibers through the ethmoid plate into the cranial fossa and passes on its information to the olfactory brain. In addition to these two tasks, the nasal cavity also fulfills a function as a resonance chamber for the voice.

Diseases

Due to the venous network in the nasal mucosa and a pronounced network of small capillaries at the transition from the nasal vestibule to the nasal cavity, the nasal mucosa is extremely well supplied with blood. Due to the small structures, the vessels are very fine and therefore also sensitive, so that even the smallest injuries can lead to nosebleeds (epistaxis).Nosebleeds can be quickly caused by dry air or nose picking. But the trigger of the bleeding is not always so harmless. When nosebleeds occur, especially in small children, one should always think of a foreign body in the nose. An increased bleeding tendency caused by malignant diseases of the blood can also cause nosebleeds. It is not uncommon for nosebleeds to be one of the first symptoms of leukemia . However, the most common disease of the nasal cavity is the common cold , also known as rhinitis in technical jargon.

Acute rhinitis is usually caused by viruses such as rhinoviruses or adenoviruses. As a result of the infection, there is an increased production of nasal secretions, the patient complains of a “runny nose”. The mucous membranes swell, making nasal breathing difficult. In addition, the nasal mucosa is red and possibly sore. If nasal breathing is permanently impaired and nasal secretion is constantly increased, this is referred to as chronic rhinitis. Chronic rhinitis often leads to chronic sinusitis .

Inflammation of the nasal cavity mucosa can also be caused by allergies. The main symptoms here are also obstructed nasal breathing and increased secretion. In addition, sneezing attacks and severe itching in the nose often occur.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.