What is a Nasal Cavity?
The nose is one of the most important organs of the respiratory and olfactory systems. The nasal skeleton, which is a component of the nose, contains the nasal cavity. There are different functions of the nasal cavity. It helps in warming and humidifying the air that is inspired by the nose. While absorbing the air, the nasal cavity also traps and removes different particles and pathogens.
The nasal cavity has a pivotal role to play in providing a sense of smell to the nose. It also clears and drains the lacrimal ducts and paranasal sinuses. In this article, students are going to look at the nasal cavity anatomy, its divisions, and the other components of the nasal cavity.
Nasal Cavity Anatomy
The nasal cavity proves to be a superior component of the entire respiratory tract in human beings. The extension of the nasal cavity is from the nose’s vestibule and it connects to the nasopharynx. There are three divisions in this tract. The vestibule forms the area that surrounds the entire anterior external opening and it leads to the nasal cavity. The respiratory region situated in the nasal cavity is lined with a pseudostratified epithelium. It is interspersed with some goblet cells that secrete the mucus. The olfactory region is situated at the apex in the nasal cavity. There are olfactory cells surrounding the region and these cells are filled with certain olfactory receptors.
Here is a nasal cavity diagram to provide more details on the structure and anatomy of the nasal cavity.
(Image will be uploaded soon)
Lateral Wall of Nasal Cavity
The lateral wall of the nasal chamber has two different curved bones known as the conchae. These bones are medially projecting and are inferiorly sized. The combination of the superior, as well as the middle conchae, result in the formation of the ethmoid bone. The inferior concha is a separate entity altogether. The nasal cavity also has a normal variant known as the supreme conchae.
When these conchae are properly covered with mucus, these are known as turbinates. The main function of turbinates is to augment the entire nasal cavity’s surface area so that it can help in different processes of humidifying and warming the air. The nasal conchae ensures that more air is entering the nasal chamber and hence there is more contact with the cavity walls. These conchae also tend to disrupt the laminar and fast-flowing air making it more turbulent and slower. Since the air is spending more time in the nasal cavity, it becomes more humidified.
There are four channels created by the turbinates. Out of these four, three of them are named meatus and the fourth channel is known as the sphenoethmoidal recess. The bones that constitute the lateral wall are the ethmoid bone, palatine bone’s perpendicular plate, a medial plate of the sphenoid bone, inferior concha, and the medial surfaces of maxillary and lacrimal bones.
Nasal Septum
Another important component of the nasal cavity structure is the nasal septum. The nasal septum divides the nasal cavity into two different but equal compartments. Components of bone as well as cartilage result in the formation of the nasal septum. It is also covered with squamous epithelium. Hence, it is a different portion altogether from the lateral wall in the nasal cavity.
The anterior section present in the septum has a covering of erectile tissue. The nasal septum also contributes to the creation of the lateral projections that are known as upper lateral cartilages. This portion takes the middle third place of the entire nose. The septum’s bony segment remains pneumatized and with its overexpansion, can create an obstruction for the flow of air.
The Blood Supply of Nasal Septum comes from the following Arteries:
The Sphenopalatine artery, that is a component of the maxillary artery.
Anterior and posterior ethmoidal arteries that are branches of the ophthalmic artery.
The Superior labial artery that is a branch of the facial artery provides supply to the anterior section of the nasal septum.
The greater palatine artery which is a part of the maxillary artery provides supply to the posterior section of the nasal septum.
The Nerve Supply of Nasal Septum is due to the following Innervations:
The anterior ethmoidal nerve provides the supply for the posterosuperior septum.
Several nasal branches situated in the greater palatine nerve provide supply to the posteroinferior septum.
The nasopalatine nerve which is a part of the maxillary nerve (CN V2) provides the supply to the anterior septum.
Conclusion
The nasal chamber or nasal cavity is an organ situated in the nose of a human being. With its functions of humidifying the inspired air and removing pathogens, it proves to be essential when it comes to the functioning of the respiratory as well as the olfactory system.
FAQs on Nasal Cavity
1. What is the nasal cavity and what are its main functions?
The nasal cavity is a large, air-filled space located above and behind the nose in the middle of the face. As the primary entry point for air into the respiratory system, it performs several crucial functions:
- Air Conditioning: It warms and humidifies inhaled air to protect the delicate tissues of the lower respiratory tract.
- Filtration: Hairs in the vestibule and the mucus lining trap dust, pollen, and other airborne particles.
- Sense of Smell: The olfactory region at the top of the cavity contains specialized receptors for detecting smells.
- Drainage: It helps drain mucus from the paranasal sinuses and tears from the nasolacrimal ducts.
2. What are the main anatomical divisions of the nasal cavity?
The nasal cavity is divided into three distinct regions based on its structure and function:
- Nasal Vestibule: This is the most anterior part, just inside the nostrils. It is lined with skin and coarse hairs (vibrissae) that act as a first-line filter for large particles.
- Respiratory Region: The largest part of the cavity, lined with a pseudostratified ciliated columnar epithelium rich in goblet cells. This region is responsible for warming, humidifying, and further cleaning the air.
- Olfactory Region: Located at the apex (roof) of the nasal cavity, this small, specialized area is lined with olfactory epithelium containing receptor cells essential for the sense of smell.
3. What is the nasal septum and what is its importance?
The nasal septum is the vertical wall of bone and cartilage that divides the nasal cavity into two separate, but equal, left and right compartments or fossae. Its primary importance is to ensure a streamlined, bilateral airflow. This separation allows air to flow through both passages simultaneously, maximising the surface area available for warming, humidifying, and filtering the air before it reaches the lungs.
4. What are the key structures of the lateral wall of the nasal cavity?
The lateral wall of the nasal cavity is anatomically complex and features three bony projections called nasal conchae (or turbinates). These are the superior, middle, and inferior conchae. Their primary role is to significantly increase the surface area of the nasal cavity. They also create turbulence in the inhaled air, slowing it down to allow more time for it to be warmed, humidified, and cleaned by the nasal mucosa.
5. Why is it essential for the nasal cavity to warm and humidify inhaled air?
Warming and humidifying inhaled air is a critical protective mechanism. The delicate tissues of the lungs, particularly the alveoli where gas exchange occurs, are sensitive to temperature and dryness. Cold, dry air can damage these cells, reduce lung function, and increase susceptibility to infections. By conditioning the air to match body temperature and 100% humidity, the nasal cavity ensures that the lungs receive air in an optimal state for efficient and safe gas exchange.
6. How does the olfactory region of the nasal cavity differ from the respiratory region?
The olfactory and respiratory regions differ significantly in both structure and function. The respiratory region is lined with ciliated epithelium and goblet cells designed to move mucus and trap debris, focusing on air conditioning. In contrast, the olfactory region, located superiorly, is lined with a specialized olfactory epithelium containing millions of olfactory neurons. Its sole function is to detect odorant molecules and transmit signals to the brain, creating the sense of smell.
7. How do the nasal conchae (turbinates) improve the function of the nasal cavity?
The nasal conchae, or turbinates, act as highly efficient air conditioners. Their curved, shelf-like shape disrupts the smooth, laminar flow of inhaled air, making it turbulent. This turbulence serves two key purposes:
- It slows the air down, increasing the time it spends inside the nasal cavity.
- It forces the air to come into maximum contact with the warm, moist mucus membrane covering the conchae.
This combined effect ensures that by the time air leaves the nasal cavity, it is thoroughly warmed, humidified, and filtered.
8. What is the relationship between the nasal cavity and the paranasal sinuses?
The paranasal sinuses are a group of four paired, air-filled spaces within the bones of the skull and face that surround the nasal cavity. They are connected to the nasal cavity through small openings called ostia. The sinuses are lined with the same mucous membrane as the nasal cavity and their primary functions include reducing the weight of the skull and resonating sound for speech. Mucus produced in the sinuses drains into the nasal cavity, which is why nasal inflammation (rhinitis) can often lead to sinus infections (sinusitis) when these drainage pathways become blocked.
