Introduction to the Nose
The nose is one of our sense organs that helps us detect different smells and also plays an important role in breathing. It is located in the face's centre and divided into two separate nasal passages by a thin wall called the nasal septum. While it might look simple from the outside, it has a sophisticated design internally that helps with various tasks such as filtering air, sensing odours, and keeping our respiratory system healthy.
Nose Structure and Function: Diagram
Below is a simplified structure of the nose diagram to help you understand its major parts. The image typically includes:
Nostrils (external openings)
Nasal septum
Lateral and alar cartilages
Nasal bones (bridge)
Nasal cavity (vestibule, conchae, olfactory area)
Opening into the nasopharynx (choanae)
External Parts of the Nose
The parts of the nose outside can be observed on the face. These include:
Apex (Tip): The visible lower end of the nose.
Bridge (Root): The narrow, upper bony area between the eyes.
Dorsum: The ridge running from the bridge to the apex.
Nostrils (Nares): Two openings at the lower end of the nose that allow air in and out.
Ala: The flared region on each side of the nostrils.
The framework of the External Nose
Bony Part (Upper One-Third): Consists of two nasal bones and extensions of the maxilla (frontal processes), forming the bridge.
Cartilaginous Part (Lower Two-Thirds): Includes lateral cartilages, major alar cartilages (U-shaped structures forming the nostril outline), and a single septal cartilage. Small, minor alar cartilages and fibrofatty tissue fill the gaps around the sides.
The skin covering the nose is thin and loosely attached over the bony and upper cartilaginous part, making it slightly mobile. However, over the apex and alae, the skin is thicker and contains sebaceous glands.
Nasal Cavities and Internal Structure
Inside, the nose is divided into two nasal cavities by the nasal septum. Each cavity connects to the outside through the nostrils and to the throat (nasopharynx) at the back via the choanae (posterior nasal apertures).
Divisions of the Nasal Cavity
Vestibule: The small front portion just inside the nostrils. It is lined with skin, hair (vibrissae), and sebaceous glands.
Nasal Cavity Proper: The larger, deeper region lined by mucous membrane.
Boundaries of the Nasal Cavity
Roof: Divided into three parts—the front portion by the nasal spine and nasal bones, the middle by the cribriform plate of the ethmoid bone, and the back by the sphenoid bone.
Floor: Composed of the hard palate (upper surface).
Medial Wall: The nasal septum.
Lateral Wall: Formed by the conchae (curved bony shelves), portions of the maxilla, the nasal bone, lacrimal bone, and cartilage.
In the upper part of each nasal cavity lies a region covered by olfactory mucosa for the sense of smell, whereas the rest is lined by respiratory mucosa, which is thicker and more vascular.
5 Functions of the Nose
Respiration: The nose function in the respiratory system includes filtering, warming, and humidifying the inhaled air.
Olfaction (Smell): The olfactory receptors detect odour molecules, helping us identify different smells (the function of the nose as a sense organ).
Protection: Hair and mucus trap dust and microbes, preventing them from entering deeper areas of the respiratory tract.
Voice Resonance: The nasal cavity adds quality to our voice, influencing how we sound.
Drainage of Sinuses and Tears: Nasal passages help drain the sinuses and the nasolacrimal duct (tears from the eyes).
Quick Quiz (with Answers)
1. Which part of the nose has hair and sebaceous glands?
A. Nasal cavity proper
B. Vestibule
C. Concha
D. Nasopharynx
Answer: B. Vestibule
2. Which cartilage forms the tip of the nose?
A. Major alar cartilage
B. Lateral cartilage
C. Septal cartilage
D. Minor alar cartilage
Answer: A. Major alar cartilage
3. Where are olfactory receptors located?
A. Lower one-third of the nasal cavity
B. Upper one-third of the nasal cavity
C. In the nasal septum only
D. In the nasopharynx
Answer: B. Upper one-third of the nasal cavity
4. What separates the two nostrils?
A. Alar cartilage
B. Nasal bone
C. Nasal septum
D. Maxilla
Answer: C. Nasal septum
Some Additional Tips
Breathing through the nose rather than the mouth helps warm and filter incoming air.
The sense of smell can decrease if the nasal passages are inflamed or blocked by mucus.
Keeping your nasal passages healthy is important for preventing infections.
Related Topics
FAQs on Nose: Structure, Diagram, and Functions
1. What are the main components of the external nose visible on the face?
The external nose consists of several key parts:
- The Root or Bridge: The upper bony part located between the eyes.
- The Dorsum: The ridge that runs from the bridge down to the tip.
- The Apex: The tip of the nose.
- The Nostrils (Nares): The two external openings that allow air to enter.
- The Alae: The flared, wing-like cartilaginous structures on either side of the nostrils.
2. What is the structural difference between the bony and cartilaginous parts of the nose?
The framework of the nose is composed of both bone and cartilage. The upper one-third is the bony part, made of the two nasal bones and parts of the maxilla, providing a rigid and fixed structure. The lower two-thirds are made of flexible cartilage, including the lateral, major alar, and septal cartilages, which give the nose its shape and mobility.
3. What are the five primary functions of the nose as per the NCERT syllabus?
The nose performs five crucial functions essential for health and sensory perception:
- Respiration: It serves as the primary pathway for air entering the respiratory system.
- Filtration and Humidification: It filters, warms, and moistens inhaled air before it reaches the lungs.
- Olfaction: It houses the receptors for the sense of smell.
- Voice Resonance: The nasal cavity acts as a resonating chamber that affects the quality of our voice.
- Drainage: It helps drain mucus from the paranasal sinuses and tears from the eyes via the nasolacrimal duct.
4. How does the internal structure of the nasal cavity prepare air for the lungs?
The internal nasal cavity conditions inhaled air in three ways. First, hairs in the vestibule called vibrissae trap large dust particles. Second, the rich blood supply in the respiratory mucosa warms the air to body temperature. Finally, the mucous membrane secretes mucus, which humidifies the air and traps smaller particles and pathogens.
5. What is the specific role of the nasal conchae (turbinates) inside the nasal cavity?
The nasal conchae are curved, bony shelves on the lateral walls of the nasal cavity. Their primary role is to increase the surface area of the cavity and to create turbulence in the inhaled air. This turbulence slows down the airflow, maximising the time air spends in the nose for effective warming, humidifying, and filtering.
6. How do we perceive different smells through the process of olfaction?
The process of smelling, or olfaction, begins when airborne odour molecules enter the nasal cavity and dissolve in the mucus covering the olfactory epithelium. These molecules then bind to specific olfactory receptors located on specialised nerve cells. This binding triggers a nerve impulse that travels directly to the brain's olfactory bulb, which processes the signal and allows us to identify the specific smell.
7. What is the key difference between the respiratory mucosa and the olfactory mucosa?
The key difference lies in their function and location. The respiratory mucosa lines the majority of the nasal cavity and is specialised for conditioning air; it is thick, vascular, and rich in mucus-producing cells. In contrast, the olfactory mucosa is a smaller, specialised area located on the roof of the nasal cavity that contains the chemoreceptors necessary for the sense of smell.
8. Why is breathing through the nose considered healthier than breathing through the mouth?
Nasal breathing is healthier because the nose is specifically designed to be a superior air-conditioning system. It effectively filters, warms, and humidifies incoming air, protecting the delicate tissues of the lungs from cold, dryness, and pathogens. Mouth breathing bypasses these critical protective functions, allowing unfiltered, cold, and dry air direct access to the lower respiratory tract, which can increase the risk of infections and irritation.
9. How do the nasal passages contribute to the resonance of our voice?
The nasal cavity functions as a resonating chamber, similar to the body of a guitar. Sound produced by the vocal cords travels up into the pharynx and nasal cavity, where it vibrates. The size and shape of these passages add unique frequencies and qualities to the sound, influencing its final tone and richness. This is why a blocked nose alters vocal sound, making it appear muffled or 'nasal'.
10. How can the structure of the nasal septum impact breathing efficiency?
The nasal septum is the wall of bone and cartilage that divides the nasal cavity into two separate passages. Ideally, it is straight, allowing for balanced airflow. However, if the septum is significantly deviated, it can obstruct one or both passages. This obstruction disrupts smooth, laminar airflow, causing turbulence and increasing resistance, which makes breathing feel more difficult and less efficient.
