Nose: Structure, Diagram, and Functions

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:

1. Apex (Tip): The visible lower end of the nose.

2. Bridge (Root): The narrow, upper bony area between the eyes.

3. Dorsum: The ridge running from the bridge to the apex.

4. Nostrils (Nares): Two openings at the lower end of the nose that allow air in and out.

5. 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

1. Vestibule: The small front portion just inside the nostrils. It is lined with skin, hair (vibrissae), and sebaceous glands.

2. 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

1. Respiration: The nose function in the respiratory system includes filtering, warming, and humidifying the inhaled air.

2. Olfaction (Smell): The olfactory receptors detect odour molecules, helping us identify different smells (the function of the nose as a sense organ).

3. Protection: Hair and mucus trap dust and microbes, preventing them from entering deeper areas of the respiratory tract.

4. Voice Resonance: The nasal cavity adds quality to our voice, influencing how we sound.

5. 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

• Human Respiratory System

• Difference Between Bone and Cartilage