Diagram of the Human Nose
The external human nose, composed of bone and cartilage, is the most prominent feature of the face in humans. The internal human nose is a hollow structure above the roof of the mouth, divided by the septum into two nasal cavities that extend from the nostrils to the pharynx. The mucous membrane that lines the nasal cavities is covered with fine hairs known as cilia that help to filter dust and impurities from the air before it reaches the lungs; the air is also moistened as it passes over the sticky nasal membrane. In the human nose, there are three horizontal folds on the walls of the nasal cavities, called the conchae: other mammals may have more conchae. The uppermost concha is densely supplied with capillaries that warm the air passing over them to near body temperature. High in the nasal cavity is a small tract of mucous membrane containing the nerve cell endings of the olfactory nerve, which impart the sense of smell. Therefore, inflammation of the nasal mucous membranes, which commonly accompanies colds and other infections, not only obstructs breathing but also impairs the sense of smell.
Diagram of the human nose...
Anatomy and Physiology of the Nose and Throat
What is the human nose?
The human nose is the organ of smell located in the middle of the face. The internal part of the nose lies above the roof of the mouth. The human nose consists of:
- external meatus - triangular-shaped projection in the center of the face.
- external nostrils - two chambers divided by the septum.
- septum - made up primarily of cartilage and bone and covered by mucous membranes. The cartilage also gives shape and support to the outer part of the nose.
- nasal passages - passages that are lined with mucous membranes and tiny hairs (cilia) that help to filter the air.
- sinuses - four pairs of air-filled cavities, also lined with mucous membranes.
What are sinuses?
The sinuses are cavities, or air-filled pockets, near the nasal passage. As in the nasal passage, the sinuses are lined with mucous membranes. There are four different types of sinuses:
- ethmoid sinus - located inside the face, around the area of the bridge of the nose. This sinus is present at birth, and continues to grow.
- maxillary sinus - located inside the face, around the area of the cheeks. This sinus is also present at birth, and continues to grow.
- frontal sinus - located inside the face, in the area of the forehead. This sinus does not develop until around 7 years of age.
- sphenoid sinus - located deep in the face, behind the nose. This sinus does not develop until adolescence.
What is the throat?
The throat is a ring-like muscular tube that acts as the passageway for air, food, and liquid. The throat also helps in forming speech. The throat consists of:
- larynx - also known as the voice box, the larynx is a cylindrical grouping of cartilage, muscles, and soft tissue which contains the vocal cords. The vocal cords are the upper opening into the windpipe (trachea), the passageway to the lungs.
- epiglottis - a flap of soft tissue located just above the vocal cords. The epiglottis folds down over the vocal cords to prevent food and irritants from entering the lungs.
- tonsils and adenoids - made up of lymph tissue and are located at the back and the sides of the mouth. They protect against infection, but generally have little purpose beyond childhood.