Ear, Nose, and Throat

Anatomy and Physiology of the Nose and Throat

What is the nose?

The 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 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.