The (external) nose is the beginning of the respiratory system in humans. It is located in the center of the front of the face. It is pyramid shaped, with the base facing inferiorly. The base consists of two openings called the nares or nostrils.
These open into a pair of vestibules, one on each side. The nares are guarded by stiff nasal hairs. These nasal hairs serve to remove the larger particles (such as lint and cinders) from the inflowing air.
FAQ Nasal Septum:
The vestibules of the nose are continuous posteriorly with the right and left nasal chambers. Like the vestibules, the nasal chambers are separated by a nasal septum, a vertical wall from front to back. Constructed of bone and cartilage, the nasal septum extends from the floor to the roof and from front to back.
FAQ Mucoperiosteal Lining:
Each nasal chamber is lined with a mucoperiosteal lining. This mucoperiosteal lining is a special combination of tissues, which are rich in blood vessels. This excellent supply of blood furnishes moisture and heat.
On the surface of the mucoperiosteum are minute hair-like processes called cilia. The cilia continuously drive fluids on the surface to the rear. A part of the fluids secreted on the surface is a mucous material. As a part of the continuous process of cleansing the inflowing air, finer particles are trapped by the mucus.
Thus, the conditioning of the inflowing air depends upon direct contact with the mucoperiosteum. The greater the surface area, the more efficient will be the conditioning. The conchae are three shelf-like projections that extend from the lateral wall of each nasal chamber.
Thus, a superior, a middle, and an inferior concha are found on each side. During ordinary breathing, the air enters the vestibules of the nose and passes through the lower portions of the nasal chambers in direct contact with the inferior and middle conchae.
FAQ Olfactory Epithelium:
As the air passes through the nasal chambers, some of the air reaches the superior recesses of the nasal chambers. In these superior recesses is found the olfactory epithelium. The olfactory epithelium contains special hair cells that can detect individual molecules found in the air. Thus, the sense of smell, tests the quality of inflowing air.
FAQ Paranasal Sinuses:
Connected with each nasal chamber are cavities found in the middle layer of various skull bones. These cavities are the paranasal sinuses. Like the nasal chambers, they are lined with a continuation of the mucoperiosteum. Each paranasal sinus is named according to the bone in which it is located. The function of the paranasal sinuses is unknown.