Structure and functions of the nose

Distinguish between the outer nose and the nasal cavity.

The outer nose looks like a pyramid and is formed by bones, cartilages, and muscles. Outside, the nose is covered with the same skin as the face. It distinguishes: the root, the back, the tip and the wings of the nose. The root of the nose is located in the upper part of the face and is separated from the forehead by a transference. The sides of the nose along the middle line join and form the back of the nose. The back of the nose goes to the top of the nose, and the nostrils that lead to the nasal cavity are at the bottom of the nose.

The outer nose is an important part of the cosmetic ensemble of the face. The shape and size of the external nose give the facial features a unique personality.

In the nasal cavity, a forehead of the nose is distinguished, covered from the inside by the skin of the external nose, and a nasal cavity lined with a mucous membrane. The skin of the vestibule contains hairs, sweat and sebaceous glands.

The vestibule passes into the nasal cavity, which is a channel that extends longitudinally through the bones of the facial skeleton and has the shape of a prism. The bottom of the nasal cavity is the hard palate.

The nasal cavity divides into two halves: the right and left, in the septum distinguish the bone and cartilaginous parts. Behind through the choana, the nasal cavity communicates with the nasal part of the pharynx. Most of the nasal cavity is represented by nasal passages, with which the paranasal sinuses are communicated (air cavities of the bones of the skull). Three nasal shells (upper, middle and lower), located on the side walls, increase the overall surface of the nasal cavity. Between the inverted surfaces of the shells and the septum of the nose there is a slit-like common nasal passage, and under the shells there are nasal passages bearing the corresponding names: upper middle and lower. The nasolacrimal duct opens into the inferior nasal passage, the posterior cells of the latticed bone and the sphenoid sinus open in the upper nasal passage, the middle and middle cells of the latticed bone, the frontal and maxillary sinuses in the middle.

From the inside, the nasal cavity is lined with a mucous membrane, in which two distinct parts of the structure and function can be distinguished: the respiratory and olfactory parts. The respiratory part occupies the area from the bottom of the nasal cavity to the middle of the middle nasal concha. The mucous membrane of this area is covered with ciliate epithelium and contains a large number of glands secreting mucus, in addition, a submucosa base contains a variety of blood vessels.

The olfactory area occupies a part of the nasal mucosa that covers the right and left upper nasal conchas, as well as part of the middle shells and the corresponding part of the nasal septum. In the olfactory area there are nerve cells that perceive odorous substances from the inhaled air.

To the paranasal sinuses carry the airway cavities surrounding the nasal cavity and connected with it by the holes (excretory ducts). There are maxillary (gaimorovy), frontal, wedge-shaped and latticed sinuses. Their sizes vary from person to person, the largest in size is the maxillary sinus (from 5 to 30 cm3). Inside the sinuses are also lined with a mucous membrane.

The maxillary sinuses are located in the body of the upper jaw, to the right and left of the nasal cavity. The roots of the teeth of the upper jaw (3-6) in some cases can protrude into the sinus, so it may develop odontogenic inflammatory processes. The frontal sinuses are located in the frontal bone at the level of the superciliary arches on the right and left. The sinuses of the latticed bone consist of separate cells and are located in the thickness of the latticed bone. The sphenoid sinus is placed in the body of the sphenoid bone (behind the latticed bone) and is divided into two halves by a septum. By means of special apertures the sinus communicates with the nasal cavity.

The nose performs a variety of functions: respiratory, protective, resonator and olfactory.

Respiratory function is basic. The nose first perceives the inhaled air, which here is warmed, cleansed and moisturized, so the nasal breathing is the most physiological for the body.

The protective function is that the mucosal receptors react to a variety of stimuli from the external environment: chemical composition, temperature, humidity, dustiness and other air properties. When exposed to the mucous membrane of irritants, sneezing, lacrimation appears. A tear entering the nasal cavity through the nasolacrimal canal increases the secretion of the mucous glands and removes irritant substances from the nasal cavity.

The ciliary epithelium of the mucous membrane of the nasal cavity plays an important role in the mechanical removal of substances weighed in the inspired air. When the cilia oscillate, directed from the entrance to the nose to the nasopharynx, the particles moving into the nasal cavity move. Part of the larger dust particles is delayed in the area of ​​the nasal artery with hairs, and if dust particles suspended in the air still enter the nasal cavity, they are removed from it with mucus by sneezing or blowing. The protective mechanisms include also the warming and moistening of the incoming air through the nose.

Resonator function is provided by the presence of air cavities (nasal cavity, paranasal sinuses). The unequal size of these cavities contributes to the amplification of voice tones of different frequencies. Forming in the glottis, when passing through resonator cavities, the sound acquires a certain timbre (color).

Olfactory function is due to the presence of specific olfactory receptors in the nasal cavity. In human life, smells play an important role, helping to determine the good quality of food, the presence of harmful impurities in the inspired air. In a number of cases, the smell helps a person to orientate himself in the environment, to experience pleasure or disgust. The sense of smell is greatly influenced by the humidity of the air, its temperature, atmospheric pressure, the general state of man.

The nose of the newborn baby is flattened, short, the nose is narrow and low, weakly developed. With age, the back of the nose lengthens, the tip of the nose is formed. In the period of puberty, the shape of the external nose becomes constant. The paranasal sinuses in the newborns are poorly developed. By the age of 8-9 the process of formation of the maxillary sinus is over, and by 12-14 years the final form of the sinus of the frontal, latticed and sphenoid bone is taking shape.