Structure and function of the pharynx

The pharynx is a funnel-shaped channel length of 12-14 cm, facing upwards its wide end and flattened in the anteroposterior direction, is located in front of the spine. The upper wall of the pharynx adherent to the base of the skull, on the border between 6 and 7 cervical vertebra pharynx, narrowing goes into the esophagus. In the throat there is crossing of the respiratory and digestive tracts.

The cavity of the pharynx is divided into three parts: the upper - the nose (nasopharynx), a middle - the mouth (oropharynx) and the lower - guttural (hypopharynx). Front nasopharynx communicates with the nasal cavity through choanae, oropharynx communicates with the oral cavity through the pharynx, hypopharynx communicates with the bottom of the larynx. The rear wall of the pharynx is separated from the front surface of the spine layer of loose connective tissue, whereby the movable pharynx.

On the side walls of the nasopharynx is located posterior nares at the pharyngeal opening of the auditory (Eustachian) tubes which connect each side of the nasopharynx to the middle ear cavity and help maintain atmospheric pressure in it. Near the pharyngeal opening of the auditory tube is located fresh accumulation of lymphoid tissue - pipe tonsils. On the upper part and the rear wall of the nasopharynx is the pharyngeal tonsil.

Oropharynx is an extension of the nasopharynx down. From the oral cavity oropharynx delimited soft palate, palatal handles (front and rear), and the language back. The soft palate or velum, is a fold of mucous membrane, hanging freely in the cavity of the pharynx. The elongated central department of the soft palate forms a uvula. The curtain has three palatal muscles: lifting the soft palate tenses the soft palate and uvula muscle. During swallowing and pronouncing certain sounds velum is raised upwards and backwards, separating the nasopharynx from the oropharynx. Dissociation of these cavities prevents the penetration of food into the nasopharynx and provides sonority of pronunciation. When paresis and paralysis of the soft palate, the liquid food flows into the nasal cavity, as well as developing twang.

From the lateral parts of the soft palate down depart palatal arch: front (palato-lingual) and rear (velopharyngeal), attached to the first side surface of the tongue, the second - to the side wall of the pharynx. These thicker laid muscle. Between the palatal arches have a triangular-shaped indentation - tonsillar niche, there are large concentrations of lymphadenoid tissue - palatine tonsils.

The amygdala distinguish between the upper and lower poles, the outer and inner surface. On the inner surface of the tonsils, facing into the cavity of the oropharynx, there are dimples, leading to blind channels - gap, usually in the amygdala 12-20 lacunae. The magnitude of their very variable, more developed gaps in the upper pole.

Hypopharynx starts at the upper edge of the epiglottis (corresponds to the cervical vertebrae 4-6), narrowing down to a longitudinal slot and moves up into the esophagus. The front wall of the hypopharynx formed root of the tongue, it is located below the entrance to the larynx. there is a cluster of lymphoid tissue on the tongue root - lingual tonsil.

Pipe tonsils, pharyngeal, palatine and lingual tonsils form the pharyngeal lymphoid ring, which plays an important role in immune system functions.

Pharyngeal wall consists of three layers: the mucosa, fibrous membrane, muscle layer. Structure mucosa varies: in the nasopharynx it is covered with ciliated epithelium same as the nasal cavity, the remaining sections are covered with multilayer flat epithelium. The muscles of the pharynx are arranged in two directions: longitudinal (levator pharynx) and transverse (pharyngeal constrictor). When swallowing muscles raised longitudinal throat and circular cut top to bottom, thereby pushing the food towards the esophagus.

As part of the respiratory and digestive systems, pharynx performs several important functions: breathing, carrying food, voting and speech production.

When the nose breathing air from the nasal cavity gets into the throat. Condition of the soft palate has a certain significance in the implementation of respiration, because due to mobility disorders, changes in the shape or magnitude of the soft palate, it can resist airflow. The muscles of the pharynx are involved in the act of swallowing. The pharynx is involved in the formation of sound, its timbre, along with the nasal cavity and paranasal sinuses sip a sound resonator. Sound vibrations generated in the larynx, pharynx enhanced through the ability to change their size and shape. Congenital defects of the hard palate, the development of the nasal cavity and nasopharynx various pathological processes (adenoids, polyps, mucosal edema, paresis and paralysis of the soft palate) leading to pathological change in voice - nasal and distorted pronunciation of speech sounds.

The protective function is manifested in the fact that the irritation of the posterior wall of the pharynx and the root of the tongue there is a reflex cough and vomiting. The mucous membrane of the pharynx has a protective function due to the movement of the cilia of ciliated epithelium, resulting in saliva and mucus removed trapped in the cavity of the throat bacteria and dust particles, as well as due to the bactericidal properties of mucus and saliva.