Pharynx

The pharynx is a tube-shaped structure with two tissues that is located in the neck and covered with a mucous membrane; It connects the oral cavity and the nostrils with the esophagus and the larynx respectively, and both air and food pass through it, which is why it is part of the digestive system as well as the respiratory system. Both pathways are separated by the epiglottis, which acts as a valve. In humans, the pharynx measures about 13 centimeters, extending from the external base of the skull to the sixth or seventh cervical vertebra, at the level of the caudal border of the cricoid cartilage. It is located in front of the vertebral column.

Location

The pharynx is a muscular and membranous organ that extends from the base of the skull, limited by the body of the sphenoid bone, the basilar process of the occipital bone, and the petrous bone, to the entrance of the esophagus that coincides with the seventh cervical vertebra. It is supported by a muscle mass, the constrictor muscles of the pharynx, the muscles that are inserted into the styloid process (such as the styloglossus, stylopharyngeus, etc.) and the muscles that are inserted into the mastoid process, mainly the sternocleidomastoid. The pharynx is covered by a mucosa which is different depending on the area being studied:

• Nasofaringe: pseudoestratified ciliated cylindrical epithelium;
• Orofaringe: stratified squamous epithelium;
• Laringofaringe: stratified squamous epithelium.

Parts

• Nasofaringe: also called upper pharynx or rhinopharynx (or also epipharynx) when booting from the back of the nasal cavity. The roof of the pharynx located in the nasopharynx is called cavum, where are the pharyngeal tonsils or adenoids. The nasopharynx is limited in front of the coanas and nostrils and down the veil of the palate. On both sides it presents the hole that puts in contact the middle ear with the side wall of the pharynx through the Eustaquius Trompa. Behind this hole is a pharyngeal recess called Rosenmüller's fosita. On the back wall of the nasopharynx is seen the relief of the anterior arc of the atlas or first cervical vertebrae.

• Orofaringe: also called medium pharynx or bucofaringe, because the mouth or oral cavity is located in front through the isthmus of the jauces. Above is limited by the palate veil and down by the epiglotis. In the oropharynx are the pallion or angina tonsils, between the previous or glosopalatin or later pharynopalatin pillars.

• Laringofaringe: also called hypopharynx or lower pharynx. It includes the structures surrounding the larynx below the epiglotis, such as the piriform sinuses and the retrocricoid channel, to the limit with the esophagus. In the middle of the pyriform sinuses or pharyolaryngeal canals is the entrance of the larynx bound by the arithenoepiglotic folds.

Functions

• swallowing: It is the feeding step from the mouth to the esophagus.
• Breathing: Breathing is generally understood to be the physiological process indispensable for the life of organisms that consist of inspiration or inhalation and spiration (solutely simplify in aerobics and anaerobics vulgarly). The air passes to the pharynx, with this cavity also connects with the mouth, therefore it can also pass air through it, although it is not the most recommended, since it does not filter or heat the air.
• Fonation: It is the muscle work done to emit intelligible sounds, that is, for oral communication to exist. He's the biggest resonator.
• Hearing: It intervenes in the hearing, as the auditory tube is side to it and joins through the Eustaquio tube.
• Other functions of the pharynx are olfactory, salivation, mastication, taste functions, protection and continuation of the resonance chamber for the voice.

Muscles of the pharynx

• 

  the muscles of the pharynx
  Muscle tensor of the palate's veil.
• Lifting arm of the palate's veil.
• Highest constrictor of the faringe.

It inserts above the outside on the medial wing of the pterygoid process (in addition to its hook), the pterygomandibular ligament, of the alveolar process of the mandible on the posterior end of the mylohyoid line. The fibers run backwards to insert into the median raphe, also extending through its fascia into the pharyngeal tubercle of the basilar process of the occipital bone. The superior fibers arc beneath the levator veli palatini (internal peristaphyllum) and Eustachian tube. The interval between the upper limit of this muscle and the base of the skull is closed by the Pharyngeal fascia (known as the sinus of Morgagni).).

• Muscle stylepharyngeal.
• Average constrictor of the faringe.

Smaller than its predecessor. It inserts along the entire length of the greater horn and lesser horn of the hyoid bone in addition to the stylohyoid ligament. The most inferior fibers descend below the Inferior Constrictor; the middle fibers pass transversely, and the superior fibers ascend, overlapping those of the superior constrictor. Posteriorly it inserts into the posterior median fibrous raphe, mixing with the opposite muscle.

• Lower contrictor circle of the faringe.

The thickest of the 3, it inserts to the sides of the cricoid and thyroid cartilage. In the cricoid cartilage it inserts into the interval between the Cricothyroid (in front), and the articular facet for the inferior horn of the thyroid cartilage (behind). In the thyroid cartilage it inserts behind the oblique line. Posteriorly it joins medially with the muscle of the opposite side at the fibrous raphe (posterior midline of the pharynx). The inferior fibers are horizontal and continuous with the circular fibers of the Esophagus; the rest ascend, increasing in obliquity, continuing with the median constrictor.

• Crycothyroid muscle.
• Digastric muscle.
• Hyogloss muscle.
• Muscle style.
• Salpingopharyngeal muscle.
• Muscle palatopharyngeus.

Diseases of the pharynx

• Faringitis
• Amigdalitis
• Oropharynx cancer
• Cavum carcinoma
• Hypopharyngeal carcinoma
• Ronquido
• Cancer
• Acute Faringitis
• Sore throat

Phenomena in the pharynx and esophagus

• The food is propelled in the back direction to the esophagus (muscular tube of about 25 cm long).
• Deglution is the passage of food to the esophagus and through it to the stomach. It begins as a voluntary action, once directed it continues involuntarily.
• The upper part of the esophagus is a striated muscle, but the lower part is smooth.
• Both liquids and solids are propelled throughout that organ by peristalsis, this process is so efficient that you can swallow water from head down.
• Food passes through the pharynx and esophagus, in a matter of seconds, due to the contractions of the muscle walls of these organs. The gravity force is of little importance in the progression of the food bowl, as it is equally fast both horizontally and vertically (peristalsis).
• The esophagus passes through the diaphragm (separates chest cavity and abdominal cavity), and opens in the stomach that with the rest of the digestive organs, are found in the abdomen.