Pharynx

Pharynx also known as throat, it is a single hollow and muscular tube that conducts air to the larynx and food to the esophagus . At least seven canals are counted that coincide at this point (two nostrils, the posterior connection with the mouth, the larynx, the esophagus, two Eustachian tubes).

Summary

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  • 1 What is the pharynx?
  • 2 Shape
  • 3 Location
  • 4 Functions
  • 5 Components
  • 6 muscles
  • 7 Nerves
  • 8 Blood Irrigation
  • 9 Inlet and Outlet Holes
  • 10 Structural Fabrics
  • 11 Relationship with the larynx
  • 12 Swallowing
    • 1 What happens when we swallow?
  • 13 Phenomena in the pharynx and esophagus
  • 14 Diseases related to the Pharynx
    • 1 Pharyngitis
    • 2 Nasopharyngeal Cancer
  • 15 Sources

What is the pharynx?

The pharynx is a muscle in the form of a tube that helps to breathe and is located in the neck and lined with mucous membrane; connects the nose and mouth with the larynx and esophagus respectively, and through it both air and food pass, making it part of the digestive as well as the respiratory system. In the human being it measures about thirteen centimeters, extended from the external base of the skull to the 6th or 7th cervical vertebra, located in front of the vertebral column. This cavity communicates with the nose through two holes, and also with the ear through two other ducts (Eustachian tubes). It also communicates with the respiratory tube (trachea); but at the moment of passing the food, this passage is closed by means of a valve, called the epiglottis, which prevents it from going into the respiratory tube. In the pharynx is the palate veil, which is extended laterally in two folds, which are the pillars. On the pillars are glands called tonsils, which defend the body from infection. The pharynx is covered with a mucous membrane and is about 13 cm. long which is divided into three depends on the area studied:

  • Rhinopharynx: pseudo-stratified ciliated cylindrical epithelium;
  • Mesopharynx: stratified squamous epithelium;
  • Hypopharynx: pseudo-stratified ciliated cylindrical epithelium.

Shape

It is a hollow organ, in the form of a widened cylinder or an open-front funnel whose roof corresponds to the occipital.

Location

It is located in the anterior part of the neck, above the larynx, the trachea and the esophagus. Behind the mouth (the soft palate) and below the nasal cavity. It extends from the base of the skull to the lower border of the cricoid cartilage, opposite the sixth cervical vertebra, it relates upwards with the body of the sphenoid and the basilar portion of the occipital and downwards it joins the esophagus. Since it starts from the back of the nasal cavity, its highest end is called the nasopharynx. The inferior, or oropharynx, occupies the posterior area of ​​the mouth, ending at the epiglottis.

Features

  • Swallowing: This is the passage of the food bolus from the mouth into the esophagus.
  • Breathing: Breathing is generally understood as the indispensable physiological process for the life of organisms that consists of inspiration or inhalation and expiration (it is usually simplified into ‘aerobic’ and ‘anaerobic’ vulgarly).
  • Phonation: It is the muscular work carried out to emit intelligible sounds, that is, for oral communication to exist.
  • Hearing: It intervenes in hearing since the auditory tube is lateral to it and they are united through the Eustachian tube.
  • Other functions of the pharynx are olfaction, salivation, chewing, taste functions, protection and continuation of the resonance chamber for the voice.

Components

  1. Nasopharynx

It is the back of the nasal cavity, and basically a component of the respiratory system. It communicates with the oropharynx through the pharyngeal isthmus, which is closed during swallowing to prevent food from passing into the shell. It is home to the pharyngeal tonsil , a mass of lymphoid tissue that, when inflamed, produces “adenoids.” The Eustachian tubes are attached to the walls of the nasopharynx, approximately 1 or 1.5 cm. the roof of it; They are in charge of regulating the pressure of the tympanic cavity with the outside. So when we yawn our ears are “uncovered,” just like swallowing on airplanes.

  1. Oropharynx

It extends from the soft palate to the edge of the epiglottis , communicates with the mouth through the oropharyngeal isthmus . It is characterized by being surrounded by a ring of lymphoid mass, the tonsils . They are joined by two muscles to the palate and the space between these pillars is called the tonsillar fossa. The term maw encompasses these four components.

  1. Laryngopharynx

It extends from the upper edge of the epiglottis to the lower edge of the cricoid cartilage , from where it extends into the esophagus . Ahead is the opening to the larynx.

Muscles

They are skeletal fibers in two layers, the outer layer is circular and comprises three constricting muscles; the internal one is longitudinal and includes two elevator muscles. The lower constrictor is a kind of sphincter that blocks air from entering the esophagus, but relaxes during swallowing; They also aid in the movement of the vocal cords. The middle constrictor serves as a union and protection for the shape of the pharynx. The upper constrictor aids in swallowing. All of these narrow the pharyngeal walls, forcing the food bolus to go to the stomach. The levator muscles are the palatopharynx that forms the lower pillar of the soft palate; and the stylopharynx that runs throughout the pharynx and is primarily responsible for raising the larynx when swallowing.

  • Tensor veil muscle of the palate.
  • Elevator muscle of the palate.
  • Superior constrictor muscle of the pharynx.
  • Stylopharyngeal muscle.
  • Middle constrictor muscle of the pharynx.
  • Lower contracting muscle of the pharynx.
  • Cricothyroid muscle.
  • Diastric muscle.
  • Hiose muscle.
  • Styloglossus muscle.
  • Salpingopharyngeal muscle.
  • Palatopharyngeal muscle

Nerves

Most of the pharynx is enervated by the pharyngeal plexus, formed by the pharyngeal branches of the vagus and glossopharyngeal

Blood Irrigation

The pharynx is mainly irrigated by the ascending pharyngeal and inferior thyroid arteries, branches of the external carotid and subclavian arteries, the venous plexuses are located in the posterior part, and the lymphatic system empties into deep cervical ganglia.

Inlet and Outlet Holes

In its upper part is the mouth of the nostrils (through the choanae, posterior nasal windows, and it is the seat of the pharyngeal amygdala). Its middle part communicates with the bottom of the oral cavity (through the jaws). Its lower anterior part communicates with the larynx and the posterior part extends into the esophagus. The pharynx communicates with the ear through the Eustachian tubes (next to each hole is an amygdala) in order to balance the pressures on each side of the eardrums.

Structural Fabrics

Pavement epithelium, membranous and mucous covering that covers the entire pharynx, except in the rhinopharynx. Pseudostratified cylindrical (nasopharynx), and stratified plane (buccopharynx and laryngopharynx). Fibers to prevent deformation and keep the parts together, and ribbed muscle fibers in two layers.

Relationship with the larynx

It is located directly on the larynx, communicates it with the upper airways (nostrils and mouth) and prevents food from going to it during swallowing.

Swallowing

What happens when we swallow?

Swallowing means the passage of food from the mouth to the stomach. It can be divided into three stages: the buccal, the pharyngeal and the esophageal.

  • In oral time the food bolus is formed and is completely voluntary. Once the bolus is formed, it is compressed by the tongue and cheeks against the soft palate, leaving it in an almost vertical position between the tongue and the diagonal wall that forms the soft palate and the palatopharyngeal sheets. Once this process has started, breathing stops momentarily to prevent the irregular passage of food into the airways.
  • In pharyngeal time, a series of movements occur in order to enable certain ducts (digestive) and close others (respiratory). This second time is involuntary, involuntary contractions have caused the bolus to be directed to the posterior wall, and thus prevent it from returning. This progress is associated with an elevation of the laryngeal walls and the hyoid bone. The closing of the nostrils is achieved by raising the veil of the palate. As a result of muscle contraction the larynx also rises forward. The upper hole is applied against the base of the tongue and the epiglottis finishes sealing the hole; the glottis also closes. Thus, the food is forced down the hypopharynx into the esophagus, otherwise a coughing occurs. All of these movements happen very quickly (from 0.2 to 0.3 sec.). The sphincter of the esophagus (group of circular fibers) opens when the bolus arrives. This muscle prevents air from passing into the esophagus.
  • Sphageal time transports the bolus through the esophagus into the stomach.

Pharynx and esophagus phenomena

  • The food is propelled posteriorly into the esophagus ( muscle tube about 25 cm long).
  • The swallowing is the passage of food into the esophagus and through him to the stomach . It begins as a voluntary action, once it is started 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 along that organ by peristalsis, this process is so efficient that water can be swallowed upside down.
  • Food passes through the pharynx and esophagus in seconds, due to contractions of the muscular walls of these organs. The force of gravity is of little importance in the progression of the food bolus, since it is equally fast both horizontally and vertically (peristalsis).
  • The esophagus passes through the diaphragm (separates the thoracic cavity and abdominal cavity ), and opens in the stomach, which with the rest of the digestive organs, are found in the abdomen.
  • The stomach, intestines, and other organs of the abdominal cavity are held suspended by the folds of the peritoneum known as the mesentery.

Pharynx-related diseases

Pharyngitis

Pharyngitis is an inflammation of the throat (pharynx), usually caused by a virus but also, and often, by bacteria. It can occur in viral infections such as the common cold, influenza, and infectious mononucleosis, as well as in streptococcal infections (strep throat) and some sexually transmitted diseases (gonorrhea, for example). Symptoms include sore throat and swallowing discomfort, in both viral and bacterial infections. The mucous membrane may be inflamed and covered with a white membrane or pus. Fever, swollen lymph nodes in the neck, and a high white blood cell count. Common pain relievers and throat lozenges can ease discomfort. Also gargle with warm salt water. Antibiotics should not be administered unless you are sure that it is a bacterial infection, in this case, the most used is penicillin. In some extreme cases, pharyngitis can lead to kidney infections and conditions, such as rheumatic fever or acute nephritic syndrome. Also, due to the bacteria lodged in the throat, it can be the cause of meningitis.

Nasopharyngeal cancer

Cancer in the upper part of the pharynx that occurs in children and young adults. It is rare in this hemisphere but very frequent in the East. The Epstein-Barr virus, which causes infectious mononucleosis, is involved in this type of cancer. The first symptom is a permanent obstruction of the airways or Eustachian tubes (fluid may collect in the middle ear). There may be pus or blood in the discharge from the nose, including nosebleeds. Part of the face is rarely paralyzed. Cancer can spread to the lymphatic vessels in the neck. It is detected by biopsy and is treated with radiation therapy. The survival rate is 35% after 5 years of diagnosis.

 

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