Pharynx (Throat) Anatomy and Pharyngitis (Inflamed Throat)

The pharynx is commonly referred to as the throat. It constitutes the upper part of the respiratory and digestive tract that acts as a passage for the movement of food and air into the esophagus (food pipe) and the larynx (voice box), respectively. The pharynx begins at the back of the nose and the mouth, and ends in the esophagus.

Parts of the Throat

Three main cavities reside alongside the pharynx, and contribute to its functions. These three cavities are:

  • Nasopharynx: The nasal cavities extend into the nasopharynx. The nasopharynx provides a passage for the flow of air during the breathing process. The air moves downwards during inhalation and upwards during exhalation.
  • Oropharynx: The back of the mouth continues into the oropharynx. The oropharynx provides a passage for the movement of food and beverages into the esophagus.
  • Laryngopharynx: The laryngopharynx is the lowest part of the pharynx that lies behind the voice box. Both food and air pass through the laryngopharynx. The food passes into the esophagus, whereas the air passes into the larynx.

The pharynx also contains a collection of lymphoid tissue known as the tonsils. The tonsils are classified into the following categories based on their location:

  • Pharyngeal tonsil: Pharyngeal tonsil is located on the back wall of the nasopharynx. When inflamed, the pharyngeal tonsil is also referred to as the “adenoids”.
  • Tubal tonsil: The tubal tonsil is located near the opening of the Eustachian tube in the nasopharynx.
  • Palatine tonsils: Palatine tonsils lie within the oropharynx. They are located between the palatine arches on either side of the oropharynx.
  • Lingual tonsils: Lingual tonsils are located on the tongue.

These four groups of tonsils are arranged in the form of a ring, which is referred to as the pharyngeal lymphatic ring or the Waldeyer’s ring. The tonsils are composed of lymphoid tissue and perform immune functions.

Functions of the Pharynx

The pharynx plays an important role in the following processes:

Swallowing

Swallowing food and beverages is a complex process that requires the coordinated action of many different muscles. The swallowing reflex that pushes the food or drink down the esophagus is triggered when the food or fluid enters the pharynx.

Swallowing disorders (technically referred to as dysphagia) can be caused by various factors such as dry food, dry mucus membrane, neurological disorders, pharyngeal wall disorders and psychological problems. Apart from having a role in initiating the swallowing reflex, the pharynx also plays a role in triggering the vomiting reflex. Touching the back wall of the pharynx can trigger the vomiting reflex.

Breathing

The pharynx acts as a common passage for both food and air. The air from the nose and mouth enters the pharynx and is channeled into the larynx. Problems within the pharynx such as inflammation of the tonsils, stuck food, and swelling caused by allergic reactions can impede the normal breathing process.

Speech

The formation of speech sounds requires the concerted action of larynx, pharynx, soft palate and tongue.

Ear Pressure

The middle ears on both sides are connected to the pharynx through the Eustachian tubes. This connection helps in equilibration of the pressure differences between the middle ear and the throat that might be caused by changes in altitude or middle ear disorders.

Immunity

The tonsils in the pharynx help in the immune surveillance of the food and the air that enter the body through the mouth and the nose.

Pharyngitis

The pharynx can be affected by a variety of different disorders that can compromise its normal functioning. Some common examples include sore throat, itching, dysphagia, swollen tonsils, aerophagia, postnasal drip, throat injuries and throat cancer. One of the common throat disorders that affects every person at some point in life is pharynigitis. It occurs for a number of different reasons.

Pharyngitis refers to an inflammation of the pharynx. It is also commonly referred to as sore throat. The inflammation may affect any part of the pharynx, including the oropharynx, nasopharynx, and the laryngopharynx. The leading cause of pharyngitis is infection with a pathogen. However, pharyngitis can also have non-infectious causes (such as gastroesophageal reflux disorder or GERD).

Read more on sore throat.

Symptoms of Pharyngitis

Inflammation of the pharynx results in increased blood flow to the affected area, resulting in congestion and swelling inside the throat. The tonsils may or may not be involved in pharyngitis. The typical signs and symptoms of pharyngitis include discomfort or pain in the throat (especially during the act of swallowing), hoarseness of voice, and redness in the throat. Fever may be present in some cases. Hoarseness of voice is caused by inflammation of the larynx (technically referred to as laryngitis). When severe, laryngitis may cause a temporary loss of voice.

Causes of Pharyngitis

Pharyngitis can have both infectious and noninfectious causes. The following are some of the common causes of a sore throat:

  • Infections: Infections caused by a variety of viruses, bacteria and fungi can result in pharyngitis. Viral infections are the most common causes of a sore throat. Examples of viral causes of pharyngitis include flu, common cold, respiratory syncytial virus, Epstein-Barr virus, Herpes simplex virus, cytomegalovirus and HIV. Bacterial causes of pharyngitis include group A Streptococci, Streptococcus pneumoniae, Staphylococcus aureus, Corynebacterium diphtheriae, and Haemophilus influenzae type b. Fungal infections of the pharynx are usually seen in immunocompromised people (such as HIV infected patients). Candida spp. is the most common fungal cause of pharyngitis.
  • Acid reflux: Reflux of gastric acid into the esophagus and the pharynx is a common cause of sore throat. Gastroesophageal reflux disease is now being linked to many cases of morning sore throat that usually eases as the day progresses. Acid reflux to the level of the pharynx is enhanced when a person is lying down. Excessive alcohol consumption also increases the chances of acute reflux pharyngitis.
  • Smoke: Exposure to smoke, air pollutants and toxic gases can cause pharyngitis. Cigarette smoke is a common cause of pharyngitis, even in non-smokers.
  • Allergies: Allergic reactions in the upper airways can cause post-nasal drip and throat irritation. These allergic reactions can either be seasonal or perennial. Severe and life-threatening anaphylactic reactions can occur upon consumption of allergens such as mushrooms and shellfish. Emergency medical attention must be sought in such cases.
  • Foreign bodies: Sore throat may also be caused by the lodging of some foreign body in the throat or the tonsils. Small fish bones are a common example of foreign bodies that get stuck in the throat. Children may also ingest large objects that get stuck in the throat and cause pharyngitis and other problems.
  • Injury: Any injury to the pharynx can also cause sore throat. Throat injuries can occur due to foreign objects, vomiting, gastric acid reflux, shouting and excessive talking.
  • Mouth breathing: Breathing through the mouth causes the throat to become dry. This can lead to throat irritation and pain. Nasal congestion is a common cause of mouth breathing.
  • Snoring: Snoring can also cause throat irritation and pharyngitis. Pharyngitis due to snoring is usually observed upon waking up in the morning. The throat irritation eases as the day progresses. Due to this feature, snoring-induced pharyngitis may sometimes be confused with reflux pharyngitis.
  • Growths: Growths that can result in pharyngitis include peritonsillar abscess, laryngeal nodules and throat cancers.

Irrespective of the cause of the sore throat, one should seek immediate medical attention if a sore throat is accompanied by serious symptoms such as a bloody sputum or a bloody cough.

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