Pharynx

The pharynx, commonly known as the throat, is a funnel-shaped muscular tube about 13 cm long that starts at the base of the skull and extends downwards to behind the larynx (voice box), approximately the level of the sixth cervical vertebra. It performs both the functions of the digestive and respiratory systems. Pharynx is present in invertebrates such as arthropods, annelids, etc and in vertebrates. Air from the nasal and oral cavity and food and water from the oral cavity come to the pharynx.

1.0Pharynx location

The term "Pharyngeal" relates to the pharynx. The pharynx lies behind the oral and nasal cavity and above the esophagus and the larynx.

Above: Starts at the base of the skull, just behind the nose and mouth.

Below: Extends downwards to behind the voice box (larynx), where it becomes the esophagus.

Anteriorly (in front): It is bordered by the back of the nose (nasopharynx), the back of the mouth (oropharynx), and the larynx (laryngopharynx).

Posteriorly (behind): Adjacent to the muscle of the neck and the cervical vertebrae.

2.0Anatomy of pharynx

The pharynx is divided into three central regions, from superior to inferior.

• Nasopharynx: It is a superior portion of the pharynx, lies posterior to the nasal cavity, and extends from the skull's base to the soft palate. It has an opening of the internal nostril.
• Oropharynx: Lies behind the oral cavity and continues in the throat till the hyoid bone. It has only one opening of the oral cavity (mouth).
• Laryngopharynx: It starts at the level of the hyoid bone; its inferior end opens into the esophagus, which is located posterior to the larynx. It serves as a pathway for air and food, guiding food into the esophagus and air into the larynx.

3.0Pharynx structure and parts

Histology

4.0Pharynx structure and parts (Diagram)

5.0Function of pharynx

• Vocalization: It helps in the production and amplification of sound for speech.
• Immune system: The lymphoid tissue plays a role in the body's immune response [first line of defense].
• Digestive system: It helps in swallowing and moving food from the mouth to the esophagus.

Circular muscles push the food downward, and longitudinal muscles help deglutition (swallowing) by widening and lifting the walls.

• Respiratory system: Humidity of the air and serves as a passageway for air from the nasal cavity to the larynx.

6.0Pharynx disorder

• Pharyngeal cancer:  Cancer that forms in the pharynx. 

Symptoms: Difficulty in swallowing, sore throat, and voice changes.

• Gastroesophageal reflux disease (GERD) 

It primarily affects the esophagus but can cause acid reflux into the pharynx.

Symptoms: Heartburn, sore throat, hoarseness etc.

• Laryngopharyngeal reflux (LPR)

LPR involves the flow of HCl (stomach acid) and enzymes into the pharynx and larynx.

Symptoms: Chronic cough, sensation of a lump in the throat.

• Pharyngitis: 

Painful inflammation of the throat and pharynx.

Symptoms: Sore throat, Dry and scratchy throat.

• Tonsillitis: Inflammation of tonsils can be caused by both viral and bacterial infections.

Symptoms: Swollen tonsils, fever, swollen lymph nodes.