Pharynx is the common passage of the respiratory system and digestive system located in the throat. It connects the mouth to the oesophagus and nose to the larynx. Food and water from the oral cavity and air from both oral and nasal cavity comes to the pharynx. Pharynx is present in vertebrates and also in invertebrates such as annelids, arthropods, etc.
Pharynx is present behind the oral and nasal cavity. It is a part of the throat and a common passage for both the digestive and respiratory system.
Pharynx opens into the oesophagus in the digestive tract and opens into the larynx in the respiratory tract.
Pharynx Structure and Parts
The pharynx can be divided into three main regions according to its location. They are:
- Nasal pharynx – As the name suggests, it is the part of the pharynx that is present posterior to the nasal cavity.
- Oral pharynx – It is the part behind the oral cavity and continues in the throat till hyoid bone.
- Laryngeal pharynx – It is the lowermost part of the pharynx from epiglottis and continues to the oesophagus.
The main features of pharynx are:
- The wall of pharynx consists of both longitudinal and circular muscles. These muscles determine the shape of the lumen.
- Isthmus connects oropharynx to nasopharynx. It is useful for breathing through the mouth and inserting food into the oesophagus through the nasal tube if required.
- Pharyngeal adenoids or tonsils are located in the wall of nasopharynx.
- Nasopharynx is lined with pseudostratified, columnar and ciliated respiratory epithelium.
- Eustachian tubes connect middle ears to pharynx. It helps in equalizing air pressure on the eardrum.
- Palatine tonsils are present in the lateral wall of the oropharynx.
- The wall of oropharynx is made up of non-keratinized, stratified squamous epithelium.
- The opening of the pharynx to the larynx is controlled by a muscular flap known as epiglottis. It is present over the larynx opening and prevents food from entering the trachea.
- The wall of laryngopharynx consists of stratified squamous epithelium.
- Laryngopharynx regulates the movement of air to lungs and food to oesophagus.
- Pharyngeal, tubal, palatine and lingual tonsils present in different parts of the pharynx are called Waldeyer’s ring. These are lymphoid tissues present in the nasopharynx and oropharynx. It provides defence against invasion of microorganisms in the digestive and respiratory tract.
Pharynx performs a dual function. It allows passage for both air and food. The main functions of the pharynx are:
- It makes air warm and humidifies it before reaching the lungs.
- It helps in the movement of food to the oesophagus. Circular muscles help in pushing the food down and longitudinal muscles help in swallowing the food by lifting and widening the walls.
- Pharynx also helps in speech, it amplifies the sound produced by the larynx or soundbox.
- Lymphoid tissues present in the pharynx are the first line of defence against foreign pathogens.
Some of the diseases associated with the pharynx are:
- Pharyngitis- inflammation of the pharynx
- Tonsillitis- inflammation of tonsils
- Pharyngeal cancer
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Frequently Asked Questions
What is the location and function of the pharynx?
Pharynx is located in the throat. It is the common passage of the respiratory system and the digestive system. It connects the mouth and nose to the oesophagus and larynx respectively. The main function of the pharynx as a part of the respiratory system is to humidify the air and as a part of the digestive system, it helps in the movement and swallowing of food to the oesophagus.
Where does the pharynx start and end?
Pharynx is the muscular hollow tube connecting the oral and nasal cavity to the oesophagus and larynx respectively. It is a five-inch long tube and starts from the base of the skull to the cricoid cartilage, which forms the dorsal part of the larynx at C6 vertebrae.
What are the 3 parts of pharynx?
The three main parts of the pharynx are:
- Nasal pharynx – present posterior to the nasal cavity.
- Oral pharynx – extends from the oral cavity till hyoid bone in the throat.
- Laryngeal pharynx – present from epiglottis to the oesophagus.
What is the difference between pharynx and larynx?
Pharynx is the common passage of respiratory and digestive tracts, which opens into larynx and oesophagus respectively. It provides the passage for food, water and air. Whereas larynx is the soundbox and is associated with the respiratory system. It is present above the trachea and prevents food from entering the trachea and produces sound due to the presence of vocal cords.
What comes first larynx or pharynx?
Pharynx comes first, which opens into the larynx.
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