Role of pharynx

The pharynx (plural: pharynges) is the section of the throat located behind the mouth and nasal cavity and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in both vertebrates and invertebrates, albeit the structure varies considerably between species. The pharynx is responsible for transporting food and air to the oesophagus and larynx. 

The pharynx is a component of the digestive system and the conductor zone of the respiratory system in humans. (The conducting zone—which also includes the nose’s nostrils, the larynx, trachea, bronchi, and bronchioles—filters, heats, and moistens air before it is conducted into the lungs.)  Traditionally. In humans, the pharynx is formed by two sets of pharyngeal muscles that determine the shape of the lumen. They are arranged in a longitudinal layer on the inside and a circular layer on the outside. 

Types of pharynx 

The pharynx measures roughly 12.5 centimetres in length and is composed of three segments. The nasopharynx, oropharynx, and laryngopharynx are included in this group.

Nasopharynx

The nasopharynx, the top section of the pharynx, stretches from the base of the skull to the soft palate’s upper surface. It is located above the oral cavity and encompasses the space between the internal nares and the soft palate. The adenoids, alternatively referred to as the pharyngeal tonsils, are lymphoid tissue structures located in the nasopharynx’s posterior wall. Waldeyer’s tonsillar ring is a ring-shaped arrangement of lymphoid tissue in the nasopharynx and oropharynx. The nasopharynx is bordered by pseudostratified, columnar, and ciliated respiratory epithelium. Polyps or mucus, as well as congestion caused by an upper respiratory infection, can clog the nasopharynx. The auditory tube connects the middle ear to the pharynx and opens into the nasopharynx at the auditory tube’s pharyngeal aperture. The opening and closing of the auditory canals serves to balance the middle ear’s barometric pressure with that of the surrounding atmosphere. Torus tubarius in detail

The anterior part of the nasopharynx interacts with the nasal cavities via the choanae. On its lateral wall is the auditory tube’s pharyngeal entrance, which is somewhat triangular in shape and is limited behind by a hard protrusion called the torus tubarius or cushion, which is caused by the tube’s medial end cartilage elevating the mucous membrane. From the cartilaginous aperture, two folds emerge:

• The salpingopharyngeal fold is a vertical mucous membrane fold that extends from the inferior region of the torus and contains the salpingopharyngeus muscle.
• The salpingopalatine fold is a smaller fold located anterior to the salpingopharyngeal fold. It extends from the superior region of the torus to the palate and contains the levator veli palatini muscle. Additionally, it contains certain muscle fibres referred to as salpingopalatine muscle. The tensor veli palatini is lateral to the levator and contributes little to the fold, as its origin is deep within the cartilaginous opening.

Oropharynx

The oropharynx is located behind the oral cavity and extends from the uvula to the hyoid bone level. It opens anteriorly, through the isthmus faucium, into the mouth, while the palatine tonsil is located in its lateral wall, between the palatoglossal and palatopharyngeal arches. The anterior wall is composed of the tongue’s base and the epiglottic vallecula; the lateral wall is composed of the tonsil, tonsillar fossa, and tonsillar (faucial) pillars; and the superior wall is composed of the soft palate’s inferior surface and the uvula. Because food and air both flow via the pharynx, when food is eaten, a flap of connective tissue called the epiglottis closes across the glottis to prevent aspiration. The oropharynx is bordered by a squamous stratified epithelium that is not keratinized.

Laryngopharynx

The laryngopharynx (Latin: pars laryngea pharyngis), alternatively referred to as the hypopharynx, is the caudal portion of the pharynx; it is the section of the throat that links to the oesophagus. It is located inferior to the epiglottis and extends to the point at where the respiratory (laryngeal) and digesting (esophageal) paths divide. At that stage, the laryngopharynx and oesophagus are connected posteriorly. Food and fluids are transported to the stomach via the oesophagus; air enters the larynx anteriorly via the larynx. Food has the “right of way” during swallowing, while air passage is briefly blocked. The superior limit of the laryngopharynx corresponds roughly to the area between the fourth and sixth cervical vertebrae. It is placed at the level of the hyoid bone. Three principal areas comprise the laryngopharynx: the pyriform sinus, the postcricoid area, and the posterior pharyngeal wall. As with the oropharynx, the laryngopharynx acts as a food and air channel and is lined with a stratified squamous epithelium. The pharyngeal plexus innervates it.

The superior thyroid artery, the lingual artery, and the ascending pharyngeal artery all supply the laryngopharynx with blood. The vagus and glossopharyngeal nerves provide the predominant neural supply. Thus, laryngopharyngeal cancer can result in referred ear pain via the vagus nerve’s auricular branch, popularly known as “Arnold’s nerve.” This nerve is also responsible for the ear-cough reflex, which causes a person to cough when the ear canal is stimulated. 

What is the function of a larynx?

The larynx serves three critical tasks in the body:

• Breathing.
• Creating vocalisations.
• Keeping food and other particles out of the trachea, lungs, and remainder of the respiratory system.

Conclusion 

The pharynx is the canal in the body that connects the nasal and oral cavities to the larynx and oesophagus. Generally, it is referred to as the throat. The pharynx is a structure that is connected to both the digestive and breathing systems. For the digestive system, the muscle walls operate during the swallowing process and act as a conduit for food passage from the mouth to the oesophagus. It is a component of the respiratory system that facilitates the flow of air from the nose and mouth to the larynx during the breathing process.