Pharynx Anatomy Introduction

The pharynx located in the throat connects the nasal cavity and mouth to the oesophagus and larynx. It serves as a common pathway for both the respiratory and digestive systems and is around 12-14cm long. It extends from the posterior aspect of the nares, running behind the mouth and the larynx to the 6^th cervical vertebra (C6) where it becomes the oesophagus.

Pharynx Position

Superior – Base of the skull

Inferior – Continuous with the oesophagus  

Anterior – Incomplete (openings of nose, mouth, and larynx)

Posterior – The cervical vertebrae

Pharynx Regions

The nasopharynx is the uppermost part of the pharynx, located behind the nasal cavity and above the soft palate. It serves primarily as an air passage and is responsible for conducting air from the nasal cavity to the lower parts of the respiratory system, such as the larynx and trachea.

On the lateral walls of the nasopharynx, two openings go to the auditory tubes. Posterior to the nasopharynx are pharyngeal tonsils (adenoids). After 7 years old, adenoids gradually undergo atrophy.

The oropharynx is the middle part of the pharynx, situated behind the mouth and extending from the soft palate to the level of the 3^rd cervical vertebra (C3). The lateral walls of the pharynx combine with the soft palate to form folds on each side.

Between each fold, lymphoid tissue called palatine tonsils are present. During swallowing, the uvula and soft palate are pushed upwards, sealing off the nasal cavity.

The laryngopharynx is the lower part of the pharynx, located below the oropharynx and extending from the hyoid bone to the oesophagus. Anterior to the laryngopharynx is the larynx.

Pharynx Structure

The pharynx is made up of several type of tissue.

Mucous Membrane: The lining of the pharynx consists primarily of mucous membrane, which is a type of epithelial tissue. This membrane is moist and contains mucus-producing cells that help lubricate the passage of food and air, as well as protect the underlying tissues from damage.

Muscular Tissue: The pharynx contains layers of smooth muscle tissue, which are responsible for the movement and propulsion of food and liquids during swallowing. The muscles of the pharynx contract in a coordinated manner to push the bolus (mass of chewed food) downward toward the oesophagus.

Lymphoid Tissue: Lymphoid tissue, which is part of the immune system, is found in various regions of the pharynx. For example, the adenoids (pharyngeal tonsils) are collections of lymphoid tissue located in the nasopharynx, while the palatine tonsils are found in the oropharynx. These tissues help to defend the body against infections by trapping and destroying pathogens that enter the respiratory and digestive systems.

Connective Tissue: Connective tissue provides structural support and organization within the pharynx. It forms the framework that supports the mucous membrane and muscle layers, helping to maintain the shape and integrity of the pharyngeal walls.

Overview Of Pharynx Structure

Below shows interactive images of the pharynx structure. Why not test your knowledge by labelling each part of the larynx before viewing the answer?

To view the interactive structure of the Pharynx head over to this page on a tablet or PC!

Function Of The Pharynx

Swallowing: One of the primary functions of the pharynx is to facilitate the swallowing process. During swallowing, food or liquid is moved from the mouth into the pharynx. Muscular contractions in the pharynx propel the bolus (the mass of chewed food or liquid) downward toward the oesophagus while simultaneously closing off the airway to prevent aspiration.

Respiration: The pharynx provides a passageway for air to travel from the nasal cavity or mouth to the larynx and trachea, facilitating breathing. It plays a crucial role in inhalation and exhalation by allowing air to pass freely through its chambers.

Vocalisation (Speech Production): The pharynx serves as a resonating chamber for speech production. By manipulating its muscles and structures, the pharynx helps modify the airflow from the respiratory system, contributing to the production of different sounds and speech articulation.

Immune Defence: The pharynx contains lymphoid tissue, such as the tonsils, which are part of the immune system. These tissues help to defend the body against infections by trapping and destroying pathogens that enter the respiratory and digestive systems.

Equalisation of Middle Ear Pressure: The pharynx contains the openings of the Eustachian tubes, which connect the nasopharynx to the middle ear. These tubes help equalize pressure between the middle ear and the atmosphere, contributing to normal hearing and balance.

Pharynx Blood Supply

Blood is supplied via several branches of facial arteries with the venous return into facial and internal jugular veins.

Conclusion

The larynx, also known as the voice box, is a vital organ located in the throat responsible for producing sound, protecting the airway during swallowing, and facilitating breathing.

Key Points

Bibliography

Larynx Anatomy: Gross Anatomy, Functional Anatomy of the Larynx, Laryngeal Tissue. (2021). EMedicine. https://emedicine.medscape.com/article/1949369-overview?form=fpf

Suárez-Quintanilla, J., Alejandro Fernández Cabrera, & Sandeep Sharma. (2020, May 12). Anatomy, Head and Neck, Larynx. Nih.gov; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK538202