Respiratory Function
The pharynx not only serves as a conduit for airflow during respiration but also contains an abundance of glands within or beneath its mucosa. These glands contribute to the regulation of the temperature, humidity, and cleanliness of inspired air, although this function is weaker compared to that of the nasal cavity.
Speech Formation
The pharyngeal cavity acts as one of the vocal resonating chambers. During phonation, the pharyngeal and oral cavities adjust their shapes to produce resonance, making the voice clear, harmonious, and pleasing. This process is coordinated by the soft palate, mouth, tongue, lips, and teeth to form various speech sounds. A normal pharyngeal structure and appropriate adjustments in the size and shape of the pharynx during phonation play an important role in the formation and clarity of speech.
Swallowing Function
Swallowing is a reflexive, coordinated movement involving multiple groups of pharyngeal muscles. Swallowing can be divided into three stages based on the passage of food: the oral phase, the pharyngeal phase, and the esophageal phase. Once initiated, the act of swallowing cannot be voluntarily stopped. The swallowing center is located within the reticular structure of the medulla oblongata, near the vagal nucleus, and receives afferent input from cranial nerve fibers originating from the soft palate, posterior pharyngeal wall, epiglottis, and esophagus.
Protective and Defensive Function
This function is mainly achieved through the pharyngeal reflex. On one hand, a coordinated swallowing reflex can close off the nasopharynx and laryngopharynx during swallowing or vomiting, preventing food from entering the trachea or regurgitating into the nasal cavity. On the other hand, when foreign bodies or harmful substances come into contact with the pharynx, nausea and vomiting may occur, facilitating the expulsion of such substances. Normal or pathological secretions from the nasal cavity, paranasal sinuses, and lower respiratory tract can also be expelled through the pharyngeal reflex or swallowed, allowing gastric acid to neutralize microorganisms.
Regulation of Middle Ear Pressure
The opening of the pharyngeal orifice of the auditory tube is associated with pharyngeal muscle movements, particularly during swallowing. Continuous swallowing movements cause the auditory tube to open repeatedly, ensuring that the air pressure in the middle ear remains balanced with the external atmospheric pressure. This balance is a key condition for maintaining normal hearing.
Immunological Function of the Tonsils
Human tonsils, along with lymph nodes, Peyer's patches in the gastrointestinal tract, and the appendix, are all classified as peripheral immune organs. The germinal centers of the tonsils contain various phagocytic cells and can produce immune cells and antibodies, such as T cells, B cells, macrophages, and immunoglobulins. These components provide active defense against harmful substances invading the body via blood, lymph, or other tissues. At birth, the tonsils lack germinal centers, but their immune function becomes increasingly active with age. Between the ages of 3 and 5 years, frequent exposure to external allergens leads to a significant enlargement of the tonsils, which should be considered a normal physiological phenomenon. After puberty, the immune activity of the tonsils gradually diminishes, and the tonsillar tissue itself decreases in size over time.