Opening and closing of upper respiratory tract

The muscles that make up the pharynx include pharyngeal dilators and pharyngeal constrictors. There are three main types of muscles that are directly related to the opening and closing of the upper airway:

(1) muscles that affect the position of hyoid bone, such as geniohyoid muscle and sternohyoid muscle;

(2) Tongue muscles, such as genioglossus muscles;

(3) Muscles related to soft palate activity, such as tensor veli palatini and levator veli palatini.

Some contract violently when inhaling, such as genioglossus muscle, which is called muscle that moves in phase when inhaling; Tensor palatini, on the other hand, has little to do with the respiratory cycle, and maintains a certain tense activity during the whole breathing process, which is called tense activity muscle. These muscles belong to respiratory auxiliary muscles, and their activities are an important force to keep the upper respiratory tract unblocked. They are mainly controlled by nerve impulses from three aspects:

(1) The respiratory center is driven from the brain stem area;

(2) Non-respiratory drive from brain stem area and beyond, such as random nerve impulse from cerebral cortex, can keep the coordination of upper airway muscle function when talking and singing. Awakening stimulation is responsible for the "monitoring function" of the upper airway, which plays an important role in ensuring the tension of the upper airway muscles and maintaining the opening of the upper airway.

(3) Reflex regulation, such as pressure reflex and airflow reflex of nasal cavity and pharynx mucosa; Pulmonary dilatory reflex originating from lower respiratory system; Cardiovascular reflex can affect the activity of pharyngeal muscles and change the caliber of upper airway.