Anatomy
Summary
The pharynx is a passageway for both food and air. It is composed of muscles controlled primarily by the vagus nerve (cranial nerve X), except for the stylopharyngeus, which is innervated by cranial nerve IX. The pharynx is divided into three sections: the nasopharynx, the oropharynx, and the laryngopharynx or hypopharynx.
The nasopharynx is the first part of the airway through which typically only air passes. It is located behind the nasal cavity and paranasal sinuses, and it connects to the middle ear via the eustachian tubes, which are opened and closed by the levator veli palatini and the tensor veli palatini muscles. The nasopharynx also contains the adenoids. The next part of the pharynx is the oropharynx, located posterior to the oral cavity, which together act as the first part of the gastrointestinal tract. Consequently, both food and air pass through the oropharynx. Finally, the laryngopharynx or hypopharynx is situated posterior to the larynx. It is the most inferior portion of the pharynx, and it passes swallowed food into the esophagus.
Lesson Outline
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FAQs
The pharynx serves as a pathway for the movement of food from the mouth to the esophagus, and for air from the nose and mouth to the larynx. To facilitate this, the pharynx has critical functions, including related to swallowing and air movement.
Swallowing is a complex process, which involves coordinated movements of muscles in the oral cavity, pharynx, and larynx to move food from the oral cavity into the esophagus and prevent it from blocking the airway. Both voluntary and reflexive movements are involved. For example, the levator veli palatini elevates the soft palate to prevent food from entering the nasopharynx.
The vagus nerve, also known as cranial nerve X, provides sensory and motor functions to the pharynx, larynx, and soft palate. It helps control muscular contraction during swallowing and speaking.
The nasopharynx, oropharynx, and laryngopharynx refer to different sections of the pharynx. The nasopharynx is the uppermost part, connected to the nasal cavities. The oropharynx lies below the nasopharynx and behind the oral cavity. It receives both air from the nasopharynx and air, food, and drink from the mouth. The laryngopharynx is the most inferior portion, located posterior to the larynx. It directs food and drink into the esophagus and air into the larynx.
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