Question

Name the three parts of the pharynx; state whether each is an air passage only or an air and food passage. (p. 346)

Short answer

Answer: The oropharynx and laryngopharynx serve as both air and food passages.

Step-by-step solution

Identify the three parts of the pharynx

The pharynx is divided into three parts: nasopharynx, oropharynx, and laryngopharynx (also known as the hypopharynx).

Determine the function of the nasopharynx

The nasopharynx is an air passage only. It is located behind the nasal cavity and serves as a passageway for air from the nostrils to the throat.

Determine the function of the oropharynx

The oropharynx is both an air and food passage. It is located behind the oral cavity and serves as a passageway for both air from the nasal cavity and food and liquid from the mouth to the laryngopharynx.

Determine the function of the laryngopharynx

The laryngopharynx is also both an air and food passage. It is situated below the oropharynx and behind the larynx. It directs air to the lungs (through the trachea) and food to the esophagus. In summary, the three parts of the pharynx are the nasopharynx (air passage only), oropharynx (air and food passage), and laryngopharynx (air and food passage).

Key concepts

Nasopharynx

The nasopharynx is the uppermost part of the pharynx, located directly behind the nasal cavity. It acts as a dedicated air passage, channeling air from the nostrils to the throat. An important feature of the nasopharynx is the presence of the Eustachian tubes, which connect to the middle ear. These tubes help to equalize air pressure on both sides of the eardrum, essential for proper hearing.

• Location: Behind the nasal cavity.
• Function: Air passage only.
• Special Features: Contains the Eustachian tubes.

The nasopharynx also houses the adenoids, a mass of lymphatic tissue that helps to trap pathogens breathed in through the nose. By working as an air passage, the nasopharynx aids in maintaining the airflow to the lower respiratory tract while keeping unwanted particles at bay.

Oropharynx

The oropharynx is the middle section of the pharynx and is situated behind the oral cavity. It serves as a passage for both air and food. When you swallow, food and liquids move through the oropharynx on their way to the esophagus. It's a common pathway shared by the digestive and respiratory systems, which makes it crucial for directing the contents accurately to the next appropriate path.

• Location: Behind the oral cavity.
• Function: Passage for air and food.
• Connectivity: Links to both the nasopharynx and laryngopharynx.

In addition, the oropharynx contains structures such as the tonsils, which are part of the immune system, helping to guard against infections. Therefore, the oropharynx plays an integral role in facilitating the processes of breathing and digestion.

Laryngopharynx

The laryngopharynx, also known as the hypopharynx, forms the lower part of the pharynx. It sits just above the esophagus and larynx. This dual-purpose passage directs air to the trachea leading to the lungs and food and liquids to the esophagus leading to the stomach.

• Location: Below the oropharynx, behind the larynx.
• Function: Passage for both air and food.
• Integration: Channels contents to either the respiratory or digestive systems.

The laryngopharynx's strategic positioning helps to seamlessly transfer air to the windpipe and food to the esophagus without interference. This efficiency is vital for preventing aspiration, thus safeguarding the respiratory tract from food or liquid ingress.