Which of the following structures is not found in the mediastinum?

A. Quiet inspiration involves the diaphragm and external intercostal muscles without significant involvement of the neck and abdominal muscles.
B. Forceful exhalation (such as during coughing or strenuous activities) engages the abdominal muscles and sometimes the neck muscles (such as the sternocleidomastoid), as they help to push air out of the lungs by increasing intra-abdominal and intrathoracic pressure.
C. None of the answers are correct is incorrect because forceful exhalation involves these muscles.
D. Quiet exhalation primarily relies on passive recoil of the lungs and relaxation of the diaphragm, with minimal involvement of the neck or abdominal muscles.

A. Air pressure refers to the total pressure exerted by the mixture of gases in the atmosphere, but it does not refer to the pressure of each individual gas.
B. Complement pressure is not a standard term in respiratory physiology or gas laws.
C. Gas concentration pressure is not a recognized term. The pressure exerted by a gas is referred to as its partial pressure, not its concentration.
D. Partial pressure refers to the pressure exerted by an individual gas in a mixture of gases. For example, the partial pressure of oxygen (pO₂) in the blood is the pressure exerted by oxygen alone, independent of other gases like carbon dioxide or nitrogen