The sheet of skeletal muscle that is active during breathing and lies along the inferior border of the thoracic cavity is the diaphragm. Here's why:
1. The diaphragm is a dome-shaped muscle located below the lungs and separates the thoracic cavity (where the heart and lungs are located) from the abdominal cavity (where the stomach, liver, and other organs are situated).
2. When you inhale, the diaphragm contracts and moves downward, creating more space in the thoracic cavity for the lungs to expand and fill with air.
3. This contraction of the diaphragm is essential for the process of breathing or respiration. When you exhale, the diaphragm relaxes and moves back up, pushing air out of the lungs.
4. The diaphragm plays a crucial role in the mechanical aspect of breathing and is considered one of the primary muscles involved in the breathing process.
Therefore, the correct answer to the question is:
OC. diaphragm
This muscle is vital for the involuntary action of breathing that keeps us alive by facilitating the exchange of oxygen and carbon dioxide in our body.
