Final answer:
In the midaxillary line, the pleural cavity ends at the diaphragm, as does the lung. However, the lung tissue itself typically ends just above the diaphragm, within the pleural cavity.
Step-by-step explanation:
The Midaxillary line is a line drawn vertically along the middle of the axilla, or armpit. This line helps locate various structures within the thoracic cavity. The pleural cavity, which encloses the lungs and is surrounded by the pleura, ends at the diaphragm, the flat, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity and is essential for breathing. The pleural cavities (right and left) are separated by the mediastinum.
Regarding the lungs, they are bordered by the diaphragm on their inferior surface, defining their lower limit within the thoracic cavity. The lungs are pyramid-shaped, with the tip, or apex, extending slightly higher than the end of the pleural cavity. The base of the lung, which rests on the diaphragm, is effectively the lower limit of the lung within the thoracic cavity.
The parietal pleura connects to the thoracic wall, mediastinum, and diaphragm, whereas the visceral pleura covers the lungs themselves. The space between these two layers is what constitutes the pleural cavity. In summary, for the midaxillary line, the pleural cavity and lungs end at the diaphragm, but while the pleural cavity extends to the diaphragm itself, the lung tissue typically ends just above the diaphragm.