Aspirated foreign bodies often end up in which part of the respiratory system?

When a foreign body is aspirated, it typically follows the path of least resistance into the respiratory system, which is more commonly the right mainstem bronchus. This is due to the anatomical structure of the bronchial tree. The right mainstem bronchus is wider, shorter, and more vertically oriented compared to the left bronchus. Because of this anatomy, aspirated objects are more likely to enter the right mainstem bronchus rather than the left.

In the context of aspiration, the trachea acts as a passage that leads to either mainstem bronchus but does not itself harbor foreign bodies in the same manner as the bronchi. The alveoli, being the site of gas exchange, are often far removed from the point of entry for aspirated objects, making them less likely to be the location where such foreign bodies get lodged. Hence, when considering where aspirated foreign bodies most frequently end up, the right mainstem bronchus is significantly more common due to its anatomical characteristics.