A patient presents with severe coughing after accidentally inhaling food. Imaging reveals that the food has entered the respiratory tract and lodged in a bronchus. Which bronchus is most likely affected?

A. Diaphragmatic: Diaphragmatic breathing, or abdominal breathing, primarily involves the contraction of the diaphragm, which moves the abdominal wall outward during inspiration. It is deeper and more efficient for ventilation, rather than shallow, and does not rely on rib cage movement for air intake.

B. Eupneic: Eupneic breathing refers to normal, relaxed breathing at rest. It involves both the diaphragm and intercostal muscles but is not specifically characterized by shallow or rib cage–dependent patterns; it represents regular tidal ventilation.

C. Costal: Costal breathing, also called shallow breathing, relies on the elevation and depression of the ribs to move air in and out of the lungs. This pattern is less efficient than diaphragmatic breathing and typically occurs when the rib cage shape or movement predominates, such as during rapid, shallow respirations or certain respiratory conditions.

D. Forced: Forced breathing involves active inspiration and expiration using both primary and accessory muscles to move larger volumes of air, such as during exercise or coughing. It is deep and vigorous, contrasting with the shallow nature of costal breathing.

A. Horizontal fissure: The horizontal fissure, also called the minor fissure, runs transversely across the right lung and separates the superior (upper) lobe from the middle lobe. This anatomical feature is unique to the right lung and is critical for distinguishing lobar divisions during imaging or surgical procedures.

B. Costal surface: The costal surface refers to the portion of the lung that lies adjacent to the ribs. It does not define lobar boundaries but provides contact with the thoracic cage, aiding in lung expansion and protection.

C. Oblique fissure: The oblique fissure, or major fissure, is present in both lungs and separates the superior lobe from the inferior lobe. In the right lung, it runs diagonally from the vertebral surface to the costal surface but does not divide the superior and middle lobes.

D. Apex: The apex is the superior tip of the lung extending into the thoracic inlet. It does not serve as a boundary between lobes but rather defines the uppermost portion of the lung.

E. Cardiac notch: The cardiac notch is an indentation on the medial surface of the left lung to accommodate the heart. It is absent on the right lung and therefore unrelated to right lung lobar separation.