Which nerve supplies the heart and lungs?

The accurate response to this question is that both the vagus nerve and the pneumogastric nerve supply the heart and lungs. The vagus nerve, also known as cranial nerve X, is a critical component of the parasympathetic nervous system, responsible for a variety of involuntary functions, including heart rate and respiratory control. It innervates the heart, regulating its rate, and provides sensory and motor functions to the lungs.

The term "pneumogastric nerve" refers to the vagus nerve, illustrating its role in both the respiratory and digestive systems. Therefore, it is effectively synonymous with the vagus nerve in this context. Because the vagus nerve and pneumogastric nerve refer to the same nerve, both indicate that this nerve is essential for controlling functions relevant to the heart and lungs.

In summary, the correct answer acknowledges the critical role of the vagus/pneumogastric nerve in innervating the heart and lungs, making both options valid.