Which cranial nerve is associated with parasympathetic control of the heart?

The vagal nerve, also known as cranial nerve X, plays a crucial role in the parasympathetic control of the heart. It extends from the brainstem and innervates various organs, including the heart. The stimulation of the vagus nerve decreases heart rate by releasing acetylcholine, which acts on the pacemaker cells in the heart. This action helps to balance the sympathetic nervous system's influence, which typically increases heart rate and contractility during stress or physical activity.

The vagus nerve is vital for maintaining homeostasis within the cardiovascular system, particularly during resting states or periods of relaxation, by promoting a reduction in heart rate and enhancing digestive processes. Understanding the role of the vagus nerve in this context aids in recognizing its importance in overall cardiovascular health and function.