Which nucleus is involved in parasympathetic innervation of the heart?

The nucleus involved in parasympathetic innervation of the heart is the nucleus ambiguus. This nucleus, located in the medulla oblongata of the brainstem, plays a crucial role in the parasympathetic control of vital functions, including heart rate. It contains the cell bodies of preganglionic parasympathetic fibers that travel via the vagus nerve (cranial nerve X) to the heart.

The vagus nerve projects to various cardiac structures, including the sinoatrial node and atrioventricular node, facilitating the modulation of heart rate. By releasing acetylcholine at these sites, the nucleus ambiguus contributes to a decrease in heart rate, which is a hallmark of the parasympathetic response.

Understanding the role of the nucleus ambiguus in parasympathetic heart innervation highlights its importance in maintaining cardiovascular homeostasis and responding to physiological changes.