Cranial Nerve X, also known as the vagus nerve, is one of the twelve pairs of cranial nerves. It plays a crucial role in the autonomic nervous system, primarily responsible for regulating involuntary bodily functions. This nerve extends from the brainstem to various organs, including the heart, lungs, and digestive tract. The vagus nerve is involved in several important functions, such as controlling heart rate, promoting digestion, and facilitating communication between the brain and the gut. It also contributes to the reflex actions of swallowing and coughing, making it essential for maintaining overall health and well-being.