What does the vagus nerve primarily affect?

The vagus nerve plays a vital role in autonomic nervous system functions, specifically by influencing digestive and heart functions. It is the longest cranial nerve and extends from the brainstem through the neck and into the chest and abdomen, where it innervates various organs.

In terms of digestive function, the vagus nerve helps regulate gastric motility and secretion, ensuring that food is properly digested and nutrient absorption is optimized. It stimulates the production of digestive enzymes and promotes the movement of food through the gastrointestinal tract.

Regarding heart functions, the vagus nerve contributes to lowering heart rate and promoting a state of relaxation in the body. It is involved in the parasympathetic response, acting in opposition to the sympathetic nervous system, which increases heart rate and energy expenditure during stress.

While the other options highlight functions of different areas of the nervous system or different cranial nerves, they do not pertain to the primary functions of the vagus nerve, which focuses on regulating critical aspects of digestion and cardiac activity.