Which nerve predominantly controls vital signs?

• A. Accessory nerve
• B. Vagus nerve
• C. Glossopharyngeal nerve
• D. Hypoglossal nerve

Answer: (B)

Autonomic control of vital signs hinges on the parasympathetic input to the heart, which sets how fast the heart beats. The vagus nerve provides the main parasympathetic pathways to the heart, delivering signals that slow heart rate and slow conduction through the SA and AV nodes. This direct influence on heart rate (and, by reflex pathways, on blood pressure) makes the vagus nerve the primary nerve involved in regulating these vital signs. The other nerves listed are mainly somatic motor (accessory and hypoglossal) or have only secondary autonomic roles (glossopharyngeal) that do not establish the heart’s rate as the principal driver of vital signs.