Final answer:
The superior laryngeal nerve, which innervates the larynx, branches off from the vagus nerve.
Step-by-step explanation:
The superior laryngeal nerve, which innervates the larynx (voice box), is a branch of the vagus nerve (cranial nerve X). The vagus nerve is known for its autonomic functions in the thoracic and superior abdominal cavities, including control of skeletal muscles in the pharynx and larynx for swallowing and speech functions. It is considered autonomic in nature but also directly stimulates the contraction of skeletal muscles in these areas.