Given a scientific question, generate a correct answer to it.

Example Input: Nonshivering thermogenesis, which involves the breakdown of brown adipose tissue, is a special methods newborns have for what purpose?
Example Output: generating heat

Example Input: What is the outer layer of an axon that acts like a layer of insulation, similar to the plastic that encases an electrical cord?
Example Output: myelin sheath

Example Input: Which nerve directly stimulates the contraction of skeletal muscles in the pharynx and larynx to contribute to the swallowing and speech functions?
Example Output:
vagus nerve