Final answer:
The muscles responsible for goose bumps are the arrector pili muscles, which contract in response to cold or emotional stimuli to insulate the skin.
Step-by-step explanation:
The muscles that can cause goose bumps are called the arrector pili muscles. In response to stimuli from the sympathetic nervous system, these tiny muscles located in the dermis contract, pulling on hair follicles and causing the hairs to stand up straight.
This reaction results in the characteristic bumps known as goose bumps. It is part of the body's response to cold or emotional stimuli, as it can help to trap more air under the hairs, thereby insulating the skin and conserving body heat.