Michigan Esthetician State Board Practice Exam

What type of nerve fibers stimulate the arrector pili muscles?

1. Sensory nerve fibers

2. Motor nerve fibers

3. Autonomic nerve fibers

4. Sympathetic nerve fibers

The correct answer is: Motor nerve fibers

The arrector pili muscles, which are small muscles attached to hair follicles, are stimulated by motor nerve fibers. These fibers are responsible for conveying signals from the central nervous system to the muscles, resulting in muscle contractions. When the arrector pili muscles contract, they cause the hair to stand up, a response often referred to as "goosebumps," which can occur due to various stimuli, including cold temperatures or strong emotions. In the context of the other options, sensory nerve fibers are primarily involved in transmitting sensory information to the brain, not in muscle contractions. Autonomic nerve fibers control involuntary bodily functions, but the specific fibers that act on the arrector pili muscles are categorized as motor fibers. While sympathetic nerve fibers can be involved in certain involuntary responses (like the fight-or-flight reaction), the direct stimulation of the arrector pili primarily results from the action of motor nerve fibers.