Question

The hair erector muscle is

• A. Arrector pilli
• B. Stapedius muscle
• C. Cilliary muscle
• D. Both A and B

Answer 1

The correct option is A Arrector pilli

The arrector pili muscles are some small muscles which are attached to hair follicles in mammals. Contraction of these muscles causes the hairs to stand on end, known as goose bumps.

Each arrector pili is composed of a bundle of smooth muscle fibres, attached to several follicles (a follicular unit) and is innervated by the sympathetic branch of the autonomic nervous system.

The contraction of the muscle is then involuntary and stresses, such as cold, fear etc. may stimulate the sympathetic nervous system, and thus cause contraction.

Hence the correct option is A.