Arrector pili muscle - wikipedia Arrector pili muscle Arrector pili muscle Base of pilosebaceous unit : An arrector pili muscle can be seen as the pink - staining band of tissue at the bottom center and bottom left of image Details Nerve Sympathetic postganglionic nerve fibers Identifiers Latin Musculus arrector pili Code TH H3. 12.00. 3.01041 TA A16. 0.00. 024 FMA 67821 Anatomical terminology ( edit on Wikidata ) The arrector pili muscles are small muscles attached to hair follicles in mammals. Contraction of these muscles causes the hairs to stand on end, known colloquially as goose bumps. Each arrector pili is composed of a bundle of smooth muscle fibres which attach 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 -- stresses such as cold, fear etc. may stimulate the sympathetic nervous system, and thus cause contraction. Contraction of the muscles has a number of different purposes. Its principal function in the majority of mammals is to provide insulation : air becomes trapped between the erect hairs, helping the animal retain heat. Erection of the porcupine 's long, thick hairs causes the animal to become more intimidating, scaring predators. Pressure exerted by the muscle may cause sebum to be forced along the hair follicle towards the surface, protecting the hair. Additional images Insertion of sebaceous glands into hair shaft Cross-section of all skin layers References Jump up ^ David H. Cormack ( 1 June 2001 ). Essential histology. Lippincott Williams & Wilkins. pp. 1 --. ISBN 978 - 0 - 7817 - 1668 - 0. Retrieved 15 May 2011. Myers, P., R. Espinosa, C.S. Parr, T. Jones, G.S. Hammond, and T.A. Dewey. 2006. The Animal Diversity Web ; http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/hair.html Burkitt, Young ; et al. ( 1993 ). Wheater 's Functional Histology : a text and colour atlas. Heath. p. 162. Skin and related structures Skin Epidermis Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Basement membrane Basal keratinocyte Lamina lucida Lamina densa Dermis Papillary Dermal papillae Reticular Subcutaneous tissue Panniculus / Pannus ( Panniculus adiposus Panniculus carnosus ) Membranous layer Loose connective tissue Superficial fascia Adnexa Skin glands Sweat glands : Apocrine sweat gland Eccrine sweat gland Sebaceous Hair Root sheath Outer root sheath Inner root sheath Henle 's layer Huxley 's layer Hair shaft Cuticle Cortex Medulla Bulb with matrix cells Hair follicle Muscle Arrector pili muscle Pilosebaceous unit Hair sebaceous gland Nail Nail matrix Nail plate Lunula Eponychium Paronychium Hyponychium Retrieved from `` https://en.wikipedia.org/w/index.php?title=Arrector_pili_muscle&oldid=797882394 '' Categories : Hair anatomy Talk About Wikipedia Deutsch Eesti Español فارسی Français Italiano Nederlands 日本 語 Polski Simple English Edit links This page was last edited on 29 August 2017, at 18 : 33. About Wikipedia

Question: what is one major function of arrector pili muscle contraction
Answer: to provide insulation