erector muscle of hair

n.
  1. Any of the bundles of smooth muscle fibers, attached to the deep part of hair follicles, passing outward alongside the sebaceous glands to the papillary layer of the corium, whose action erects hairs.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.