muscular triangle

n.
  1. The triangle bounded by the sternocleidomastoid muscle, by the superior belly of the omohyoid muscle, and by the anterior midline of the neck, and occupied by the infrahyoid muscles.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.