pyramidal muscle

n.
  1. A muscle with origin from the crest of the pubis, with insertion into the lower portion of the linea alba, with nerve supply from the last thoracic nerve, and whose action makes the linea alba tense.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.