hemal arch

n.
  1. Any of three or four V-shaped bones located ventral to the bodies of the third to sixth coccygeal vertebrae and usually enclosing the ventral caudal artery and vein.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.