Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

Medical Dictionary

annulus fibrosus

noun annulus fi·bro·sus \-fī-ˈbrō-səs, -fi-\

Medical Definition of annulus fibrosus

  1. :  a ring of fibrous tissue (such as that surrounding a heart valve); especially :  the outer portion of an intervertebral disk that surrounds the nucleus pulposus and is composed chiefly of layers of collagen fibers <Disks between the vertebrae have a soft center—a nucleus pulposus—and a tougher exterior, annulus fibrosus.—Matthew Sturdevant, The Hartford (Connecticut) Courant, 30 May 2010> <The nucleus pulposus can bulge out or herniate the anulus fibrosus, but the disk itself does not “slip.”—John Palo, Newsday, 21 Feb. 1990>

Variants of annulus fibrosus

also anulus fibrosus \ˈan-yə-ləs-\play

Seen and Heard

What made you want to look up annulus fibrosus? Please tell us where you read or heard it (including the quote, if possible).


tending to dismiss important matters

Get Word of the Day daily email!