Z line
(redirected from Z band)Also found in: Thesaurus, Medical, Financial, Encyclopedia.
Z line
n.
Any of the dark thin protein bands to which actin filaments are attached in a striated muscle fiber and that mark the boundaries of adjoining contractile units.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.