Ranvier's node

[ränvyāz, rän-vyāz, räɴ-]
n.
  1. A short interval in the myelin sheath of a nerve fiber, occurring between every two successive segments of the myelin sheath.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.