rhombencephalic isthmus

[ rŏm′bĕn-sə-fălĭk ]

n.

A narrow portion in the embryonic neural tube delineating the mesencephalon from the rhombencephalon.
The anterior portion of the rhombencephalon that connects with the mesencephalon.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.