- An arch or fold; as, the fornix, or vault, of the cranium;
the fornix, or reflection, of the conjuctiva. - Esp., two longitudinal bands of white nervous tissue
beneath the lateral ventricles of the brain.
- Nerve fibre sheath - A soft white substance constituting the medullary sheats of
nerve fibers, and composed mainly of cholesterin, lecithin, cerebrin,
albumin, and some fat. - One of a group of phosphorized principles occurring in
nerve tissue, both in the brain and nerve fibers.