Definition
noun
(anatomy) A thin, white sheet of whiter matter fibers in the brain between the putamen and claustrum
Supplement
The central nervous system is made up of white matter and grey matter. The white matter is an important component of the central nervous system since it is the one relaying and coordinating different brain regions. It is associated with brain learning and dysfunctions. Although it is composed of myelin-coated axons, it is the one controlling the signals that nerve cells share between different brain regions. sup>1 The white fibers separating the claustrum and the lentiform nucleus make up the external capsule. The claustrum is a thin layer of neurons attached to the underside of the neocortex. The lentiform nucleus is the cone-shaped structure located near the internal capsule.
The external capsule is therefore a layer of white matter fibers in the central nervous system. It consists primarily of lipid and fatty tissues. It serves as a route for cholinergic fibers (from basal forebrain) to the cerebral cortex. It also joins the internal capsule around the lentiform nucleus.
See also:
- internal capsule
- claustrum
- putamen
- white matter
- brain
- cerebral cortex
- cholinergic fiber
- central nervous system
Reference(s):
1Fields, Douglas (March 2008). “White Matter”. Scientific American 298 (3): 54–61. Link
