The external capsule is a series of
white matter
White matter refers to areas of the central nervous system that are mainly made up of myelinated axons, also called Nerve tract, tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distr ...
fiber tracts in the
brain
The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...
. These fibers run between the most lateral (toward the side of the head) segment of the
lentiform nucleus
The lentiform nucleus (or lentiform complex, lenticular nucleus, or lenticular complex) are the putamen (laterally) and the globus pallidus (medially), collectively. Due to their proximity, these two structures were formerly considered one, howev ...
(more specifically the
putamen
The putamen (; from Latin, meaning "nutshell") is a subcortical nucleus (neuroanatomy), nucleus with a rounded structure, in the basal ganglia nuclear group. It is located at the base of the forebrain and above the midbrain.
The putamen and c ...
) and the
claustrum
The claustrum (Latin, meaning "to close" or "to shut") is a thin sheet of neurons and supporting glial cells in the brain, that connects to the cerebral cortex and subcortical regions including the amygdala, hippocampus and thalamus. It is locate ...
.
The white matter of the external capsule contains fibers known as corticocortical
association fibers. These fibers are responsible for connecting the
cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...
to another cortical area. The capsule itself appears as a thin white sheet of white matter.
The external capsule is a route for
cholinergic fibers from the
basal forebrain to the
cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...
.
The putamen separates the external capsule from the
internal capsule
The internal capsule is a paired white matter structure, as a two-way nerve tract, tract, carrying afferent nerve fiber, ascending and efferent nerve fiber, descending axon, fibers, to and from the cerebral cortex. The internal capsule is situate ...
medially and the claustrum separates it from the
extreme capsule laterally. But the external capsule eventually joins the
internal capsule
The internal capsule is a paired white matter structure, as a two-way nerve tract, tract, carrying afferent nerve fiber, ascending and efferent nerve fiber, descending axon, fibers, to and from the cerebral cortex. The internal capsule is situate ...
around the lentiform nucleus.
Additional images
File:Gray682.png, Superficial dissection of brain-stem. Lateral view.
File:Gray689.png, Superficial dissection of brain-stem. Ventral view.
File:Gray691.png, Dissection of brain-stem. Dorsal view.
File:Slide5gg.JPG, External capsule
File:Slide7kk.JPG, External capsule
File:Slide2GRE.JPG, Ventricles of brain and basal ganglia. Superior view. Horizontal section. Deep dissection.
File:Slide3GRE.JPG, Ventricles of brain and basal ganglia.Superior view. Horizontal section. Deep dissection.
See also
*
Internal capsule
The internal capsule is a paired white matter structure, as a two-way nerve tract, tract, carrying afferent nerve fiber, ascending and efferent nerve fiber, descending axon, fibers, to and from the cerebral cortex. The internal capsule is situate ...
*
Extreme capsule
References
External links
*
Image at Univ. of South Carolina
Cerebrum
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