The Nervous System (Part 4)
April 18th 2008 03:11
The White Matter of the Cerebrum
The white matter of the cerebrum as stated earlier is composed of myelinated nerve fibers located centrally. Varieties of such are the transverse commissural fibers, the projection fibers, and the association fibers.
The transverse commissural fibers interconnect the two hemispheres. Examples are the corpus callosum, anterior commissure, and hippocampal commissure.
The projection fibers connect cerebral hemispheres with other portions of the brain and spinal cord.
The association fibers connect different portions of the cerebral hemispheres, allowing cortex to function as an integrated whole.
The Basal Ganglia
The term basal nuclei is applied to a collection of masses of gray matter situated deep within each cerebral hemisphere. They are the corpus striatum, the amygdaloid nucleus, and the claustrum.
Generally the basal ganglia are association sites for motor control, complimented by other brain nuclei located in the subthalamus and the midbrain (extrapyramidal structures).
If the frontal lobe sends the commands and information for body movements, the extrapyramidal structures are the ones responsible in controlling the intensity, velocity, distance, and other aspects of movement.
The corpus striatum is located lateral to the thalamus. It is completely divided into two by the internal capsule. The two divisions of the corpus striatum are the caudate nucleus and the lentiform nucleus.
The lentiform nucleus is a wedge-shaped mass of gray matter whose base is oriented laterally and blade medially. The structure that separates it from the claustrum is the external capsule. The nucleus is divided into an outer, darker internal portion, the putamen and an inner, lighter portion, the globus pallidus.
The amygdaloid nucleus is within the temporal lobe close to the uncus.
On the other hand the claustrum is a thin sheet of gray matter, the function of which is unknown.
The white matter of the cerebrum as stated earlier is composed of myelinated nerve fibers located centrally. Varieties of such are the transverse commissural fibers, the projection fibers, and the association fibers.
The transverse commissural fibers interconnect the two hemispheres. Examples are the corpus callosum, anterior commissure, and hippocampal commissure.
The projection fibers connect cerebral hemispheres with other portions of the brain and spinal cord.
The association fibers connect different portions of the cerebral hemispheres, allowing cortex to function as an integrated whole.
The Basal Ganglia
The term basal nuclei is applied to a collection of masses of gray matter situated deep within each cerebral hemisphere. They are the corpus striatum, the amygdaloid nucleus, and the claustrum.
Generally the basal ganglia are association sites for motor control, complimented by other brain nuclei located in the subthalamus and the midbrain (extrapyramidal structures).
If the frontal lobe sends the commands and information for body movements, the extrapyramidal structures are the ones responsible in controlling the intensity, velocity, distance, and other aspects of movement.
The corpus striatum is located lateral to the thalamus. It is completely divided into two by the internal capsule. The two divisions of the corpus striatum are the caudate nucleus and the lentiform nucleus.
The lentiform nucleus is a wedge-shaped mass of gray matter whose base is oriented laterally and blade medially. The structure that separates it from the claustrum is the external capsule. The nucleus is divided into an outer, darker internal portion, the putamen and an inner, lighter portion, the globus pallidus.
The amygdaloid nucleus is within the temporal lobe close to the uncus.
On the other hand the claustrum is a thin sheet of gray matter, the function of which is unknown.
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