Basal Nuclei – Anatomy
The basal nuclei are subcortical intracerebral masses of gray matter forming important parts of the extrapyramidal system.
The corpus striatum, which is partially divided by the internal capsule into two nuclei: (a) The caudate nucleus (b) The lentiform nucleus
The amygdaloid body forms a part of the limbic system.
Corpus striautm comprises the caudate nucleus and lentoform nucleus.
It is a C – shaped or comma – shaped nucleus which is surrounded by the lateral ventricle. The concavity of ‘C’ encloses the thalamus and the internal capsule.
The nucleus has a head, a body, and a tail.
The head forms and floor of the anterior horn of the lateral ventricle.
The body forms the floor of the central part of the lateral ventricle
The tail forms the roof of the inferior horn of the lateral ventricle and ends by joining the amygdaloid body at the temporal pole.
This is a large lens – shaped nucleus, forming the lateral boundary of the internal capsule. It lies beneath the insula and the claustrum.
The lentiform nucleus is divided into two parts by a thin lamina of white matter.
The larger lateral part is called the putamen. Structurally, it is similar to the caudate nucleus and contains small cells.
The smaller medial part is called the globus pallidus. It is made up of large cells.
Connections of Corpus Striatum
The caudate nucleus and putamen are afferent nuclei, while the globus pallidus is the efferent nucleus of the corpus striatum.
Functions of Corpus Striatum
The corpus striatum regulates muscle tone and thus helps in smoothening voluntary movements.
It controls automatically associated movements, like the swinging of arms during walking. Similarly, it controls the coordinated movements of different parts of the body for emotional expression.
It influences the precentral motor cortex which is supposed to control the extrapyramidal activities of the body.
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