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Functions of cerebellum

Functions

Division of cerebellum involved

1. Regulation of tone, posture and equilibrium

By receiving impulses from vestibular apparatus

Vestibulocerebellum

By receiving impulses from proprioceptors in muscles, tendons and joints, tactile receptors, visual receptors and auditory receptors

Spinocerebellum

2. Regulation of coordinated movements

1. Damping action

2. Control of ballistic movements

3. Timing and programming the movements

4. Servomechanism

5. Comparator function

Corticocerebellum (Neocerebellum)

BASAL GANGLIA PHYSIOLOGY

Basal ganglia are the scattered masses of gray matter submerged in subcortical substance of cerebral hemisphere. Basal ganglia form the part of extrapyramidal system, which is concerned with integration, and the regulation of motor activities.

COMPONENTS

1) Corpus striatum

2) Substantia nigra and

3) Subthalamic nucleus of Luys.

CORPUS STRIATUM

It is a mass of gray matter situated at the base of cerebral hemispheres in close relation to the thalamus. The internal capsule incompletely divides the corpus striatum into two parts.

1. Caudate nucleus

2. Lenticular nucleus.

1. Caudate Nucleus

This is an elongated arched gray mass, lying medial to internal capsule. Throughout its length, the caudate nucleus is related to lateral ventricle. Caudate nucleus has a head portion and a tail portion. The head is bulged into lateral ventricle and situated rostral to thalamus. The tail is long and arched. It extends along the dorsolateral surface of thalamus and ends in amygdaloid nucleus.

Fig.29. Basal ganglia.

Fig.30. Corpus striatum.

2. Lenticular Nucleus

It is a wedge shaped gray mass, situated lateral to internal capsule. A vertical plate of white matter called the external medullary lamina, divides lenticular nucleus into two portions.

a. The outer putamen and

b. The inner globus pallidus

Putamen and caudate nucleus are the phylogenetically newer parts of corpus striatum and these two parts are together called neostriatum or striatum. The globus pallidus is phylogenetically older part of corpus striatum. And, it is called pallidum or paleostriatum. The globus pallidus has two parts, an outer part and an inner part.

SUBSTANTIA NIGRA

This is situated below red nucleus. It is made up of small unpigmented and large pigmented cells. The pigments have high of quantity of iron.

SUBTHALAMIC NUCLEUS OF LUYS

This is situated lateral to red nucleus and dorsal to substantia nigra.

BASAL GANGLIA CONNECTIONS

The afferent and efferent connections of corpus striatum (Figs 29 and 30), substantia nigra and subthalamic nucleus of Luys are given in Table below In addition to afferent and efferent connections, the different components of corpus striatum of the same side are interconnected by intrinsic fibers.

1) Putamen to globus pallidus

2) Caudate nucleus to globus pallidus

3) Caudate nucleus to putamen

The different components of corpus striatum in each side are connected to those of the opposite side by commissural fibers.

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