BASAL
GANGLIA
Dr. MRITUNJAY PANDEY
BASAL GANGLIA
Includes sub-cortical masses of grey
matter, situated in white core of each
cerebral hemisphere.
It includes:
Corpus striatum: Caudate &
Lentiform nucleus.
Claustrum
CORPUS STRIATUM
Divided almost completely by the fibres of
internal capsule into a medial part, the
Caudate nucleus and a lateral part, the
Lentiform nucleus.
Head of caudate nucleus and lentiform nucleus
are, connected by a band of grey matter below
the anterior limb of internal capsule.
CAUDATE NUCLEUS
Large comma-shaped mass of grey matter,
surrounds the thalamus and intimately
related to lateral ventricle.
Consists of a large head, body and thin tail.
Head is the rounded anterior part in front
of the inter-ventricular foramen and forms
the floor and lateral wall of the anterior
horn of lateral ventricle.
CAUDATE NUCLEUS
The body extends backward as a
continuation of head from the level of
inter-ventricular foramen along the floor
of central part of lateral ventricle.
The body of the caudate nucleus is
separated from the thalamus by stria
CAUDATE NUCLEUS
Tail is long and slender, forms the roof of
the inferior horn of lateral ventricle.
Close to the tip of the roof of inferior horn,
the tail is continuous with the amygdaloid
body.
Tail of caudate nucleus is related above
with:
Thalamus, separated by sublentiform part of IC.
Globus pallidus, separated by external capsule
LENTIFORM NUCLEUS
Large, biconvex mass of grey mater.
Lies lateral to the internal capsule.
Laterally, separated from the claustram
by fibres of external capsule.
Superiorly, the lentiform nucleus is
related to corona radiata and inferiorly
to sublentiform part of internal capsule.
LENTIFORM NUCLEUS
Lentiform nucleus is further subdivided by
external medullary lamina into an outer part,
the Putamen and an inner part, the Globus
pallidus.
Globus pallidus is further separated into outer
and inner segments by an internal
medullary lamina.
Connections and functions of caudate nucleus
and putamen are similar and collectively
called the neo-striatum or striatum.
CONNECTIONS OF CORPUS STRIATUM
The striatum (caudate nucleus & Putamen) is
receptive part while globus pallidus is the efferent
part.
Afferent connections: striatum receives afferents
from:
Ipsilateral cerebral cortex via corticostriate fibres.
Intralaminar nuclei of thalamus via thalamostriate
fibres.
Pars compacta of substantia nigra via nigrostriate
fibres.
Noadrenergic fibres from the locus coeruleus.
CONNECTIONS OF CORPUS
STRIATUM
Efferent connections: main output of
striatum is concentrated upon the globus
pallidus and on the substantia nigra.
Outflow from globus pallidus form 4 separate
bundles:
Fasciculus lenticularis
Ansa lenticularis
Subthalamic fasciculus
Pallidonigral fibres
CORPUS STRIATUM
Functions:
Mediates enormous number of
autonomic activities involved in normal
motor functions like swinging of arms
during walking.
Helps in smoothening voluntary motor
activities of body.
CLAUSTRUM
Thin lamina of grey matter that lies
lateral to the lentiform nucleus.
Separated from the latter by fibres of
external capsule.
Laterally, it is separated by a thin layer
of white matter from the cortex of insula.
Its connections and functions are
AMYGDALOID NUCLEAR COMPLEX
The complex, also called as amygdaloid
body or amygdala; lies in the temporal
lobe of cerebral hemispheres.
Lies deep to the uncus.
Related to the anterior end of inferior
horn of the lateral ventricle.
Functionally related to limbic system.
SUBSTANTIA NIGRA
It is a large motor nucleus present in the
midbrain.
The nucleus consists of two parts- ventral part
(Pars reticulata) and dorsal part (Pars
compacta).
Pars reticulata is related functionally to the
SUBSTANTIA NIGRA
Connections:
Pars compacta sends a dopaminergic
projection to striatum.
A projection from striatum ends in the
pars reticularis of substantia nigra.
This part also receives fibres from the
pallidum directly or after relay in
subthalamic nucleus.
SUBSTANTIA NIGRA
Connections:
Pars reticularis projects to the ventral
lateral nucleus of the thalamus.
These impulses are relayed to cingulate
and prefrontal areas of the cerebral
cortex.
Other efferents of pars reticularis reach
the superior colliculus.
VENTRAL STRIATUM AND
PALLIDUM
Some masses of grey matter lying in the
region of the anterior perforated substance
are now described as ventral striatum.
Anterior part of caudate and lentiform nuclei
fuse inferiorly to form the fundus striati.
Immediately below the fundus striati, there
is the olfactory tubercle.
VENTRAL STRIATUM AND PALLIDUM
More medially, there is a mass of grey
matter called the nucleus accumbens.
The ventral striatum consists of
olfactory tubercle and nucleus accumbens.
The part of the globus pallidus lying
inferior to the anterior commissure is
called the ventral pallidum.
BLOOD SUPPLY
The basal ganglia is supplied by:
Lenticulostriate branches of middle
and anterior cerebral arteries.
Anterior choroidal branches of
internal carotid artery.
CLINICAL ANATOMY
Involvement of basal ganglia results in
unwanted involuntary movements
(dyskinesis)- hyprkinetic or hypokinetic.
Dyskinetic movements include tremors,
chorea, athetosis and ballism.
Parkinson’s disease
LIMBIC SYSTEM
Consists of several cortical and sub-
cortical structures, which form a ring-like
structure around the upper end of
brainstem.
Phylogenetically oldest part of cerebral
cortex.
Formerly called rhinencephalon because
COMPONENTS
Cortical regions include limbic lobe and
hippocampal formation.
Subcortical structures include:
Amygdaloid nuclear complex
Septal nuclei
Hypothalamus
Anterior nucleus of thalamus
Olfactory areas.
FUNCTIONS OF LIMBIC SYSTEM
Integration of olfactory, visceral and
somatic impulses reaching the brain.
Control of activities necessary for
survival, like procuring of food and
eating behaviour, sexual behaviour.
Emotional behaviour
Retention of recent memory.
