2. BASAL GANGLIA
A GROUP OF NUCLEI IN THE
BRAIN ASSOCIATED WITH MOTOR
AND LEARNING FUNCTIONS
3. • THESE ARE THE
SCATTERD MASSES
OF GREY MATTER
SUBMERGED IN
SUBCORTICAL
SUBSTANCE OF
CEREBRAL CORTEX
4. • THE TERM BASAL
GANGLIA PERHAPS
ORIGINATED AS MOST
OF THE STRUCTURES
IN IT DEVELOPED
FROM THE BASEMENT
MEMBRANE OF
GROWING LATERAL
VENTRICLE IN
INTRAUTERINE LIFE.
5. INTRODUCTION
• Basal ganglia are the scattered masses of
gray matter submerged in sub cortical
substance of cerebral hemisphere
• Basal ganglia form the part of extra
pyramidal system , which is concerned
with integration , regulation of motor
activities .
7. 1.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 in to
two parts.
i. Caudate nucleus
ii. Lenticular nucleus.
8.
9. a) Caudate nucleus
• It is the smaller anterior part &lies medial
to internal capsule.
• It has head & tail portion .
• The head is bulged into lateral
ventricle.The tail is long & arched .It
extends along the dorsolateral surface of
thalamus & ends in amygdaloid nucleus.
10. b) Lenticular nucleus
• It is the larger posterior part lies lateral to
the internal capsule.
• It is subdivided into :
a) The outer putamen
b)The inner globus pallidus
11. 2.SUBSTANTIA NIGRA
-It is crescentric mass
of nerve cells
containing melanin.
-This is situated below
red nucleus ,
between the crus
cerebri & tegmentum
of midbrain.
12. 3.SUBTHALAMIC NUCLEUS OF
LUYS.
• It lies lateral & ventral to the red nucleus &
dorsal to the substantia nigra .
• It is connected with red nucleus ,
substantia nigra, globus pallidus.
• Functionally it is believed to be a part of
extrapyramidal system.
13. CONNECTIONS OF BASAL GANGLIA
• CONNECTIONS OF CORPUS STRIATUM
i) Afferent connections – corpus striatum
recieves afferent fibres from the following:
a)thalamic nuclei to caudate nucleus
&putamen.
b)cerebral cortex to caudate nucleus &
putamen.
c)substantia nigra to putamen
d)subthalamic nucleus to globus pallidus
17. INTRINSIC FIBRES OF CORPUS STRIATUM
The intrinsic fibres of corpus striatum of
same side are :
1. Putamen to globus pallidus .
2. Caudate nucleus to globus pallidus.
3. Caudate nucleus to putamen.
19. CONNECTIONS OF SUBSTANTIA
NIGRA
Afferent fibres from Efferent fibres
to
1.Putamen 1Putamen
2.Frontal lobe of cerebral
Cortex
3.Superior colliculus
4.Mamillary body of hypothalamus
5.Medial & lateral lemnisci
6.Red nucleus
21. FUNCTIONS OF THE BASAL
GANGLIA
1.It is the primitive motor cortex for
voluntary muscular activity.
- The movements during voluntary motor activity
are initiated by cerebral cortex , which are
controlled by basal ganglia
- During the lesions of basal ganglia , this
controlling mechanism is lost & so movements
become inaccurate & awkward.
22. 2.Controls reflex muscular activity
-The reflex muscular activities particularly visual
& labyrinthine reflexes are important in the
maintenance of posture.
-The co ordination & integration of impulses for
these activities depend upon basal ganglia.
3.Controls automatic & associated
movements.
-These movements , normally initiated by area 6 ,
mediated through corpus striatum, such as
swinging of arm during walking.
23. 4. Checks abnormal involuntary movements-
In lesion of the corpus striatum , abnormal
involuntary movements occur.
5. Controls the group movements for
emotional expressions-
Subject suffering from striatal diseases show
lack of emotional expression(Mask like
appearance)
24. 6. Red nucleus – is a relay station & a
coordinating centre for many motor &
sensory impulses.
7. Substantia nigra – It is regarded as the
centre for skilled movements.
26. 1.PARKINSON’S DISEASE
• The Parkinson’s disease is named after the
discoverer James Parkinson .
• It occurs due to damage of basal ganglia .
• It is mostly due to destruction of substantia
nigra & nigro strial pathway , which has
dopaminergic fibres
• This disease is also called as paralysis agitans
27. Causes of parkinsonism
• Viral infections of brain like encephalitis.
• Injury to basal ganglia
• Destruction or removal of dopamine in
basal ganglia. (due to antihypertensive
drugs & so called as drug induced
parkinsonism)
• Unknown cause.
28. Symptoms of Parkinsonism
• Rigidity
• Poverty of movements
• Tremor
• Akinesia or hypokinesia
• Gait
• Emotional changes
29. 1.RIGIDITY: Due to the removal of inhibitory
influence on gamma motor neurons , the muscle
tone is increased leading to rigidity .This affects
both flexor & extensor muscles equally. So ,the
limbs become more rigid like pillars .The
condition is called as lead pipe rigidity
2.POVERTY OF MOVEMENTS: Due to the
absence of automatic associated movements,
there is poverty of movements .The body
becomes statue like .The face becomes mask
like ,due to absence of appropriate expressions.
30. 3.TREMOR: Rapid alternate rhythmic &
involuntary movements of flexion & extension in
the joints of fingers &wrist or elbow is called
tremor .In parkinsonism the tremor occur during
rest & disappears while doing any work so it is
called static or resting tremor.
It is also called drum beating tremor as the
movements are similar to beating a drum .The
thumb moves rhythmically over the index &middle
finger .This is known as pill rolling movements.
31. 4.AKINESIA / HYPOKINESIA-
The patient is unable to initiate the voluntary
activity (Akinesia).or the voluntary movements are
reduced (hypokinesia).
This is because of hypertonicity of the muscles.
5.GAIT – In Parkinsonism, the gait is called festinant
gait.The patient walks quickly in short steps by
bending forward as if he or she is going to catch up
the centre of gravity.
32. TREATMENT FOR
PARKINSONISM
• It is treated by dopamine.
• Inj. Levodopa.:-This crosses the blood
brain barrier &after reaching brain ,it is
converted into dopamine.
33. 2.WILSON’S DISEASE
• This is also known as progressive
hepatolenticular degeneration .
• This disease develops due to damage of
lenticular nucleus particularly, putamen
• The degenerative changes in liver &brain
are due to disturbed copper metabolism .
34. 3.CHOREA
• This is an abnormal involuntary
movements .chorea means rapid jerky
movements .
• Mostly involves limbs.
• It is due to lesion in caudate nucleus
&putamen.
35. 4.ATHETOSIS
• This is another type of abnormal
involuntary movements ,which refers to
slow rhythmic & twisting movements .
• The cause for this lesion in caudate
nucleus & putamen
36. 5.HUNTINGTON’S CHOREA
• This disease is characterized by chorea
,hypotonia & dementia .
• It occurs due to degeneration of neurons
secreting GABA in globus pallidus
&substantia nigra .
37. 6.HEMIBALLISMUS
• It is characterised by violent involuntary
abnormal movements on one side of body
mostly the arm .
• While walking , the arm swings widely .These
movements are called flinging movements .
• Hemiballismus occurs due to degeneration of
subthalamic nucleus of Luys.
