The Basal Ganglia Flashcards
Define the basal Ganglia
Large interconnected nuclear masses located deep within
1.Cereral hemispheres
2.Diencephalon
3.Mid brain
Functions of the Basal Ganglia?
1.Fine-tuning of voluntary movements
2.Control of posture
3.memory-storage of motor programs of familiar mot actions e.g signature
What system is the basal ganglia a part of?
Extra pyramidal system
What nuclei make up the basal ganglia?
1.corpus striatum
2.Subthalamic nucleus
3.Substantia Nigra
Where is the corpus striatum located?
Deep within the cerebral hemispheres.
What divides the corpus striatum?And what does it divide it into?
1.internal capsule
2.Caudate nucleus and the lentiform nucleus
What is the caudate nucleus divided into?
- head
2.Body
3.Tail
What shape is the caudate nucleus ?
Large C-shaped or coma shaped mass of grey matter
what is the caudate nucleus in close relation to?
Lateral ventricle
Describe the head of the caudate nucleus?
It is the large and rounded anterior part that forms the lateral wall of the anterior horn of the lateral ventricle.
It is continuous inferiorly with the putamen.
Describe the body of the caudate nucleus?
It is long and narrow and forms part of the floor of the body of the lateral ventricle.
Where does the body and the head of the caudate nucleus meet?
Interventricular foramen.
Describe the tail of the caudate nucleus.
long and narrow and lies in the roof of the inferior horn of the lateral ventricle.
What is the tail of the caudate nucleus continuous with?
amygdaloid nucleus
What makes up the lentiform nucleus?
Putamen and globus pallidus.
where is the putamen located?
Between the external capsule and the globus pallidus?
Where is the globus pallidus located?
Between the putamen and the internal capsule.
.
What 2 capsules surround the lentiform nucleus?
External capsule (laterally) and internal capsule
(medially)
What does the internal capsule separate?
The caudate nucleus& thalamus medially from the lentiform nucleus laterally
What does the external capsule separate?
The lentiform nucleus and claustrum
Where is the amygdaloid nucleus located?
In the temporal lobe, close to the Uncus.
Relation of the amygdaloid to the lateral ventricle
Lies Anterosuperior to inferior horn of lateral ventricle
What Is the amygdaloid nucleus connected to?
Tail of caudate nucleus
Function of the Amygdaloid nucleus and what systems part. of?
Smell center
limbic system
What is the claustrum medial to?
Insula
Relation of the sub thalamus to the thalamus?
Located ventral to the thalamus
The sub thalamus contains 3 nuclei, what are they and where are they located?
Zona incerta- dorsolaterally
prerubral field- dorsomedially
sub thalamic nucleus- ventral
What is the largest nucleus in the midbrain?
Substantia nigra
What two parts make up the substantia nigra?And their location?
Compact part – dorsal
Reticular part - ventrally
What are neurons in the pars compact filled with?
melanin
What neurotransmitter is produced by the substantial nigra?
Dopamine
Describe the different connections of the basal ganglia?
1.Input- from sources outside basal ganglia
2.Interconnections -between nuclear masses within the basal ganglia.
3.Output connections- from basal ganglia to other parts of the brain.
What are the afferent fibres of the corpus striatum and what neurotransmitter do they release?
1.Corticostriate-Glutamate
2.Thalamostriate
3.Nigrostriate-dopamine
4.Brain stem Strial Fibers-Serotonin
What part of the thalamus do the afferent fires come from?
intralaminar nucleus
What part of the cerebral cortex produces most of the afferent fibres?
The sensory cortex
Which two afferent fibres are inhibitory?
Nigrostriate Fibers
Brain stem Strial Fibers
What are the efferent fibres of the corpus striatum?And their neurotransmitters.
1.Striatopallidal fibers-GABA
2.Straiatonigral fibers-GABA,Substance P
What kind of neurons are found in the neostriatum?
Medium spiny neurons
What is the putamen functionally related to and what do the two constitute.
caudate nucleus
Neostriatum
other name for the globus pallidus
Pallidum or Paleostriatum
What are the manifestations the lesions of the basal ganglia?
1.Involuntary movement during rest
2.change in muscle tone
Causes and features of chorea?
lesion in the caudate nucleus
Involuntary,jerky,quick,irregular,non-repetitivepurposeless-movements
Types of Chorea?
1.Sydenham(Rheumatic fever)
2.Huntington’s Chorea
3.chorea gravidarum
4.chorea of contraceptive pills
Who is most likely to get Sydenham chorea?
Females
Define Huntington’s disease?
It is an autosomal dominant disease that results in the degeneration of the cerebral cortex and the basal ganglia.
At what age does deterioration of the brain begin and when do people usually die?
1.Between 30 and 40 yers of age.
2.15-20 years after onset of degeneration
Features of Huntington’s disease.
1.Twitching movements of the head.
2.Grimacing movements in the face, lips and tongue
3.Gesticulating movements in the distal parts of the upper limbs
4.Jerking movements in the distal parts of the lower limbs.
Lesion in athetosis?
Lesion in the Putamen and Globus pallidus
Features of Athetosis
: Involuntary, slow, sinuous, writhing movements involving distal part of limb (hand)
Lesion in Hemiballsimus?
Lesion of the subthalamus
Features in Hemiballsimus?
Sudden, involuntary, spasmodic movements that involves one limb or one side of the body (Limb suddenly flies about in all directions out of control
Other names for Parkinsonism?
Paralysis Agitans/Parkinson’s disease.
What causes Parkinsonism?
: Neuronal degeneration in substantia nigra leading to reduction of dopamine within corpus striatum.
Describe the pathophysiology of Parkinsonism?
Loss of nigrostriatal DA projection.
Features of Parkinsonism ?
Tremors,Rigidity,akinesia,posture
Describe the tremors?
Pill-rolling, involuntary, rhythmic, oscillating movements. It occurs during waking time during rest, it is called static tremors
Describe the rigidity experienced in Parkinsonism.
It occurs in both flexors, and extensors, but more in flexors giving flexion attitude.
It is called lead pipe rigidity.
Describe Akinesia experience in Parkinsonism.
it means lack of movement; Absence of swinging arm during walking, mask face, low- volume slow monotonous speech, and shuffling gait.
