MOTOR SYSTEM : BASAL GANGLIA

Question 1

Basal ganglia major function is

Answer 1

provide a feedback mechanism to the cerebral cortex for the initiation and control of motor
responses.

Question 2

basal ganglia consist

Answer 2

neostriatum (caudate nucleus and putamen)
paleostriatum (globus pallidus)
Two additional nuclei, the subthalamic nucleus and substantia nigra,

Question 3

The primary regions of the basal ganglia that serve as afferents (receiving areas from the cortex) are the

Answer 3

caudate nucleus and putamen (neostriatum).

Question 4

major outputs of the basal ganglia arise from neurons located
in the

Answer 4

medial pallidal segment.

These neurons give rise to two fiber
bundles, the ansa lenticularis and lenticular fasciculus, which supply
thalamic nuclei.

Question 5

thalamic fasciculus

Answer 5

lenticular fasciculus and ansa
lenticularis

Question 6

a tract connecting the globus pallidus (internus) to the
thalamus.

Answer 6

Lenticular fasciculus

Question 7

principal inputs from the primary motor, secondary motor, and primary somatosensory regions of cortex are directed to

Answer 7

Putamen

Question 8

caudate nucleus, receives inputs from

Answer 8

cortical association regions
frontal eye fields
limbic regions of cortex

Question 9

BG receive inputs from

Answer 9

thalamus (centromedian nucleus), substantia nigra
subthalamic nucleus.

Question 10

Dopamine is produced in the

Answer 10

Pars Compacta of the substantia nigra

Question 11

D2 receptors in the neostriatum if activated

Answer 11

inhibit
GABA-neurons

Question 12

D1 receptors if activated

Answer 12

stimulate GABA-neurons

Question 13

two principal
components of substiantia nigra

Answer 13

pars compacta
pars reticulata : receives an inhibitory
(GABA)-ergic input from the neostriatum.

(which is excitatory when acting through D1 receptors and inhibitory when acting through D2 receptors).

Question 14

movement control system of the basal ganglia

Answer 14

Indirect pathway
Direct pathway

Question 15

Activation of the direct pathway
causes

Answer 15

excitation of the motor
cortex and thus facilitates
movements

Question 16

Activation of the indirect pathway

Answer 16

inhibits cortical-induced
movements

Question 17

pathway of direct pathway

Answer 17

cortex : Glutamate+ve {Neostriatum activation} ~ GABA -ve {inhibition of Globus pallidus medialis} ~. Disinhibition of thalamus which leads to excitation of motor cortex ~ stimuli is sent to spinal cord then to skeletal muscle

Question 18

Pathway of indirect pathway

Answer 18

cortex : Glutamate+ve {Neostriatum activation} ~ GABA -ve {inhibition of Globus pallidus lateralis} ~. Disinhibition of subthalamic nucleus ~ leads to activation of Globus medialis i.e Glu +ve (increase inhibition of thalamus) ~ stimuli is sent to spinal cord then to skeletal muscle

Question 19

Degenerative disease that affects the substantia nigra (depletion of dopamine) and it’s projections to the striatum

Answer 19

Parkinsons’s disease

Question 20

Parkinsons’s disease symptoms

Answer 20

masked face (no facial expression)>stooped posture, bradykinesia, shuffling gait, pill rolling tremor
Lewy bodies in the melanin containing neurons of the substantia nigra

reduced red nucleus

Question 22

Analog of meperidine (Damerol) - MPTP(Methylphenyltetrahyropyridine) can induce parkinsonism by

Answer 22

damaging dopaminergic neurons in the substantia nigra

Question 23

Huntington’s disease involeves

Answer 23

ADID of chromosome 4 - degenration of cholinergic and GABA-ergic neurons of the striatum
gyral atrophy in the frontal and temporal lobes

Question 26

choeriform dyskinesia often in girls after rheumatic fever

Answer 26

Sydenham’s chorea (St. Vitus dance )

Question 27

movement disorder due to vascular lesion in the subthalamic nucleus - C/L violent flinging (ballistic movements of 1/both extremities)

Answer 27

Hemiballism (there is loss of excitatory neurons from the subthalamic nucleus) to the GP mediallis

Question 28

ARID (chromosome 13) with a defect in copper metabolism leading to wing-beaiting tremor. Lesions in the lentiform nucleus (globbus pallidus and putamen)

Answer 28

Wilson’s disease
Tx; penicillamine ( a chelator)

Question 29

brief involuntary movements in forms of motor and vocal tics: repition of words, repeating words of others anf offensive words
motor tics : eye blinking, shrugging

Answer 29

Tourette syndrome