Basal Ganglia Flashcards Preview

Anatomy > Basal Ganglia > Flashcards

Flashcards in Basal Ganglia Deck (47):
1

what is the definition of the basal ganglia

refers to structures that yield movement disorders when damaged

2

what is the striatum made up of

caudate nucleus
putamen

3

what is the lentiform nucleus made up of

putamen
globus pallidus

4

what are the two parts of the globus pallidus

globus pallidus interna (GPi)
globus pallidus externa (GPe)

5

what part of the basal ganglia is C-shaped w/a long tail that swings laterally

caudate

6

what part of the basal ganglia is just medial and coincides with the insula

putamen

7

what is the key "output" of the basal ganglia and where do most of the projections go

globus pallidus
-thalamus

8

where is the nucleus accumbens in reference to the basal ganglia structures

anterior, medial and inferior
****only see in cross section at HEAD level of caudate****

9

what seperates the putamen from the GPe

external medullary laminae

10

what does the internal medullary laminae separate

GPe from GPi

11

the substantia nigra is apart of the basal ganglia, what part of the brainstem can it be seen in cross section

rostral midbrain

12

the subthalamic nuclues is a part of the basal ganglia, where is it typically located in reference to the substantia nigra at midbrain cross section level

just on top and lateral to substantia nigra

13

what are the 2 parts of the substantia nigra ?

Compact - densely packed pigmented neurons
Reticular - nonpigmented neurons (more lateral)

14

what is the function of the compact part of substantia nigra ? What about the reticular part ?

Compact - DA projections to striatum
Reticular - output of Basal ganglia (like GP)

15

what limb of the internal capsule separates the caudate from the lenticular nucleus

anterior limb

16

what limb of the internal capsule separates the thalamus from the globus pallidus

posterior limb

17

what is the broad function of the basal gangli

modulate cortical output especially motor control

18

what are the 4 key players in the basal ganglia circuit or loop

cortex --> striatum --> globus pallidus --> thalamus ----> back to cortex

19

what are the main inputs of the BG circuit

cortical afferents to striatum

20

what are the main outputs of the BG circuit

Globus pallidus interna and reticular part of substantia nigra

21

The basal ganglia circuit or motor loop cannot influence the motor cortex directly. What does this mean ?

It must go through the thalamus, which is not apart of the BG its apart of the diencephalon

22

excitatory connections of the BG motor loop use what nuerotransmitter

glutamate

23

inhibitory connections of the BG motor loop use what nuerotransmitter

GABA

24

T/F in the striatum there is only one neurochemical territory

F, there are many nuerochemicla territories in the striatum

25

expain the direct or principal circuit of the basal ganglia

1 - excitatory input from cortex to striatum
2 - striatum sends inhibitory output to GPi
3 - GPi sends inhibitory output to VA/VL of thalamus
4 - thalamus sends excitatory input back to cortex

26

How could you manipulate the direct pathway to increase motor cortical output ?

Increase inhibition on GPi (GPi is now less active)

27

how does increasing inhibition on GPi result in increased cortical output

If increase inhibition on GPi, its less active so puts LESS inhibition on thalamus = more excitation to cortex = greater output

28

how would you decrease motor cortical output in the direct BG pathway

Increase excitation on GPi (now more active) = increased inhibition on thalamus = decreased excitation to cortex = decreased cortical output

29

the degeneration of ______ leads to huntington's disease

striatum

30

what is the main sign of huntingtons disease

chorea - rapid, rigid dance like movements of face and limbs

31

T/F Huntingtons disease is autosomal recessive disease

F, Autosomal dominant (meaning more number the repeats the faster the onset)

32

what are the 2 new additional BG structures involved in the indirect BG pathway that are not a factor in the direct pathway

subthalamus and GPe

33

explain the indirect pathway of the basal ganglia

1 - excitation input from cortex to
A) striatum or B) subthalamus
2 - A) striatum inhibitory to GPe = inhibition of subthalamu
B) subthalamus excitatory output to GPi
3 - GPi inhibitory output to thalamus
4 - thalamus excitatory input back to cortex

34

if you decrease the output of GPe in the basal ganglia indirect pathway, what will be the result ?

Decrease GPe inhibitory output on subthalamus = increased excitatory output to GPi=increased inhibition on thalamus = decreased excitatory input to cortex = decreased cortical output

35

if you were to increase the inhibitory output from GPe in the indirect BG pathway what would be the end result

decreased thalamic inhibition = increase cortical output

36

in strokes it is very common for the subthalamus to be damaged, how would this affect the indirect BG pathway

results in less excitatory input to GPi=decreased inhibition on thalamus= excessive increased excitatory input to cortex = TOO much cortical output

37

what is the dramatic movement disorder where limbs, usually on one side of the body, are flailing and rotating that is the result of a damaged subthalamus

hemiballismus

38

hemiballismus is the result of damage to what vessel ?

Posterior cerebral a. (PCA)

39

what is the role of the substantia nigra in the basal ganglia

Substantia nigra compact - sends DA input to striatum
Substantia nigra reticulata - sends output to thalamus

40

what part of the substantia nigra is similar to GPi in terms of their function

SNr similar to GPi b/c both are main outputs to thalamus of basal ganglia

41

what are the 3 cardinal features of Parkinson's disease

1 - bradykinesia
2 - resting tremors
3 - rigidity
***Need 2 of the 3 for diagnosis***

42

The loss of ______ neurons is a major characteristic of Parkinsons disease

Substantia nigra compacta

43

How does the loss of substantia nigra compacta affect cortical output in parkinsons disease

no DA projections to striatum = little inhibitory output to GPi (making more active) = increased inhibitory output to thalamus = decreased excitatory input to cortex = decreased cortical output = bradykinesia

44

what is the drug commonly used to treat parkinsons disease and how does it function

levodopa - precursor for DA so it acts to replace lost DA projections from degeneration of nigrostriatal fibers

45

if you were to treat parkinsons disease through a surgical approach, what part of the brain would you destroy and why ?

-remove GPi
*** removes massive inhibition on thalamus****

46

if you were to treat parkinsons disease by deep brain stimulation where would you implant the electrodes in the brain ?

subthalamus

47

if you were trying to treat parkinsons disease that affected the right limbs of the body, what side of pallidotomy would help reduce symptoms ?

Left side pallidotomy
**L basal ganglia controls L cortex which controls contralateral musculature***