Basal Ganglia and Internal Capsule

Question 1

function of basal ganglia

Answer 1

fine-tune voluntary movements and are therefore involved in the generation of goal-directed voluntary movements

Question 2

how do basal ganglia work

Answer 2

1. recive info from cerebral cortex
2. process and adjust this info
3. send it to thalamus
4. thalamus sends the adjusted into back to cortex
5. the cortex then sends its motor info to the skeletal muscles via the pyramidal system

Question 3

what are the basal ganglia

Answer 3

a group of subcortical nuclei that from part of the extra pyramidal system

Question 4

name the five pairs of nuclei that make up the basal ganglia

Answer 4

• caudate nucleus
• putamen
• globus pallidus
• subthalamic nucleus
• substantia nigra

Question 5

what does the striatum consist of

Answer 5

caudate nucleus and putamen

Question 6

what does the lentiform nucleus consist of

Answer 6

putamen, globus pallidus and subthalamic nucleus

Question 7

what is the caudate nucleus part of

Answer 7

striatum

Question 8

shape of caudate nucleus

Answer 8

c-shaped
made up of head, body and tail

Question 9

location of caudate nucleus

Answer 9

lateral to lateral ventricles

Question 10

that does the tail of the caudate nucleus from

Answer 10

roof of inferior horn of lateral ventricles and is terminated by connecting with amygdala

Question 11

function of caudate nucleus

Answer 11

sends information to thalamus concerning body and limb posture

Question 12

what is an underactive caudate nucleus linked to

Answer 12

depression and schizophrenia

Question 13

what is the putamen part of

Answer 13

striatum and lentiform nuclei

Question 14

shape of putamen

Answer 14

round

Question 15

location of putamen

Answer 15

medially: globus pallidus
laterally: external capsule

Question 16

putamen function

Answer 16

regulates motor functions

Question 17

what is the globus pallidus part of

Answer 17

lentiform nuclei

Question 18

globus pallidus location

Answer 18

medial to putamen

Question 19

function of globus pallidus

Answer 19

regulates movements to create smooth and precise actions

Question 20

substantia nigra location

Answer 20

• small motor nucleus in anterior part of upper mibrain
• functionally part of basal ganglia despite location in midbrain

Question 21

two components of substantia nigra

Answer 21

pars compacta and pars reticula

Question 22

what is the dorsal portion of the substantia nigra

Answer 22

pars compacts

Question 23

what is the pars compacts made up of

Answer 23

dense, dark, melanin-filled neurons

Question 24

what happens when the dopamine neurons in the pars compacta die

Answer 24

parkinson’s disease

Question 25

what is the ventral portion of the substantia nigra

Answer 25

pars reticula

Question 26

pars reticula function

Answer 26

plays a roll in controlling eye movements

Question 27

what is the internal capsule

Answer 27

mass of white matter which collects all axons beside the thalamus and the third ventricle

Question 28

function of the internal capsule

Answer 28

large number of motor and sensory fibres travel to and from the cortex via the internal capsule

Question 29

internal capsule location

Answer 29

bisects basal ganglia

Question 30

name the three subdivisions of the internal capsule

Answer 30

- anterior limb - genu - posterior limb

Question 31

two types of fibres found in anterior limb of internal capsule

Answer 31

- frontopontine fibres - thalamocortical fibres

Question 32

frontopontine fibres

Answer 32

frontal cortex to pons

Question 33

thalamocortical fibres

Answer 33

thalamus to frontal lobe

Question 34

what fibres are contained in the genu

Answer 34

corticobulbar fibres

Question 35

corticobulbar fibres

Answer 35

Cortex to brainstem

Question 36

what two types of fibres are contained in the posterior limb

Answer 36

- corticospinal fibres - ascending sensory fibres

Question 37

corticospinal fibres

Answer 37

cortex to spinal cord

Question 38

what part of the basal ganglia receive input from the cortex

Answer 38

the striatum

Question 39

where do the striatum not receive input from

Answer 39

primary visual and auditory cortices

Question 40

what are the input pathways of the basal ganglia collectively referred to as

Answer 40

corticospinal pathways

Question 41

where do axons with the striatum synsapse with

Answer 41

- The globus pallidus - The pars reticula of the substantia nigra (via striatonigral fibres)

Question 42

describe the output from the basal ganglia to the pars reticula of the substantia nigra

Answer 42

axons synapse with upper motor neurons in the superior colliculus to regulate eye movements

Question 43

describe output of the basal ganglia to the globus pallidus

Answer 43

axons synapse with the thalamus → thalamus relays this info back to the motor cortex (feedback loop)

Question 44

name five involuntary movement disorders

Answer 44

- tremor - athetosis - chorea - ballism - distonia

Question 45

athetosis

Answer 45

slow involuntary writhing or twisting movements of extremities

Question 46

chorea

Answer 46

fast or jerky writhing movemets of extremities

Question 47

ballism

Answer 47

similar to chorea but associated with more proximal extremities such as shoulders and hips

Question 48

distonia

Answer 48

involuntary contractions of muscles

Question 49

name five impairments to motion disorders

Answer 49

- akinesia - bradykinesia - shuffling gait - difficulties with speech - loss of postural reflexes

Question 50

akinesia

Answer 50

lack of movement

Question 51

bradykinesia

Answer 51

slowness of movement

Question 52

causes of parkinson's disease

Answer 52

* death of dopamine secretion in the substantia nigra * exact cause is unknown but may be associated with exposure to toxins, historical head trauma, infection and genetics

Question 53

two treatments for parkinson's disease

Answer 53

- L-DOPA - Deep brain stimulation

Question 54

explain how L-DOPA treats Parkinson's

Answer 54

its a dopamine precursor that helps alleviate symptoms. its initally effective but after 5-10 years, 50% of patients develop DOPA-induced dykinesia (involuntary erractic movements)

Question 55

explain how deep brain stimulation trats parkinsons

Answer 55

the activity of the subthalamic nucleus (STN) is increased in parkinsons, high frequency stimulation has been shown to deactivate the STN

Question 56

cause of huntingtons disease

Answer 56

progressive atrophy of the striatum that is genetic in origin

Question 57

treatment of huntington's disease

Answer 57

- xenazine: can supress involuntary movements but has multiple side effects that can cause drowsiness, restlessness and/or psychiatric conditions - the comorbidity of psychiatric disorders means many patients are treated with antidepressants and antipsychotic drugs