Basal nuclei

Question 1

What is the function of the basal nuclei?

Answer 1

Assists in planning and organization of movements through activation of motor association cortex

Question 2

What are the components of the basal nuclei?

Answer 2

Caudate nucleus
Putamen
Globus pallidus

Question 3

The anatomical divisions of the basal nuclei include

Answer 3

Caudate nucleus and lentiform nucleus (globus pallidus and putamen)

Question 4

The functional divisions of the basal nuclei include

Answer 4

Striatum (caudate nucleus and putamen)
Pallidum (globus pallidus)

Question 5

What other two areas besides the striatum and pallidum are included when considering functional activity of the basal nuclei?

Answer 5

Subthalamic nucleus
Substantia nigra

Question 6

Direct pathway of a signal through the basal nuclei

Answer 6

Input from cerebral cortex to striatum (corticostriate)
Connection from striatum to globus pallidus (striatopallidal)
Output from globus pallidus to ventral anterior nucleus of thalamus (pallidothalamic)
Thalamic fibers project to premotor cortex (thalamocortical)

Question 7

What is the purpose of the direct pathway of the basal nuclei?

Answer 7

Basal nuclei takes information about body position to plan and organize body movement

Question 8

The direct pathway connects to the substantia nigra through

Answer 8

The striatum

Question 9

The direct pathway connects to the subthalamic nucleus through

Answer 9

Globus pallidus

Question 10

What is the purpose of the direct pathway of the basal nuclei?

Answer 10

Excitatory, “the accelerator”
Enhances motor output related to agonist muscles

Question 11

What is the purpose of the indirect pathway of the basal nuclei?

Answer 11

Inhibitory, “the brake”
Decreases motor output related to antagonist muscles
Includes detour through subthalamic nucleus

Question 12

What is the purpose of the substantia nigra in the basal nuclei?

Answer 12

Dopamine input
Helps excite direct pathway
Helps inhibit indirect pathway
Dopamine enhances speed and/or force of movement

Question 13

Where does the blood supply of the basal nuclei come from?

Answer 13

Lenticulostriate arteries of MCA supplies globus pallidus, putamen, caudate nucleus
Leaves perforation in the brain matter where the arteries go through the cerebral cortex

Question 14

What does “negative” signs mean?

Answer 14

Actions the patient wants to perform but cannot
Also called hypokinetic signs

Question 15

What are negative signs of basal nuclei disorders?

Answer 15

Akinesia
Bradykinesia
Abnormal postural adjustments
Dystonia

Question 16

What is akinesia, bradykinesia, abnormal postural adjustments, dystonia?

Answer 16

Akinesia: hesitancy in starting movement
Bradykinesia: slowness of execution of movement
Abnormal postural adjustments: head and trunk flexion and inability to make appropriate adjustments when falling or tilting or standing
Dystonia: unusual fixed posture which occur spontaneously

Question 17

What does “positive” signs mean?

Answer 17

Actions the patient does not want to perform but cannot prevent
Hyperkinetic signs

Question 18

What are the two types of positive signs of basal nuclei disorders?

Answer 18

Dyskinesia (involuntary movements that cannot be controlled)
Rigidity (tone in all muscles acting on a joint is increased, hypertonicity)

Question 19

Positive signs: different types of dyskinesia (5)

Answer 19

Tremors: rhythmic movements in distal limbs (resting tremor)
Chorea: rapid jerky movements in distal limbs
Athetosis: slow writhing movements of an entire limb
Ballismus: violent flinging movements of an entire limb
Tics: repetitive movements

Question 20

Positive signs: different types of rigidity

Answer 20

Lead pipe: Increased resistance to passive movement in both flexors and extensors (tested with passive movement of limbs)
Cogwheel: ratchet-like movement at frequency resting tremors

Question 21

What are the symptoms of Parkinson’s disease?

Answer 21

Akinesia
Bradykinesia
Resting tremor

Question 22

What is the pathology that leads to Parkinson’s disease?

Answer 22

Loss of dopaminergic input from substantia nigra
Consequence of degenerative, vascular, or inflammatory change

Question 23

Etiology of Parkinsons can be

Answer 23

Genetic, due to trauma, or unknown

Question 24

Parkinsons affects which pathways of the basal nuclei

Answer 24

Direct and indirect pathways

Question 25

Epediomology of Parkinsons disease

Answer 25

Initial symptoms start at 45 to 65 years of age
Incidence 1/500 with 50000 new cases each year

Question 26

What are the symptoms of Huntington’s disease?

Answer 26

Chorea
Progressive dementia in the late stage
A lot of involuntary movements, balance not affected but lots of jerky movements

Question 27

What is the pathology of Huntington’s disease?

Answer 27

Degeneration of neurons in striatum for indirect pathway (this pathway is inhibitory so there is disruption that leads to involuntary movements)

Question 28

Huntingtons is an _____ disorder

Answer 28

Autosomal dominant genetic disorder

Question 29

With Huntington’s disease, motor activity is released from

Answer 29

Inhibitory control of indirect pathway