Anatomy of the Basal Ganglia and the Cerebellum

Question 1

Label the cerebellum

Answer 1

Question 2

Label the brainstem and its attachments to the cerebellum

Answer 2

Question 3

Label the cerebellum

Answer 3

Question 4

What three layer is the cerebellum divided into?

Answer 4

Molecular layer (outer)

Purkinje cell layer (middle)

Granule cell layer (inner)

Question 5

What is the function of the Granular layer of the cerebellum?

Answer 5

The Granular Layer receives Afferent Projections (inputs) mainly from:

• Spinal cord, from somatic proprioceptors and pressure receptors.
• Cerebral cortex (relayed via the pons).
• Vestibular apparatus via the vestibular nuclei.

Question 6

What is the function of the Purkinje cell layer of the cerebellum?

Answer 6

Efferent Projections of the Cerebellum (outputs), from all three lobes of the cerebellum:

the only output is via the axons of Purkinje cells which mainly synapse on neurons of the deep cerebellar nuclei and subsequently contribute to coordinating the functions all of the motor tracts of the brainstem and spinal cord (corticospinal, vestibulospinal, rubrospinal tracts).

Most efferent axons of the deep cerebellar nuclei cross the midline and synapse in the thalamus. The thalamus in turn sends fibres to the motor cortex.

Question 7

Describe the clinical effects of a unilateral Cerebellar hemisphere lesion

Answer 7

Cerebellar hemispheres influence the ipsilateral side of the body, therefore lesions also lead to ipsilateral signs and symptoms (contrast with lesions of motor or sensory cortex).

Unilateral hemispheric lesion: Disturbance of coordination in limbs. Can result in intention tremor and unsteady gait in the absence of weakness or sensory loss.

Question 8

Describe the clinical effects of bilateral cerebllar dysfunction

Answer 8

Bilateral cerebellar dysfunction: Results in slowed, slurred speech (dysarthria), bilateral incoordination of the arms and a staggering, wide based gait (cerebellar ataxia).

Question 9

What kind of cerebellar dysfunction will acute alcohol poisoning cause?

Answer 9

Acute alcohol exposure typically results in bilateral cerebellar hemisphere dysfunction and presents with cerebellar ataxia.

Question 10

What clinical effects would a midline cerebellar lesion cause?

Answer 10

Midline lesion:

Disturbance of postural control. Patient will tend to fall over when standing or sitting despite preserved limb coordination.

Question 11

What are the basal ganglia, list the main 5

Answer 11

Basal Ganglia A number of masses of grey matter located near the base of each cerebral hemisphere

• Caudate Nucleus
• Putamen
• Globus Pallidus
• Subthalamic nucleus
• Sibstantia Nigra

Question 12

What are the main functions of the Basal Ganglia?

Answer 12

To facilitate purposeful movement.

Inhibit unwanted movements.

Role in posture and muscle tone.

Question 13

Label the group names associated with the basal ganglia

Answer 13

Question 14

Label the schematic of the basal ganglia system

Answer 14

Question 15

Label the shematic of basal ganglia and cerebellar interactions

Answer 15

Question 16

label the axial section

Answer 16

Question 17

Label the coronal section

Answer 17

Question 18

Through which part sturcture is this section? Label it

Answer 18

Mesencephalon (midbrain)

Question 19

Looking at the substantia nigra, how can parkinson’s disease be indentifed and why?

Answer 19

degeneration of dopaminergic neurons of the substantia nigra, it therefore looses its black clour.

The black pigment is neuromelanin, a by product of dopamine neurotransmitter production

Question 20

Which basal ganglia does the direct pathway concern, and what does it do?

Answer 20

Direct Pathway: Enhances outflow of thalamus, enhancing the desired movement (inhibition of thalamus inhibition)

Cortex - Putamen - Internal Globus Pallidus - Thalamus - Putamen

(Clever People Get Top Prizes)

Question 21

Which basal ganglia does the Indirect Pathway concern, and what does it do?

Answer 21

TBasal Ganglia Work With the Motor Cortex via the indirect pathway to Supress Unwanted Movement (inhibiting the inhibition of the excitory neurone that stimulates the neurone inhibiting the thalamus)

Cortex - Putamen - External globus pallidus - Subthalamic nucleus - Internal globus Pallidus - Thalamus

(Can People Eat So I Talk)

Question 22

Which side of the body will unilateral lesions of the basal ganglia affect?

Answer 22

The contralateral side

Question 23

What motor signs do lesions of the basal ganglia produce?

Answer 23

changes in muscle tone

dyskinesias (abnormal, involuntary movements) including: tremor (sinusoidal movements),

chorea (rapid, asymmetrical movements usually affecting distal limb musculature)

myoclonus (muscle jerks).

Question 24

What motor signs do lesions of the basal ganglia NOT produce?

Answer 24

Generally do not cause

• paralysis
• sensory loss
• loss of power
• ataxia

Question 25

What is the pathophysiology of Parkinson’s, and what are its signs?

Answer 25

Pathology: degeneration of dopaminergic neurons of the substantia nigra

Signs: akinesia, rigidity and resting tremor

Question 26

What is the pathophysiology and genetic trait of Huntington’s disease (chorea) and what are its signs?

Answer 26

Genetics: autosomal dominant disorder

Pathology: progressive degeneration of the basal ganglia and cerebral cortex

Signs: chorea and progressive dementia

Question 27

Describe the changes in basal ganlia pathways in Parkinson’s and Huntington’s chorea

Answer 27