Basal ganglia

Question 1

What are the components of the striatum?

Answer 1

1. Caudate nucleus
2. Putamen

Question 2

What are the components of the basal ganglia?

Answer 2

1. Putamen
2. Caudate nucleus
3. Globus pallidus

Question 3

What are the structures functionally associated with the basla ganglia?

Answer 3

1. Thalamus + subthalamic nucleus (nuclei of diencephalon)
2. Substantia nigra (nucleus of midbrain)

Question 4

What is the structure of the caudate nucleus?

Answer 4

“Tadpole-shaped” with head, body and tail

Question 5

What are the relations of the caudate nucleus to the lateral venticles?

Answer 5

• Head of caudate = Lateral walls of anterior horn of LV
• Body of caudate = Lateral walls of middle part of LV
• Tail of caudate = Roof of posterior horn of LV

Question 6

What happens to the caudate nucleus and putamen in ventral aspects of the brain?

Answer 6

Joins together to form ventral stritum, in which the nucleus accumbens is located.

Question 7

What is the structure of the globus pallidus?

Answer 7

• External segment
• Internal segment

Question 8

What structures do the internal segment of globus pallidus project into?

Answer 8

• Motor areas of the thalamus:
  1. Ventro-lateral thalamus
  2. Ventro-anterior thalamus
• Medial nucleus of the thalamus

Question 9

What structures do the external segment of the globus pallidus project into?

Answer 9

Subthalamic nucleus

Question 10

Which parts of the brain do the caudate nucleus receive projections from primarily?

Answer 10

Prefrontal cortex

Question 11

Which parts of the brain do the putamen receive projections from primarily?

Answer 11

Sensorimotor cortex

Question 12

What are the relations of the putamen?

Answer 12

Medial to the insula and lateral to the internal capsule

Question 13

What are the types of fibres found in the internal capsule?

Answer 13

• Efferent:
  1. Corticobulbar fibres
  2. Corticospinal fibres
  3. Corticopontine fibres
• Afferent: Thalamocortical fibres

Question 14

What are the origins of the corticospinal/corticobulbar tracts?

Answer 14

Motor cortex

Question 15

What are the functions of the corticospinal tract?

Answer 15

Projects into spinal cord and mediates voluntary movements of the muscles of the body.

Question 16

What are the functions of the corticobulbar tract?

Answer 16

Projects into the medulla and the nuclei of cranial nerves responsible for controlling movements of the head and neck.

Question 17

What are the origins of the corticopontine tract?

Answer 17

1. Sensorimotor areas
2. Premotor areas
3. Supplementary motor areas
4. Other higher sensory areas

Question 18

What are the functions of the corticopontine tract?

Answer 18

Fibres enter the pons and synapse at the pontine nuclei. Fibres from the nuclei subsequently project into the cerebellum via the middle cerebellar peduncle.

Question 19

What are the origins of the thalamocortical tract?

Answer 19

Thalamic nuclei

Question 20

What is the function of the thalamocortical tract?

Answer 20

Projects into the cortex and carries fibres from the thalamus (e.g. auditory/optic radiations from the medial/lateral geniculate nuclei)

Question 21

Why does the substantia nigra appear dark?

Answer 21

Production of melanin as by-product of dopamine synthesis

Question 22

What is the blood supply to the striatum?

Answer 22

Branches of the anterior and middle cerebral arteries, with most important branches termed “striate arteries”

Question 23

Which part of the internal capsule is most likely to be damaged following CVA?

Answer 23

Genu

Question 24

What are extrapyramidal motor disorders?

Answer 24

Motor disorders due to areas of the brain outside the motor cortex, internal capsule and corticospinal tract system.