Motor Systems

Question 1

Name the two pyramidal tracts

Answer 1

Corticospinal
Corticobulbar
For voluntary movement

Question 2

What is the difference between pyramidal and extrapyramidal tracts?

Answer 2

Pyramidal arise from the motor neurons of the cerebral cortex and pass through the medullary pyramids whereas the extrapyramidal arise from brain stem motor nuclei and do not pass through the pyramids

Question 3

List the extrapyramidal tracts

Answer 3

Tectospinal tract
Rubrospinal tract 
Reticulospinal tract 
Vestibulospinal tract 
Unconscious reflexive movement

Question 4

What occurs when the primary motor, premotor and primary sensory cortex are damaged?

Answer 4

Primary: lesion causes paresis (muscle weakness)
Premotor: apraxia (lack of skilled movement)
Primary sensory: disturbance, degeneration of motor actions

Question 5

What are the two corticospinal tracts and are they ipsilateral or contralateral?

Answer 5

Anterior corticospinal tract: ipsilateral

Lateral corticospinal tract: contralateral

Question 6

What type of fibres are they pyramidal tracts?

Answer 6

Projection

Question 7

What part of the IC does the pyramidal tracts pass through?

Answer 7

Corticobulbar: genu of IC
Corticospinal: posterior limb

Question 8

Describe the lateralcorticospinal tract

Answer 8

Begins in M1, projects through the posterior limb of the IC, through crus cerebri, decussates at the medullary surface, tract continues through the LATERAL funiculus and terminates on the ventral horn of the spinal cord (cervical and lumbosacral)

Distal limb (hand) control

Question 9

Describe the anterolateral tract

Answer 9

Begins in M1, projects through the posterior limb of the IC, through crus cerebri, through anterior funiculus and decussates at different spinal cord levels
Innervates neck and trunk muscles

Question 10

The pyramidal pathway regulates which extrapyramidal pathways?

Answer 10

Reticulo and rubrospinal

Question 11

What pathways go through the tegmentum? What nuclei?

Answer 11

ALL ascending pathways.

ALL brain stem nuclei besides pontine nuclei

Question 12

What pathways does the base contain?

Answer 12

ALL descending pathways

Question 13

Describe the reticulospinal tract

Answer 13

Cell bodies are in the pontine and rostral medullary reticular formation. Ipsilateral and bilateral projection to all levels of the spinal cord to the ventral funiculus.

Extensor biased, balance, locomotion, postural reflex

Question 14

Describe the vestibulospinal tract

Answer 14

Lateral vestibulospinal tract: muscle tone in back and limb extensors –> balance (lateral vestibular n)

Medial vestibulospinal tract: stabilise head during movement (medial vestibular n)

Question 15

Describe the tectospinal tract

Answer 15

Cell bodies are located in the sup. colliculus, decussation @ midbrain and terminate at MNs at cervical spinal cord

Small portion travels ipsilaterally to inhibt muscles on one side while the contralteral muscles are excited (reflex arc)

Reflex movements of the head, neck and upper limbs

Question 16

Describe the rubrospinal tract

Answer 16

Originates in the red nucleus and decussates in the midbrain shortly after, travels with the lateral corticospinal tracts, ends at the cervical spinal cord level.

Flexor biased upper limbs

Question 17

What happens when the pyramidal system is immature of broken?

Answer 17

If the pyramidal system is damaged rubrospinal tract will take over and caused flexor biased of the arms

Question 18

What happens with UMN lesions ABOVE midbrain level

Answer 18

Removes corticocospinal input, thus rubrospinal overides

Flexor arms, extensor legs

Question 19

What happens with UMN lesions BELOW midbrain level

Answer 19

Removes rubro and corticospinal tracts

Extensor arms and legs