Descending Pathways

Question 1

What are the two modes of motor control?

Answer 1

External and internal control

Question 2

What is external motor control?

Answer 2

Sensory guided control of movement

Question 3

Which parts of the brain are involved in external motor control?

Answer 3

Parietal cortex, premotor cortex, cerebellum

Question 4

What is internal motor control?

Answer 4

Non-sensory guided motor control

Question 5

Which parts of the brain are involved in internal motor control?

Answer 5

Prefrontal cortex, supplementary motor area, basal ganglia

Question 6

Where do the motor projection fibers that originate in the motor travel through to enter the spinal cord?

Answer 6

Through the corona radiata and the internal capsule

Question 7

What the axons that join cerebral hemispheres called?

Answer 7

Commissural fibres

Question 8

What are association fibres?

Answer 8

Axons that connect different parts of the same cerebral hemisphere

Question 9

What are motor projection fibres?

Answer 9

Axons that originate in the motor cortex and leave the cranium

Question 10

What are upper motor neurons?

Answer 10

Neurons where the cell body originates in the cerebral cortex or brain stem

Question 11

What are the characteristics of upper motor neurons?

Answer 11

Do not transmit impulses directly to the muscles

Glutamatergic

Question 12

What are lower motor neurons?

Answer 12

Motor neurons where the cell body originates in the anterior grey column of the spinal cord, the brainstem, or cranial nerve nuclei

Question 13

What are the characteristics of lower motor neurons?

Answer 13

Transmit impulses directly to muscles

Cholinergic

Question 14

Which type of motor neuron is a first order neuron in descending tracts?

Answer 14

Upper motor neurons

Question 15

Which type of motor neuron is a second order neuron in descending tracts?

Answer 15

Lower motor neurons

Question 16

What is the transduction of sensory fibres that results in muscular action without the input of the brain called?

Answer 16

Reflex arcs

Question 17

Where do pyramidal tracts synapse?

Answer 17

Cranial nerves or neurons in the anterior horn of spinal cord

Question 18

What do pyramidal tracts control in terms of movement?

Answer 18

Voluntary movement

Question 19

Where do most pyramidal tracts originate?

Answer 19

Motor cortex

Question 20

Do most pyramidal tracts decussate?

Answer 20

Yes

Question 21

What do extra-pyramidal tracts control in terms of movement?

Answer 21

Coordination of movement, posture control, muscle tone

Question 22

Where do most extra-pyramidal tracts originate?

Answer 22

Brain stem

Question 23

What are the two subtypes of pyramidal tracts?

Answer 23

Corticospinal or corticobulbar

Question 24

Where are most cell bodies of pyramidal tracts located?

Answer 24

Precentral gyrus - primary motor cortex

Question 25

Where do pyramidal tracts receive input from?

Answer 25

Supplementary motor area, premotor cortex fibres, parietal lobe, cingulate gyrus

Question 26

Where do corticospinal pyramidal tracts originate from?

Answer 26

Pyramidal neurons of layer 5 of cortex

Question 27

Where does the corticospinal tract receive input from?

Answer 27

Motor and pre-motor cortical areas

Question 28

Where does the corticospinal tract travel through on its way to the spinal cord?

Answer 28

From cerebral cortex to the internal capsule to the cerebral peduncles to the medullary pyramids

Question 29

What are the two divisions of corticospinal tracts?

Answer 29

Anterior corticospinal Lateral corticospinal

Question 30

What do anterior corticospinal tracts control in terms of movement?

Answer 30

Postural control in central axial and proximal muscles

Question 31

What do lateral corticospinal tracts control in terms of movement?

Answer 31

Fine movement of ispilateral limbs via control of appendicular muscles

Question 32

Where do anterior corticospinal tracts decussate?

Answer 32

Spinal cord

Question 33

Where do lateral corticospinal tracts decussate?

Answer 33

Medullary pyramids

Question 34

How do corticobulbar pyramidal tracts differ from corticospinal tracts?

Answer 34

Initially follows same pathway but synapses with motor nuclei of cranial nerves in upper pons Some fibres decussate and others do not

Question 35

What do corticobulbar pyramidal tracts control in terms of movement?

Answer 35

Voluntary muscle movement in face

Question 36

What are the four extrapyramidal tracts?

Answer 36

Vestibulospinal Reticulospinal Rubrospinal Tectospinal

Question 37

What function are the extrapyramidal tracts involved in, in terms of movement?

Answer 37

Involuntary and automatic control of movements, posture, and muscle tone, gross motor movements

Question 38

What symptoms are associated with an upper motor neuron lesion?

Answer 38

Spastic paralysis, hypertonia

Question 39

What symptoms are associated with a lower motor neuron lesion?

Answer 39

Flaccid paralysis, hypotonia, muscle atrophy, loss of reflexes

Question 40

A lesion on which nuclei cause bulbar palsy?

Answer 40

Glossopharyngeal or vagus nuclei Hypoglossal nuclei

Question 41

A lesion on which nerve causes Bell's palsy?

Answer 41

Lower motor neuron lesion of the facial nerve