Upper motor neurons

Question 1

What does the medial group control?

Answer 1

Axial and girdle musculature, so:

• posture
• locomotion
• proximal components of reaching movements

Question 2

What are the medial tracts?

Answer 2

reticulospinal
tectospinal
vestibulospinal
ventral corticospinal

Question 3

What is the lateral group made up of?

Answer 3

rubrospinal

lateral corticospinal

Question 4

What does the lateral group control?

Answer 4

limb movement

involved in precision grip and palpation

Question 5

Draw the descending tracts

Answer 5

OneNote

Question 6

Mnemonic for descending tracts

Answer 6

Cleopatra May Think Provided Vain Monks Riot Calmly.

• anterior Corticospinal
• Medial longitudinal fasciculus (includes the medial vestibulospinal)
• Tectospinal
• Pontine reticulospinal
• lateral Vestibulospinal
• Medullary reticulospinal
• Rubrospinal
• lateral Corticospinal

Question 7

What is another name for pyramidal tracts?

Answer 7

Corticospinal

Question 8

What is another name for extrapyramidal tracts?

Answer 8

Extra-corticospinal

Question 9

Describe briefly the pyramidal tracts

Answer 9

• originate in the cerebral cortex
• carry motor fibres to the spinal cord and brainstem
• responsible for the voluntary control of the musculature of the body and face

Question 10

Describe briefly the extrapyramidal tracts

Answer 10

• Originate in the brain stem
• Carry motor fibres to the spinal cord
• Responsible for involuntary and automatic control of musculature (such as muscle tone, balance, posture and locomotion

Question 11

Do the cerebellum and basal ganglia send projections down into the spinal cord?

Answer 11

No, they send neurons which modulate the descending information

Question 12

Where do the pontine and medullary reticulospinal tracts originate?

Answer 12

In the pontine and medullary reticular formations respectively in the

Question 13

Describe pontine reticulospinal tract

Answer 13

• travels ipsilaterally in the ventral funiculus
• enhances the antigravity reflexes of the spinal cord, facilitates AXIAL AND PROXIMAL EXTENSORS OF THE LOWER LIMB and maintains a standing posture

Question 14

Describe the medullary tract

Answer 14

• projects contralaterally in the anterolateral funiculus
• liberates the anti-gravity muscles from reflex control - inhibits reflexes
• FLEXOR MUSCLES

Question 15

What is the reticular formation?

Answer 15

• series of interconnected nuclei in brainstem from upper midbrain to lower medulla

Question 16

Input to pontoreticulospinal

Answer 16

No cerebral cortex

Ascending pathways

Question 17

Input to medullary reticulospinal

Answer 17

Cerebral cortex - corticoreticular fibres

Ascending tracts

Question 18

What does the vestibulospinal tract comprise?

Answer 18

Lateral and medial branches

Question 19

Where does the vestibulospinal tract originate?

Answer 19

Vestibular nuclei of the medulla

• the medial tract originates in the medial vestibular nucleus (Schwalbe’s nucleus)
• the lateral tract originates in the lateral vestibular nucelus (Deiter’s nucleus)

Question 20

What do the vestibular nuclei receive input from? What do these signal?

Answer 20

The semicircular canals and otolith organs of the inner ear

• Head position and movement via the auditory nerve
• also receive input from the cerebellum (fastigial nucleus w/proprioceptive information)

Question 21

How do the vestibulospinal tracts travel?

Answer 21

• both ipsilaterally in the ventral funiculus
• smaller medial tract innervates axial muscles in the cervical region controlling neck movements
• the larger lateral tract descends as far as the lumbar spinal cord → fascilitates antigravity (EXTENSOR) motor neurones, especially axial ones, and helps to maintain posture by controlling postural muscles (e.g. the hip, back and shoulder muscles)

Question 22

Which tracts do extensor muscles?

Answer 22

Vestibulospinal tract

Ponto-reticulospinal tract

Question 23

Which tracts to flexor muscles?

Answer 23

Rubrospinal tract

Medullo-reticulospinal tract

Question 24

Where does the superior colliculus receive input from?

Answer 24

• retina

- also somatosensory and auditory inputs

Question 25

Where does the superior colliculus receive input from?

Answer 25

- retina | - also somatosensory and auditory inputs

Question 26

Where does the tectospinal tract end? What does it innervate?

Answer 26

At the cervical level | Muscles of the neck, shoulder and upper trunk

Question 27

Main functions of the tectospinal tract

Answer 27

Coordinating head and neck movement | Mediating gaze

Question 28

Where does the superior colliculus receive input from?

Answer 28

- retina | - also somatosensory and auditory inputs

Question 29

Where does the tectospinal tract end? What does it innervate?

Answer 29

At the cervical level | Muscles of the neck, shoulder and upper trunk

Question 30

Where does the rubrospinal tract terminate? What does it do?

Answer 30

Cervical spinal levels Arm movements Biased towards flexion movements End on interneurons

Question 31

Where does the rubrospinal tract originate?

Answer 31

Red nucleus of the midbrain, primarily from the caudal magnocellular part

Question 32

Where does the rubrospinal pathway decussate?

Answer 32

Midbrain - ventral tegmental decussation

Question 33

What are the two corticospinal tracts?

Answer 33

Ventral and lateral

Question 34

Where does the rubrospinal pathway decussate?

Answer 34

Midbrain - ventral tegmental decussation

Question 35

Where is the primary motor cortex?

Answer 35

In the precentral gyrus

Question 36

What is on either side of the medullary pyramid?

Answer 36

Medullary olives

Question 37

Where is the primary motor cortex?

Answer 37

In the precentral. gyrus

Question 38

What is on either side of the medullary pyramid?

Answer 38

Medullary olives

Question 39

Where do the corticospinal tract decussate? What percentage decussate?

Answer 39

At the medullary pyramids - 80%

Question 40

What happens to the corticospinal fibres that decussate at the medullary pyramids?

Answer 40

They go into the lateral columns and become the lateral corticospinal tracts

Question 41

What happens to the corticospinal fibres that DON'T decussate at the medullary pyramids?

Answer 41

Goes down the anterior white column Becomes the ventral cortispinal tract Cross over to the opposite ventral grey horn to stimulate lower motor neurones

Question 42

What is the lateral corticospinal tract associated with?

Answer 42

Distal limb musculature | Fine and precise movements

Question 43

What is the anterior corticospinal tract associated with?

Answer 43

Axial musculature | Gross/large movements

Question 44

Path of ventral corticospinal tract

Answer 44

``` Internal capsule Crus cerebri Pons Pyramid Ipsilateral ventral funiculus ```

Question 45

Path of lateral corticospinal tract

Answer 45

``` Internal capsule Crus cerebri Pons Pyramid Contralaterally in the lateral funiculus ```

Question 46

What does the supplementary motor area do?

Answer 46

Relays inputs from the basal ganglia via the thalamic ventral anterior nucleus Also receive input from the prefrontal lobe and is important in internally-generated movements

Question 47

What is Brown Sequard syndrome?

Answer 47

lateral hemisection of the spinal cord where there is: - loss of pain and temperature contralaterally due to the decussation of nociceptive inputs in the spinal cord - sensory loss ipsilaterally due to the lack of decussation - motor impairment ipsilaterally due to decussation at higher points of the majority of motor input to the descending tracts

Question 48

What is anterior cord syndrome?

Answer 48

- lesion in anterior portion of the spinal cord - dorsal column is left intact (retains proprioception and vibratory sensation) - motor and nociceptive function is lost due to entire lesion bilaterally of both anterior segments of the spinal cord

Question 49

Draw a section of the spinal cord - ascending and descending tracts

Answer 49

OneNote

Question 50

What is anterior cord syndrome?

Answer 50

- lesion in anterior portion of the spinal cord where the dorsal column is left intact, but complete motor and nociceptive function is lost due to entire lesion bilaterally of both anterior segments of the spinal cord

Question 51

Compare LMN and UMN lesions

Answer 51

``` LMN - everything is downregulated: - flaccid - less muscle contraction - hypotonic - less muscle tone - hyporeflexic - less muscle reflexes - denervation atrophy - less muscle innervation - Babinski negative - toes point down UMN - everything upregulated: - Spastic - more - Hypertonic - more - Hyperreflexic - more - Disuse atrophy - more - Babinski positive - toes point up ```

Question 52

What is central cord syndrome?

Answer 52

- loss of nociceptive fibres bilaterally due to effect of decussation - impairment of function of nerves that mediated tendon reflexes - size of lesion determines subsequent effects - greater motor loss in upper limbs than lower limbs

Question 53

Compare LMN and UMN lesions

Answer 53

``` LMN - everything is downregulated: - flaccid - less muscle contraction - hypotonic - less muscle tone - hyporeflexic - less muscle reflexes - denervation atrophy - less muscle innervation - Babinski negative - toes point down UMN - everything upregulated: - Spastic - more - Hypertonic - more - Hyperreflexic - more - Disuse atrophy - more - Babinski positive - toes point up ```