MD4001 > Descending Pathways > Flashcards

Descending Pathways Flashcards

(49 cards)

Study These Flashcards
1
Q

What are the classes of movement?

A

• Voluntary:

  • complex actions e.g. reading and writing
  • purposeful, goal directed
  • learned
  • Reflexes
  • Rhythmic motor patterns
  • combines voluntary and reflexive acts
  • initiation and termination is voluntary
  • once initiated, repetitive and reflexive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the functions of motor control systems?

A
  • Posture and balance
  • Goal directed movements
  • Communication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What areas of the brain give rise to descending tracts?

A 
• Corticospinal tract from cerebral cortex
From brainstem and medulla:
• Reticulospinal 
• Vestibulospinal 
• Rubrospinal 
• Tectospinal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where does the corticospinal tract originate?

A

2/3 originate in the motor cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where do the fibres of the corticospinal tract cross?

A
  • Lateral corticospinal crosses at the medulla (pyramidal decussation)
  • Anterior corticospinal remains ipsilaterally to cervical and upper thoracic segments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of the lateral corticospinal tract

A
  • Runs the length of the spinal cord

* Control voluntary fine movements of distal muscles, particularly flexors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of the anterior corticospinal tract?

A

Control axial muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does Jacksonian epilepsy highlight?

A
  • Twitching begins at the extremities then movement of the hand and then of the arm
  • Reflects the spread of excitation over the cortex from epileptic focus
  • Shows the somatotropic arrangement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the difference in which muscles can be controlled by the primary and secondary motor cortices?

A
  • Primary controls muscles of opposite side of the body

* Secondary controls muscles on both sides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where does the rubrospinal tract originate?

A

In the red nucleus in the midbrain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where do the fibres of the rubrospinal tract cross?

A

Midbrain - ventral tegmental decussation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where do the fibres of the rubrospinal tract terminate?

A

On interneurones of ventral (motor) horn in the contralateral spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the function of the rubrospinal tract?

A

Facilitates flexor motor neurones and inhibits extensor motor muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where does the tectospinal tract originate?

A

In the superior colliculus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where do the fibres in the tectospinal tract terminate?

A

In interneurones in the contralateral cervical region of the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the function of the tectospinal tract?

A

Controls head movements in response to visual and auditory input

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where does the vestibulospinal tract originate?

A

In vestibular nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What inputs does the vestibulospinal tract receive?

A
  • Inhibitory input from the cerebellum

* Excitatory from the vestibular apparatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Lateral vestibulospinal tract

A
  • Fibres don’t cross, terminate on interneurones in ipsilateral spinal cord
  • Control extensor muscle motor tone of the proximal limbs
  • Maintenance of erect posture
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Medial vestibulospinal tract

Study These Flashcards
A
  • Bilateral
  • Terminate on interneurones in the cervical region
  • control the neck muscles
  • Keep head upright when body moves
21
Q

Where does the reticulospinal tract originate?

Study These Flashcards
A

Pontine reticular formation

22
Q

Where do the fibres of the reticulospinal tract terminate?

Study These Flashcards
A

Largely uncrossed, terminate on interneurons within the spinal cord

23
Q

What is the function of the reticulospinal tract?

Study These Flashcards
A

Control muscles of the trunk and proximal limbs
• Medullary (lateral) tracts inhibit extensor spinal reflex activity and facilitates flexor activity
• Medial (pontine) tracts facilitate
• Maintenance of posture and startle reactions

24
Q

What may be caused by damage to the reticulospinal tract?

25
Muscle motor pathway lesion
* Myositis, muscular dystrophy * Normal reflexes * Weakness/ wasting
26
Neuomuscular junciton motor pathway lesion
* Myasthenia gravis * Fatigueable weakness * Normal reflexes * Normal muscle bulk
27
Motor neurone motor pathway lesion
* UMN: CVA, spinal cord trauma | * LMN: motor neurone disease, neuropathy
28
Cerebellum motor pathway lesion
* Incoordinaiton, multiple sclerosis * Normal reflexes and strength * Slight change in tone
29
Basal ganglia motor pathway leison
* Parkinsons, Huntington's | * Movement changes
30
Describe upper motor neurones
* Cell bodies are in the brain or brainstem and do not project outside of the CNS * orchestrate complex directed movements
31
Describe lower motor neurones
* Cell bodies are in the brainstem or spinal cord and project outside the CNS to muscle * Single muscle innervation, cell bodies in the ventral horn of the spinal cord or motor nuclei of the brainstem
32
Muscle bulk in UMN vs LMN lesion
* UMN - normal | * LMN - decreased
33
Reflexes in UMN lesion vs LMN lesion
* UMN - increased | * LMN- absent
34
Tone in UMN lesion vs LMN lesion
* UMN - increased | * LMN - decreased
35
Power in UMN lesion vs LMN lesion
* UMN - Reduced extensors in arm, flexors in leg | * LMN - decreased
36
Co-ordination in UMN vs LMN lesion
* UMN - normal | * LMN - normal
37
Plantar response in UMN lesion vs LMN lesion
* UMN - extensor (normal is a flexed response) | * LMN - absent if leg/foot involved in lesion
38
What is a normal plantar response - Babinski
Toes go down (flexion)
39
Lamina I-VI
Terminations for primary afferent sensory neurones and neurones of reflex circuits
40
Lamina VI
Sensory input from joints and muscles
41
Lamina VII and IX
Cell bodies of motor neurones
42
Describe the location of motor neurones supplying the trunk vs those supplying distal muscles
* Those supplying the trunk are situated medially | * Those supplying the distal muscles are situated laterally
43
Describe the location of motor neurones that flex the limbs vs those that extend the limbs
Motor neurones that flex the limbs lie dorsal to those that extend the limbs
44
What are Renshaw cells and what do they do?
* Interneurones | * Suppresses weakly firing motor neurones and dampens strongly firing ones to produce economical movement
45
What reflects the importance of Renshaw cells?
* Strychnine poisoning * Disables Renshaw cells * Leads to convulsions
46
Describe the Myotatic reflex (knee jerk)
* Monosynaptic stretch reflex * Tap of the patellar tenon stretches the quadriceps muscle * Stimualtes nuclear bag receptors of the muscle spindle * Increases the rate of firing of group IA afferent fibres leading to the contraction of the quadriceps muscle * The IA fibres also stimulate inhibitory interneurones which inhibit antagonistic (flexor) muscles of the knee joint
47
When is the knee jerk reflex lost?
If there is damage to the lower lumbar dorsal roots of the spinal cord
48
What is the step cycle
• Stance phase: - foot touching the ground, flexion of the knee and ankle - finishes with extension about all joints for forward movement • Swing phase: - bending (flexion) of hip, knee and ankle followed by knee and ankle straightening (extension) • Alternates between the swing and stance phase
49
What is the central pattern generator
* Located in the spinal cord * Capable of autonomous signals * Modulated by proprioception input * Thought to be initiated by mesencephalic locomotor region - output thought to be through reticular nuclei and reticulospinal tracts
MD4001
flashcards
Decks in class (28)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions