The structure and function of the descending tract Part 2

Question 1

Where do the tracts run to that have control of the limb muscles

Answer 1

Extends for several segments
Distal part of the ventral horn
Cervical and lumbosacral
Distal part of the limb

Question 2

Where do the lower motor neurons reside?

Answer 2

Ventral horn of the spinal cord

Question 3

Lower motor neurons that innervates the axial musculature reside where in the spinal cord?

Answer 3

Medial part of the ventral horn

Question 4

Lower motor neurons that innervates the limb muscles reside where in the spinal cord?

Answer 4

Lateral part the ventral horn- distal limb muscles

Medial part of ventral horn- proximal muscles

Question 5

Where do the upper motor neurons reside for the limb muscle neurons and how do they connect to the lower motor neurons

Answer 5

Lateral motor systems

synapse onto the lateral portion of the ventral horn

Question 6

Why is it important for the column/ tract to extend for several segments?

Answer 6

Enable movement for different muscles that connect the same limb

Question 7

Where do the upper motor neurons reside for the axial musculature neurons and how do they connect to the lower motor neurons

Answer 7

Medial motor systems

Question 8

How is posture and balance maintained

Answer 8

Interneurons enable bilateral innervation of both sides of the body

Question 9

What are the major groups of the descending major pathways

Answer 9

Lateral pathways

Medial pathways

Question 10

What are the tracts in the lateral pathways

Answer 10

Lateral corticospinal tract
Lateral rubrospinal
reticulospinal tract

Question 11

What are the tracts in the medial pathways

Answer 11

Anterior corticospinal tract
Tectospinal tract
Medial reticulospinal tract
Lateral vestibulospinal tract 
Medial vestibulospinal tract

Question 12

What do the Lateral pathways control?

Answer 12

Control proximal and distal muscles

responsible for most voluntary movements of arms and legs

Question 13

What do the medial pathways control?

Answer 13

Control axial muscles

control anti-gravity muscles

Question 14

What is the function of the corticospinal tract?

Answer 14

Controls muscles of distal limbs and trunk

Essential for fine motor movements

Question 15

What is the corticospinal tract also known as? Why?

Answer 15

Pyramidal tract

Forms medullary pyramids

Question 16

What is structrally special about corticopsinal tract?

Answer 16

Longest and largest descending tract

Question 17

Where from and to does the corticospinal tract go?

Answer 17

Motor cortex to spinal cord

Question 18

What happens to neurons at a point in the corticospinal tract

Answer 18

Decussation at medulla-spinal cord junction

Question 19

What percentage of the corticospinal tract is decussated?

Answer 19

85%

Question 20

What are the decussated regions of the corticospinal tract called?

Answer 20

Lateral corticospinal

Question 21

What is the undecussated regions of the corticospinal tract known as and called?

Answer 21

Ipsilateral

Anterior corticospinal tract

Question 22

What is the function of the lateral corticospinal tract?

Answer 22

Controls muscles of distal limbs

Responsible for most voluntary
movements of arms and legs

Fine movernent of contralateral limbs

Question 23

What is the function of the anterior corticospinal tract?

Answer 23

Controls trunk muscles

Responsible for maintaining posture

Question 24

What does the lateral corticospinal tract innervate?

Answer 24

Lateral lower neurons

Question 25

What does the anterior corticospinal tract innervate?

Answer 25

Anterior lower neurons

Question 26

Where does the decussation take place for the lateral corticospinal tract? What does this allow

Answer 26

medulla | It do to its function

Question 27

Where does the decussation take place for the anterior corticospinal tract? What does this allow

Answer 27

At the spinal cord provide contralateral innervation but also ipsilateral innovation enable bilateral control

Question 28

Where to and from does the corticonuclear tract go?

Answer 28

Motor cortex to brain stem nuclei

Question 29

What does the corticonuclear tract innervate?

Answer 29

Cranial nerves

Question 30

Which nuclei do not receive bilateral innervation from cortex

Answer 30

facial motor nucleus | hypoglossal nucleus

Question 31

What are the extrapyramidal pathways?

Answer 31

Rubrospinal tract Vestibulospinal tract Tectospinal tract

Question 32

Where does the rubrospinal tract originate in

Answer 32

Red nucleus (brainstem)

Question 33

Where does the Vestibulospinal tract originate in

Answer 33

Vestibular nucleus

Question 34

Where does the Tectospinal tract originate in

Answer 34

Superior colliculus in midbrain

Question 35

What is the function of the vestibulospinal tract and what does this do?

Answer 35

Controls muscles of neck, trunk and some leg muscles | Maintains upright posture and head stabilisation

Question 36

What does the testospinal tract innervate

Answer 36

Innervate contralateral motor neurons controlling head position

Question 37

What is the function of the rubrospinal tract

Answer 37

Responsible for regulation of flexor muscles (upper limb flexion)

Question 38

How do sizes of the rubrospinal tract vary in organisms?

Answer 38

Small in humans, larger in other animals (lateral pathway)

Question 39

Where does the reticulospinal tract originate from

Answer 39

Reticular formation (pons and medulla)

Question 40

What does the reticulospinal tract innervate

Answer 40

Innervate interneurons affecting corticospinal tract

Question 41

What are the types of reticulospinal tract

Answer 41

Medullary reticulospinal tract | Pontine reticulospinal tract

Question 42

What is the innervation of the medullary reticulospinal tract

Answer 42

Bilateral innervation of flexor motor neurons

Question 43

What is the innervation of the pontine reticulospinal tract

Answer 43

Ipsilateral innervation of extensor motor neurons

Question 44

What can damage to the reticulospinal tract lead to?

Answer 44

Spasticity continuos contractions

Question 45

What is the rubrospinal tract's role in animals

Answer 45

predominant lateral spinal pathway

Question 46

Where does the tectospinal tract take its sensory information from?

Answer 46

eyes and visual cortex

Question 47

What does the tectospinal tract do?

Answer 47

enables us to coordinate eye and head movement together with maintaining posture through voluntary movement but also in response to visual and auditory stimuli as part of the tectospinal reflex

Question 48

What is the role of the reticulospinal tracts

Answer 48

regulating breathing and heart rate and alertness as well as movement aid posture influence muscle tone Modulates voluntary movements, aids locomotion