L17: Descending Pathways - B

Question 1

Pyramidal cells are examples of ___ whereas motor neurons in the ventral horn are examples of _____

Answer 1

UMN; LMN

Question 2

Describe how the motor system is hierarchically organized:

Answer 2

Question 3

In both the hierarchical and parallel organization of the motor system, ___ send movement command and ___ inform muscle
A. LMN; UMN
B. UMN; LMN

Answer 3

B. UMN; LMN

Question 4

What are the five descending pathways?

Answer 4

1 - Corticospinal
2 - Rubrospinal
3 - Reticulospinal

4 - Tectospinal
5 - Vestibulospinal

Question 5

Where do descending/corticofugal pathways ALWAYS originate from?

Answer 5

Cortex

Question 6

If a message goes from cortex to brain stem, as a direct pathway, it is known as ____

If a message goes from cortex to spinal cord, as a direct pathway, it is known as ____

Answer 6

Question 7

Which of the following descending pathways are part of the Lateral Group?
A. Corticospinal
1. LCST
2. ACST

B. Rubrospinal

C. Reticulospinal
1. LRST
2. MRST

D. Vestibulospinal
E. Tectispinal

Answer 7

1. Lateral corticospinal tract (LCST)
2. Rubrospinal tract

Question 8

___ pathways: Involves direct communication between UMN/LMN (motor nuclei of CN and motor neurons in ventral horn)

Answer 8

Direct pathways

Question 9

____ pathways: Involves indirect communication to the LMN via intermediate stop in a ___ nucleus in the brain stem. This system receives other contribute from intermediate player (e.g cerebellum)

Answer 9

Indirect; proper

Answer 10

Question 11

Answer 11

Question 12

Which corticofugal pathways are ipsilateral?

Answer 12

Corticostriate and Corticorubral

Question 13

Which corticofugal pathways are bilateral?

Answer 13

Corticonuclear and corticoreticular

Question 14

Which is the ONLY corticofugal pathway that is contralateral?

Answer 14

Corticospinal

Question 15

Which two pathways make up the pyramidal system?

Answer 15

1. Corticospinal tract
2. Corticonuclear tract

Question 16

True or False: The pyramidal system (corticospinal/nuclear tract) is bisynaptic, slow and interrupted, and responsible for involuntary fine movements

Answer 16

False -
1) monosynaptic
2) fast and interrupted
3) voluntary movements

Question 17

True or False: The CST has pathways that end contralaterally and is responsible for voluntary fine movements

Answer 17

True

Question 18

Although the corticospinal fibers originate from multiple cortical areas, which is the major contributor?
A. Somatosensory association (parietal motor area)
B. Primary somatosensory
C. Supplemental motor
D. Premotor
E. Primary motor

Answer 18

E. Primary motor

Question 19

Which four brainstem levels do CST fibers course through?

Answer 19

1. Crus cerebri
2. Basal pons
3. Pyramid of medulla
4. Internal capsule

Question 20

Answer 20

Question 21

Answer 21

Question 22

Where does most of the pyramidal decussation occur?

Answer 22

Most decussation occurs at lateral motor systems

Question 23

Which part of the corticospinal tract controls innervation of distal musculature + complications in the area can cause muscle atrophy?

A. LCST
B. ACST

Answer 23

A. LCST

Question 24

Which part of the corticospinal tract is located in the lateral funiculus and projects to/terminates in all levels of the ventral spinal cord. It also controls muscles of CONTRALATERAL hand, finger, foot, toes

A. LCST
B. ACST

Answer 24

A. LCST

Question 25

Which part of the coticospinal tract is located in the ventral funiculus and activates neurons that innervate contralateral proximal muscles? A. ACST B. LCST

Answer 25

A. ACST

Question 26

All the fibers of the ACST terminal in the _____, of all spinal levels, and the fibers eventually decussate in _____

Answer 26

ventral horn; anterior white commisure

Question 27

True or False: The CST is somatotopically organized

Answer 27

True

Question 28

True or False: The corticonuclear tract controls voluntary fine movements, mostly unilateral

Answer 28

False - the corticonuclear tract controls voluntary fine movement, mostly BILATERAL

Question 29

The Extrapyramidal System is mainly for ___ movements A. involuntary B. voluntary

Answer 29

A. involuntary

Question 30

Which three tracts make up the Extrapyramidal System?

Answer 30

1. Rubrospinal Tract 2. Vestibulospinal Tract 3. Reticulospinal Tract

Question 31

True or False: The Extrapyramidal System is an indirect (multineuronal) pathway for control, adjustment, and synchronization of movement

Answer 31

True

Question 32

Which of the following tracts belonging to the Extrapyramidal System influence flexor muscles? A. Rubrospinal Tract B. Vestibulospinal Tract C. Reticulospinal Tract

Answer 32

A. Rubrospinal Tract

Question 33

____ have fibers that arise from red nucleus in midbrain and its fibers decussate in midbrain and course in lateral funiculus A. Rubrospinal Tract B. Vestibulospinal Tract C. Reticulospinal Tract

Answer 33

A. Rubrospinal Tract

Question 34

True or False: The rubrospinal tract may partially compensate for loss of CST in primates and ends contralaterally

Answer 34

True

Question 35

Which of the following modulates postural adjustments in response to vestibular stimuli and influences EXTENSOR muscles? A. Rubrospinal Tract B. Vestibulospinal Tract C. Reticulospinal Tract

Answer 35

B. Vestibulospinal Tract

Question 36

Which tract arises from the reticular formation, and both of its tracts (LRST and MRST) modulate UNVOLUNTARY movements for EXTENSOR muscles? A. Rubrospinal Tract B. Vestibulospinal Tract C. Reticulospinal Tract

Answer 36

C. Reticulospinal Tract

Question 37

Which two pathways often exert opposite effect on extensor muscles for postural adjustments? A. Rubrospinal Tract B. Vestibulospinal Tract C. Reticulospinal Tract

Answer 37

B. Vestibulospinal Tract C. Reticulospinal Tract

Question 38

Where does the tectospinal tract originate from?

Answer 38

Superior Colliculus

Question 39

Where do the axons of the tectospinal tract decussate?

Answer 39

Midbrain tegmentum

Question 40

Where do the fibers of the tectospinal tract terminate?

Answer 40

Ventral spinal cord (cervical level only!)

Question 41

Which tract is important for reflex control and coordination of head, neck, and eyes in response to stimuli?

Answer 41

Tectospinal Tract

Question 42

True or False: Motor info may also travel through complex + reverberating circuits receiving contribution from other structures (basal ganglia + cerebellum)

Answer 42

True