L17: Descending Pathways - B Flashcards
Pyramidal cells are examples of ___ whereas motor neurons in the ventral horn are examples of _____
UMN; LMN
Describe how the motor system is hierarchically organized:
In both the hierarchical and parallel organization of the motor system, ___ send movement command and ___ inform muscle
A. LMN; UMN
B. UMN; LMN
B. UMN; LMN
What are the five descending pathways?
1 - Corticospinal
2 - Rubrospinal
3 - Reticulospinal
4 - Tectospinal
5 - Vestibulospinal
Where do descending/corticofugal pathways ALWAYS originate from?
Cortex
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 ____
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
- Lateral corticospinal tract (LCST)
- Rubrospinal tract
___ pathways: Involves direct communication between UMN/LMN (motor nuclei of CN and motor neurons in ventral horn)
Direct pathways
____ 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)
Indirect; proper
Which corticofugal pathways are ipsilateral?
Corticostriate and Corticorubral
Which corticofugal pathways are bilateral?
Corticonuclear and corticoreticular
Which is the ONLY corticofugal pathway that is contralateral?
Corticospinal
Which two pathways make up the pyramidal system?
- Corticospinal tract
- Corticonuclear tract
True or False: The pyramidal system (corticospinal/nuclear tract) is bisynaptic, slow and interrupted, and responsible for involuntary fine movements
False -
1) monosynaptic
2) fast and interrupted
3) voluntary movements
True or False: The CST has pathways that end contralaterally and is responsible for voluntary fine movements
True
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
E. Primary motor
Which four brainstem levels do CST fibers course through?
- Crus cerebri
- Basal pons
- Pyramid of medulla
- Internal capsule
Where does most of the pyramidal decussation occur?
Most decussation occurs at lateral motor systems
Which part of the corticospinal tract controls innervation of distal musculature + complications in the area can cause muscle atrophy?
A. LCST
B. ACST
A. LCST
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
A. LCST
Which part of the coticospinal tract is located in the ventral funiculus and activates neurons that innervate contralateral proximal muscles?
A. ACST
B. LCST
A. ACST
All the fibers of the ACST terminal in the _____, of all spinal levels, and the fibers eventually decussate in _____
ventral horn; anterior white commisure
True or False: The CST is somatotopically organized
True
True or False: The corticonuclear tract controls voluntary fine movements, mostly unilateral
False - the corticonuclear tract controls voluntary fine movement, mostly BILATERAL
The Extrapyramidal System is mainly for ___ movements
A. involuntary
B. voluntary
A. involuntary
Which three tracts make up the Extrapyramidal System?
- Rubrospinal Tract
- Vestibulospinal Tract
- Reticulospinal Tract
True or False: The Extrapyramidal System is an indirect (multineuronal) pathway for control, adjustment, and synchronization of movement
True
Which of the following tracts belonging to the Extrapyramidal System influence flexor muscles?
A. Rubrospinal Tract
B. Vestibulospinal Tract
C. Reticulospinal Tract
A. Rubrospinal Tract
____ 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
A. Rubrospinal Tract
True or False: The rubrospinal tract may partially compensate for loss of CST in primates and ends contralaterally
True
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
B. Vestibulospinal Tract
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
C. Reticulospinal Tract
Which two pathways often exert opposite effect on extensor muscles for postural adjustments?
A. Rubrospinal Tract
B. Vestibulospinal Tract
C. Reticulospinal Tract
B. Vestibulospinal Tract
C. Reticulospinal Tract
Where does the tectospinal tract originate from?
Superior Colliculus
Where do the axons of the tectospinal tract decussate?
Midbrain tegmentum
Where do the fibers of the tectospinal tract terminate?
Ventral spinal cord (cervical level only!)
Which tract is important for reflex control and coordination of head, neck, and eyes in response to stimuli?
Tectospinal Tract
True or False: Motor info may also travel through complex + reverberating circuits receiving contribution from other structures (basal ganglia + cerebellum)
True
