Descending Motor Pathways Part II Flashcards
What part of the internal capsule does motor go through
The posterior limb
What does genu mean
Bend
What limb of the internal capsule is the corticospinal tract in
Posterior limb
Where does the lateral corticospinal tract travel
Posterior limb of internal capsule to cerebral peduncles through the pons to the pyramids
Where does the lateral corticospinal tract decussate/cross
Cervicomedullary junction
What percent of the corticospinal tract decussate at the cervicomedullary junction
85%
True or False:
The lateral corticospinal tract decussates while the anterior corticospinal tract does not decussate in the medulla
True
Where does the rubrospinal tract originate
Red nucleus of the midbrain
What does the rubrospinal tract receive afferent input from (2)
- Ipsilateral cortical motor areas (corticorubral pathway)
2. Contralateral side of the cerebellum
True or False:
The fibers of the rubrospinal tract decussate immediately after they emerge
True
Where does the rubrospinal tract decussate
Ventral tegmental decussation
True or False:
The rubrospinal tract fibers descend with the corticospinal tract after they decussate
True
Where does the rubrospinal tract terminate in humans
Cervical enlargement
True or False:
In monkeys the rubrospinal tract can compensate for corticospinal lesions
True
What happened to the monkey when you severed the lateral corticospinal tract
Function of fingers was lost but recovered rather quickly
What recovered the ability to use the fingers again
The rubrospinal tract compensated
Was the rubrospinal tract able to recover the ability to use individual fingers
Nope
If the rubrospinal tract was also severed could the monkey recover use of hands and fingers
Negative
What does the anterior corticospinal tract consist of
The corticospinal fibers that did not decussate in the rostral medulla
Where do the anterior corticospinal tract fibers decussate
In the spinal cord near the synapse of the LMN in the central gray
What does the anterior corticospinal tract supply (3)
- Neck
- Bilateral upper girdle
- Axial muscles
What does the vestibular system provide
Rapid sensory indication of the rotation and linear movement of the head
Where does the vestibular apparatus send signals
To the vestibular nuclei in the dorsal surface of the medulla via cranial nerve VIII
What are the 4 vestibular nuclei that receive distinct but overlapping info
- Superior
- Medial
- Lateral
- Inferior
Where do axons of the vestibular nuclei terminate on or near
Motor neurons for muscles of the legs, eyes, and neck
Where does the medial vestibulospinal tract originate
Medial vestibular nucleus
Where does the medial vestibulospinal tract descend
Bilaterally to cervical levels of the cord
Where does the lateral vestibulospinal tract originate
Lateral, inferior, and superior to vestibular nuclei
Where does the lateral vestibulospinal tract receive input from
Vestibulocerebellum
What does the vestibulocerebellum modulae
Postural adjustments
Where does the lateral vestibulospinal tract descend
Ipsilaterally to all levels of the cord
What do both the medial and lateral vestibulospinal tracts control
Proximal muscles
What does the lateral vestibulospinal tract cause to happen when you tip forward in raft
Stimulates extensor motor neurons in LE to adjust limbs and trunk musculature
Where does the reticulospinal tract terminate
The entire cord
What is the reticulospinal tract involved in
Automatic and anticipatory posturing and gait movements
What are the 2 tracts of the reticulospinal tract
- Medullary (lateral)
2. Pontine (medial)
What does the medullary tract off the reticulospinal tract do (3)
- Inhibits extensors and excites flexors
- Inhibits voluntary movements
- Reduces tone
What does the pontine tract of the reticulospinal tract do (3)
- Excites extensors and inhibits flexors
- Facilitates voluntary movements
- Increases tone
True or False:
Since we have feed forward processing we are able to predict changes in posture and generate an appropriate stabilizing response
True
What is an example of the stabilizing response
The gastrocnemius fires when doing a biceps curl to prevent you from pulling yourself into the machine.
What happened to cats if you inhibited the reticulospinal tract
Paw still moved but other legs do not
Where does the tectospinal tract originate
Superior colliculus
Where is the superior colliculus located
Tectum of the midbrain
Where does the tectospinal tract decussate
Immediately in the midbrain
Where does the tectospinal tract terminate
Largely in the upper cervical cord
What does the tectospinal tract do
Coordinates head movements in response to rapid eye movements
What does the tectospinal tract receive input from (2)
- Hearing
2. Eyes
Is the tectum anterior or posterior on the midbrain
Posterior
Is the tegmentum anterior or posterior on the midbrain
Anterior
True or False:
The function of the tectospinal tract is very well understood in humans
False
