Descending Pathways 2 (section 3) Flashcards
Activity of the LVST and MVST are important in support of the body against what?
Against Gravity
Maintenance of upright posture
What are the two vestibulospinal tracts?
Lateral Vestibulospinal tract (LVST)
Medial Vestibulospinal tract (MVST)
What is the ascending output from vestibular nuclei that aids in coordination of eye and head movements in the vestibulococular reflex
Medial Longitudianl fasciculus (MLF)
What cranial nerves does the medial longitudinal fasciculus associate with
CN III
CN IV
CN VI
Where do the cell bodies arise from in the Lateral vestibulospinal tract
Lateral vestibular nucleus (Deiter’s nucleus)
How does the Lateral Vestibulospinal tract descend?
Uncrossed
Function of Lateral Vestibulospinal tract
- Facilitate extensor alpha and gamma motor neurons of the Lower Extremities
- Flexors of the upper extremities
What is the primary antigravity pathway?
Lateral vestibulospinal tract (LVST)
Where do the cell bodies of the medial vestibulospinal tract arise from
Medial vestibular nucleus
Where do fibers of the Medial Vestibulospinal tract primarily terminate?
in the cervical and upper thoracic levels
Primary function of the MVST?
Inhibit upper extremity extensors
Facilitate Flexors
Cell bodies in Tectospinal tract arise where?
The Superior Colliculus of the midbrain tectum
Where does the Tectospinal tract run along with the medial vestibulospinal tract?
In the Upper Cervical spinal cord
What tract has fibers that terminate in the upper four cervical segments of the spinal cord
Tectospinal tract
Function of the Tectospinal tract
Mediate reflex postural movements of the head and neck in response to NOVEL visual stimuli
T or F, Muscles are supplied by only one ventral root
False, Muscles are supplied by SEVERAL ventral roots
Example (biceps = C5-C6)
Paresis
only one or two ventral roots are damaged
Paralysis
Results if all roots innervating a particular muscle are destroyed
Lesions above the C3 level can cause what type of problem?
Diaphragm can be denervated and leave the patient ventilator-dependent
S2, S3 and S4 innervate what structures?
Bladder and bowel control
Alpha motor neurons have what fiber diameter?
12-20 microns
Gamma motor neurons have what fiber diameter
2-10 microns
Alpha motor neurons have what conduction velocity
15-120 m/sec
Gamma motor neurons conduction velocity (m/sec)
10-45 m/sec
