Neuro - Motor Control 2
The medial dorsal horn has lower motor neurons that innervate ___ (proximal/distal) muscles
proximal
The lateral ventral horn contains lower motor neurons that mediate the expression of skilled voluntary movements of the ______ (proximal/distal) extremities
distal
True or False: The medial ventral horn contains lower motor neurons that govern posture, balance, locomotion, and orienting movements of the head and neck during shifts of visual gaze
true
Medial motor neurons that govern posture, balance, locomotion, and orienting movements of the head and neck during visual gaze receive descending input from pathways that originate mainly in the ______
brainstem
True or False: There is somatotopic organization of the ventral horn
true
Lateral motor neurons that mediate the expression of skilled voluntary movements of the distal extremities receive a major descending projection from the ____ via the main (lateral) division of the corticospinal tract
contralateral motor cortex
Upper motor neurons in the primary motor cortex send an axon downward to cross over at the medullary _____
pyramids
Neurons in the motor cortex give rise to axons that travel through the ______ (2 words) and combine on the ventral surface of the midbrain, within the cerebral peduncle
internal capsule
True or False: Pyramidal decussation explains why the right half of our brain controls the left side of our body and vice versa
true
If you lesion both cortical spinal tracts, but the ventormedial system remained intact, which would you expect?
Unable to make fractionated movements but posture would remain normal
The 2 subdivisions of the vestibulospinal tract are:
lateral; medial
The 2 subdivisions of the reticulospinal tract are:
pontine; medullary
The tectospinal tract originates in the _____ of the midbrain
superior colliculus
True or False: After leaving the colliculus, axons of the tectospinal tract quickly decussate and project close to the midline into cervical regions of the spinal cord, where they help to control muscles of the neck, upper trunk, and shoulders
true
The reticulospinal tracts arise mainly from the _____ of the brain stem
reticular formation
The pontine reticulospinal tract is ____, and the medullary reticulospinal tract is ____
medial; lateral
Which tract liberates the antigravity muscles from reflex control?
medullary reticulospinal tract
Which tract enhances the antigravity reflexes of the spinal cord, helping to maintain standing posture?
pontine reticulospinal tract
True or False: The vestibulospinal AND tectospinal tracts function to keep the head balanced as our body moves and to turn our heads in response to new sensory stimuli
true
The vestibulospinal tracts originate in the ____ of the medulla
vestibular nuclei
Which of the following apply to the medial vestibulospinal tracts?
projects bilaterally
activates cervical spinal circuits
guides head movements
Which of the following apply to the lateral vestibulospinal tracts?
projects ipsilaterally
activates lumbar circuits
maintains posture
True or False: There are feedforward and feedback mechanisms of postural control
true
Neurons in the motor cortex that supply the lateral part of the ventral horn to initiate movements of the distal limbs also terminate on neurons in the _____ to mediate postural adjustments that support the movement
reticular formation
True or false: The crossed-extensor reflex involves the ipsilateral flexor muscle’s motor neuron being stimulated (withdrawal) and the opposite limb being extended in order to support the body’s weight
true
Circuits that give rise to rhythmic motor activity are called:
central pattern generators
True or False: You spend an increased time in the "stance" phase if you increase locomotion
false
True or False: The mammalian cycle of locomotion is organized by central pattern generators in the spinal cord
true
True or False: Neuronal modules for flexion and extension antagonism comprise excitatory neurons and reciprocally connected inhibitory interneurons
true