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