Cortical Control of Movement

Question 1

The axons of the cortical upper motor neurons that contact lower motor neurons in the brainstem form the __________ tract.

Answer 1

Corticobulbar

Question 2

The upper motor neurons in the brainstem give rise to the ___________.

Answer 2

Medial pathway

Question 3

Medial pathway contains 3 tracts:

Answer 3

1. Tectospinal tract
2. Reticulospinal tract
3. Vestibulospinal tract

Question 4

Tectospinal tract

Answer 4

That controls the activity of neck muscles and coordinate head movements with eye movements

Question 5

Reticulospinal tract

Answer 5

Controls the activation of axial/proximal muscles and central pattern generators (this tract is vestigial in humans)

Question 6

Vestibulospinal tract

Answer 6

Controls the activation of postural muscles

Question 7

The principle of connectivity between the upper and lower motor neurons is:

Answer 7

one to many, many to one.

Question 8

Function of the premotor cortex

Answer 8

The main role of the premotor cortex is in planning externally guided movements. These movements are motivated by the presence of objects or visual cues in the environment. Ex. catching a ball, avoiding an obstacle, etc.

Question 9

Function of the supplementary motor cortex

Answer 9

Critical for internally guided movements and in coordinating movement sequences.

Question 10

The ____ motor area coordinates emotional movements, motivated by reward and punishment.

Answer 10

cingulate

Question 11

Upper Motor syndrome time course: (4)

Answer 11

1. weakness
2. exaggerated reflexes
3. clonus (muscular spasm)
4. Spasticity (after 2-4 weeks) and increases over time

Question 12

3 possible causes of spasticity:

Answer 12

1. Changes in the firing threshold, motor neuron becomes smaller and input resistance increases
2. Denervation supersensitivity
3. Denervated lower motor neurons, might receive inputs from intact terminals that give rise to branches that will eventually synapse on the denervated neuron.