Descending motor tracts

Question 1

What is the origin of the cortico-spinal tract?

Answer 1

Primary motor cortex

Question 2

What is the origin of the rubro-spinal tract?

Answer 2

Red nucleus in the midbrain

Question 3

What is the origin of reticulo-spinal tract?

Answer 3

Medial - reticular formation in pons
Lateral - reticular formation in medulla

Question 4

What is the origin of the vestibulo-spinal tract?

Answer 4

Vestibular nuclei in the upper medulla

Question 5

Where does the cortico-spinal tract receive its input from?

Answer 5

The motor planning area and other motor areas in the frontal lobe

Question 6

Where does the rubrospinal tract receive input from?

Answer 6

Cerebellum and cerebral cortex

Question 7

Where does the reticulo-spinal tract receive its input from?

Answer 7

Cerebellum and basal ganglia

Question 8

Where does the vestibulo-spinal tract receive its input from?

Answer 8

inner ear vestibular hair cells in the labyrinthine apparatus via the vestibulocochlear (VIII) Nerve

Question 9

What is the function of the corticospinal tract?

Answer 9

Lateral - motor commands to skeletal muscles in distal parts of limbs (90%)
Medial - motor commands to trunk and proximal limbs (10%)

Question 10

What is the function of the rubrospinal tract?

Answer 10

Precise movements of distal limbs, gross limb movements of large muscles, upper limb

Question 11

What is the function of the reticulospinal tract?

Answer 11

Medial - facilitates extensor reflexes, inhibits flexor reflexes, increases muscle tone in axial skeleton and proximal limbs

Lateral - facilitates flexor reflexes, inhibits extensor reflexes, decreases muscle tone in axial skeleton and proximal limbs

Question 12

What is the function of the vestibulospinal tract?

Answer 12

Medial - reflex movements of head and neck
Lateral - effect motor neurones innervating limb muscles, postural equilibrium

Question 13

Describe the upper motor neuron for the corticospinal tract

Answer 13

Cell body in the primary motor cortex, corona radiata project to the internal capsule, lateral tract crosses in medulla, anterior crossed at spinal level, both synapse onto anterior horn cell

Question 14

Describe the upper motor neuron for the rubrospinal tract

Answer 14

Cell body in red nucleus, descends the lateral column, terminates in anterior horn of cervical region

Question 15

Describe the upper motor neuron for the reticulospinal tract

Answer 15

Cell body in reticular nuclei, terminates prior to anterior horn cell

Question 16

Describe the upper motor neuron for the vestibulospinal tract

Answer 16

Cell body in vestibular nuclei, terminates prior to anterior horn cell

Question 17

When does the corticospinal tract cross over?

Answer 17

Lateral - decussation or pyramids in the medulla

Anterior - anterior commissure in spinal cord

Question 18

When does the rubrospinal tract cross over?

Answer 18

Ventral segmental decussation in midbrain

Question 19

When does the reticulospinal tract cross over?

Answer 19

Medial - doesn’t cross
Lateral - some fibres cross in medulla

Question 20

What is the lower motor neuron for the corticospinal tract?

Answer 20

Alpha neuron - anterior horn cell to neuromuscular junction

Question 21

What is the lower motor neuron for the rubrospinal tract?

Answer 21

Alpha and some gamma - anterior horn cell to NMJ and muscle spindles

Question 22

What is the lower motor neuron for the reticulospinal tract?

Answer 22

Alpha and gamma - anterior horn cell to NMJ and muscle spindles

Question 23

What is the lower motor neuron for the vestibulospinal tract?

Answer 23

alpha and game - anterior horn cell to NMJ and muscle spindles