W4 - Spinal Cord Tracts (Asc + Desc)

Question 1

What are the three ascending tracts called?

Answer 1

DCML pathway, spinothalamic and spinocerebellar tract

Question 2

The dorsal column carries the two DCML pathways, the fasciculus gracilis and cuneatus, what two types of information are carried here?

Answer 2

Conscious proprioception and discriminative touch

Question 3

What three bits of information are carries in the spinothalamic tract?

Answer 3

Innocuous temp, pain and crude touch

Question 4

What 3 bits of info do the two spinocerebellar tracts carry? (dorsal and ventral)

Answer 4

Movement coord, unconscious proprioception and other cutaneous sensory info

Question 5

Describe the 3 step/neuron pathway of the DCML pathways (part 1)

Answer 5

FC or FG mechanoreceptor sensory afferent from arm/leg respectively ascend through dorsal horn, this synapses in the medulla to the medial lemniscus neuron

Question 6

Describe the 3 step/neuron pathway of the DCML pathways (part 2)

Answer 6

The medial lemniscus neuron decussates and ascends to synapse with the VPL neuron in the nucleus of the thalamus

Question 7

Describe the 3 step/neuron pathway of the DCML pathways (part 3)

Answer 7

The VPL projects to the primary somatosensory cortex

Question 8

Are the diameters of the afferents in the DCML and spinothalamic pathways small or large?

Answer 8

DCML - large, STT - small

Question 9

Describe the 3 step/neuron pathway of the STT pathway (part 1)

Answer 9

Primary afferent goes into the lamina 1 and 5 of the grey matter in the SC, synapsing with a second order neuron

Question 10

Describe the 3 step/neuron pathway of the STT pathways (part 2)

Answer 10

The second order neuron decussates and ascends in either the dorsal or ventral STT, synapsing with a 3rd order neuron in the thalamus

Question 11

Describe the 3 step/neuron pathway of the STT pathways (part 3)

Answer 11

3rd order VPL neuron projects to somatosensory cortex

Question 12

Are ascending or descending tracts sensory/motor?

Answer 12

Ascending sensory and descending motor

Question 13

List the 4 descending tracts

Answer 13

Reticulospinal, vestibulospinal, rubrospinal and corticospinal

Question 14

Which descending tract directs coluntary movement, reflexes and muscle tone via alpha and gamma motor neurons?

Answer 14

Reticulospinal

Question 15

What are the only nervous fibres associated with the ANS?

Answer 15

B

Question 16

Which descending tract controls posture and reflexes of head, eye, neck when the body moves?

Answer 16

Vestibulospinal

Question 17

The rubrospinal tract originates in the midbrain red nucleus, what does it control?

Answer 17

Limb flexor muscles of upper limbs in humans

Question 18

The corticospinal tract originates in the motor cortex, what does it control?

Answer 18

Discrete, skilled movements of distal limbs

Question 19

What is the corticospinal tract the principle pathway of in humans?

Answer 19

Motor control

Question 20

Step 1 of corticospinal tract

Answer 20

Cortical axons travel via posterior limb of the internal capsule through the ventral brainstem

Question 21

Step 2 of corticospinal tract

Answer 21

Most fibres decussate at the junction between medulla and SC

Question 22

Step 3 of corticospinal tract

Answer 22

Cortical axons continue to descend through the lateral column and synapses in ventral horn to motor/interneurons