tracts/pathways for exam 2

Question 1

ascending (sensory) tracts

Answer 1

1. dorsal columns
2. spinothalamic tract
3. spinocerebellar tract

Question 2

descending (motor) tracts

Answer 2

1. corticospinal (pyramidal) tracts
2. vestibulospinal tract
3. reticulospinal tract

Question 3

fasciculus cuneatus and faciculus gracilis are

Answer 3

• unconscious proprioception
• divisions of dorsal fasciculus (white matter)

Question 4

fasciculus cuneatus controls

Answer 4

sensation of upper extremities

Question 5

fasciculus gracilis controls

Answer 5

sensation of lower extremities

Question 6

dorsal column pathway steps:

Answer 6

1. sensory signal occurs triggering action potential
2. action potential travels to DRG
3. action potential synapses @ dorsal foniculus
4. signal ascends to dorsal column nuclei in medulla
5. signal decussates midline of the brain
6. signal ascends through medial lemniscus (medulla, pons, midbrain)
7. synapses at ventral posterior lateral nucleus
8. travels to post central gyrus in cerebral cortex

Question 7

spinothalamic tract

Answer 7

1. sensation afferents to DRG
2. synapse in dorsal horn @ substantia gelatinosa with 2nd motor neuron
3. cross over to ventral & opposite side
4. synapse in lateral foniculus
5. ascends to VPL in thalamus
6. travels and synapses in post central gyrus

Question 8

corticospinal (pyramidal) pathway

Answer 8

1. signal starts at pre-central gyrus
2. descends brain stem in ventral surface of pyramids
3. decussates at the pyramids of medulla
4. descends spinal cord via white matter
5. synapse at lateral foniculus
6. some terminate here
   - others terminated on motor neurons of ventral horn to send motor signals

Question 9

dorsal columns are responsible for

Answer 9

• fine touch
• discriminatory somatosensory

Question 10

spinothalamic tract is responsible for

Answer 10

• pain and temperature sensation

Question 11

corticospinal (pyramidal) tract is responsible for

Answer 11

voluntary movement