Pathways & Lesions

Question 1

Function of Dorsal Columns-Medial Lemniscus

Answer 1

• proprioception
• vibration
• discriminatory touch
• stereognosis

Question 2

function of spinothalamic tracts

Answer 2

pain & temperature

Question 3

function of ventral spinothalamic tract

Answer 3

light/crude touch

Question 4

function of lateral corticospinal tract

Answer 4

motor to distal flexor muscles

Question 5

function of ventral corticospinal tract

Answer 5

motor to core muscles

Question 6

what are the primary afferent neurons of dorsal columns-medial lemniscus?

Answer 6

Fasciculus cuneatus (T6^)
Fasciculus gracilis (T6_)

Question 7

what are the secondary afferent neurons of dorsal columns-medial lemniscus?

Answer 7

medial lemniscus

Question 8

primary afferent neurons of the dorsal columns-medial lemniscus pathway synapse with _____

Answer 8

nucleus cuneatus
nucleus gracilis

Question 9

where do fibers in the dorsal columns-medial lemniscus cross?

Answer 9

great sensory decussation (GSD)

Question 10

what are the primary afferent neurons of the spinothalamic tracts?

Answer 10

dorsolateral fasciculus (DLF)

Question 11

what do the primary afferent neurons of spinothalamic tracts synapse with?

Answer 11

nucleus proprius

Question 12

what are the secondary afferent neurons of the spinothalamic tract?

Answer 12

lateral spinothalamic tract (LSTT)

Question 13

where do fibers of the spinothalamic tracts cross?

Answer 13

ventral white commissure (VWC)

Question 14

where do secondary afferent fibers of ventral spinothalamic tracts run?

Answer 14

alongside lateral spinothalamic tract

Question 15

where do fibers of lateral corticospinal tract cross?

Answer 15

pyramidal decussation (85%)

Question 16

where do fibers of ventral corticospinal tract cross?

Answer 16

• fibers do not cross at pyramidal decussation (15%) - remain ipsilateral
• cross at ventral white commissure

Question 17

what are the UMNs of corticospinal tract?

Answer 17

lateral corticospinal tract (LCST)
ventral corticospinal tract (VCST)

Question 18

what are the LMNs of corticospinal tract?

Answer 18

ventral roots (synapse in ventral horn of spinal cord)

Question 19

in all tracts, a lesion above the crossing of fibers will cause ____ loss of function

Answer 19

contralateral

Question 20

in all tracts, a lesion below the crossing of fibers will cause ____ loss of function

Answer 20

ipsilateral

Question 21

lesion of fasciculus cuneatus at T3

Answer 21

ipsilateral loss of proprioception/vibration/touch from T3-T6

Question 22

lesion of fasciculus gracilis at T8

Answer 22

ipsilateral loss of proprioception/vibration/touch from T8 down

Question 23

lesion of fasciculus gracilis at T2

Answer 23

ipsilateral loss of proprioception/vibration/touch from T6 down

Question 24

lesion of medial lemniscus

Answer 24

contralateral loss of proprioception/vibration/touch from C1 down

Question 25

lesion of nucleus cuneatus

Answer 25

ipsilateral loss of proprioception/vibration/touch from C1-T6

Question 26

lesion of nucleus gracilis

Answer 26

ipsilateral loss of proprioception/vibration/touch from T6 down

Question 27

lesion of dorsolateral fasciculus at T4

Answer 27

ipsilateral loss of pain & temperature from T4,5,6

Question 28

lesion of nucleus proprius at T8

Answer 28

ipsilateral loss of pain & temperature at T10

Question 29

lesion of ventral white commissure at T8

Answer 29

bilateral loss of pain & temperature at T10

Question 30

lesion of lateral spinothalamic tract at T8

Answer 30

contralateral loss of pain & temperature from T10 down

Question 31

lesion of spinocerebellar tracts

Answer 31

ataxia

Question 32

lesion of ventral corticospinal tracts

Answer 32

Contralateral core weakness

Question 33

lesion of lateral corticospinal tracts

Answer 33

ipsilateral spastic paralysis (distal flexors) from level of lesion down

Question 34

lesion of ventral root

Answer 34

flaccid paralysis

Question 35

lesion of corticospinal tracts

Answer 35

contralateral spastic paralysis

Question 36

lesion of spinal tract (nucleus) of trigeminal

Answer 36

ipsilateral loss of P+T from face

Question 37

lesion of chief sensory nucleus of trigeminal

Answer 37

ipsilateral loss of touch from face

Question 38

lesion of mesencephalic nucleus of trigeminal

Answer 38

ipsilateral loss of proprioception from face

Question 39

lesion of motor nucleus of trigeminal

Answer 39

paralysis of mastication muscles (jaw deviation to side of lesion)

Question 40

lesion of trigeminal lemniscus below mid pons

Answer 40

contralateral loss of P+T from face

Question 41

lesion of trigeminal lemniscus above mid pons

Answer 41

contralateral loss of P+T, touch, proprioception from face

Question 42

lesion of CN V

Answer 42

- ipsilateral anesthesia of face (loss of P+T, touch, proprioception) - inability to bite down (mastication) - sometimes causes trigeminal neuralgia (lose all but pain)

Question 43

lesion of subthalamus

Answer 43

hemiballismus: uncontrollable, violent torsonal movements