Somatosensory Pathways 2

Question 1

Function of ALS

Answer 1

nondiscriminative touch, thermal and nociceptive sensations

Question 2

Function of direct spinothalamic pathways

Answer 2

nondiscriminative tactile, innocuous thermal, and nociceptive signals

Question 3

Function of spinothalmic fibers

Answer 3

ALS fibers ascent directly to VPL and VPI

Question 4

function of spinobulbar fibers

Answer 4

info from SC ascend to different brainstem nuclei

Question 5

spinohypothalamic fibers function

Answer 5

somatosensory info from posterior horns that go to hypothalamus

Question 6

Spinomesencephalic fiber function

Answer 6

terminate in midbrain reticular formation

Question 7

What arteries supply ALS

Answer 7

arterial vasocorona and sulcal branches of anterior spinal artery

Question 8

What happens when main arteries to ALS are occluded (arterial vasocorona and sulcal branches of ASA)

Answer 8

patchy loss of nociceptive, thermal, and touch over contralateral side of body

Question 9

What occurs in hemisection of SC

Answer 9

contralateral loss of nociceptive and thermal sensations over body (two segments below lesion)

ipsilateral loss of discriminative tactile, vibratory and position sense over body at and below level of lesion

Question 10

What is a characteristic pattern for when the pars caudalis/spinal trigeminal tract is damaged

Answer 10

onion peel sensory loss

Question 11

Where do second order axons from caudal nucleus decussate and ascend

Answer 11

anterior trigeminothalamic tract

Question 12

Where do tertiary axons extend to

Answer 12

posterior limb of internal capsule

Question 13

What is the blood supply to the trigeminal structures in medulla

Answer 13

PICA and Posterior spinal a.

Question 14

What plays an important role in arousal and alertness

Answer 14

Trigeminal input into reticular formation, facilitates ascending reticular activating system

Question 15

What is responsible for regulating wakefulness and sleep/wake transitions

Answer 15

Reticular fibers

Question 16

Where does pars oralis extend to

Answer 16

from level of pons to superior medulla

Question 17

Where does pars interpolaris extend to

Answer 17

from superior medulla to obex

Question 18

Unilateral lesion of CN V symptoms

Answer 18

anesthesia/loss of general sensation in trigeminal dermatomes
loss of jaw jerk reflex
atrophy of ms. of mastication
loss of ipsilateral and consensual corneal reflex

Question 19

Alternating analgesia lesion of CN V symptoms

Answer 19

ipsilateral hemianalgesisa of face and contralateral hemianalagesia of body

Question 20

What leads to alternating analgesia

Answer 20

Brainstem lesions in upper medulla, may destroy primary fibers in teh spinal trigeminal tract and secondary fibers in spinal lemniscus

Question 21

Alternating trigeminal hemiplegia symptoms

Answer 21

ipsilateral trigeminal anesthesia and paralysis, contralateral spastic hemiplegia

Question 22

What causes alternating trigeminal hemiplegia

Answer 22

unilateral destruction of the trigeminal nerve and CST in the pons

Question 23

What causes lateral medullary syndrome

Answer 23

PICA lesion.

Question 24

Symptoms of lateral medullary syndrome (Wallenberg syndrome)

Answer 24

contralateral loss of pain and temp. with ipsilateral loss of modalities over face

Question 25

What causes corneal reflex

Answer 25

fibers on V1 terminate in spinal trigeminal nucleus, second collaterals bilaterally into facial motor nucleus, eyes blink if exposed to stimulus