Somatosensory Pathways 2 Flashcards
Function of ALS
nondiscriminative touch, thermal and nociceptive sensations
Function of direct spinothalamic pathways
nondiscriminative tactile, innocuous thermal, and nociceptive signals
Function of spinothalmic fibers
ALS fibers ascent directly to VPL and VPI
function of spinobulbar fibers
info from SC ascend to different brainstem nuclei
spinohypothalamic fibers function
somatosensory info from posterior horns that go to hypothalamus
Spinomesencephalic fiber function
terminate in midbrain reticular formation
What arteries supply ALS
arterial vasocorona and sulcal branches of anterior spinal artery
What happens when main arteries to ALS are occluded (arterial vasocorona and sulcal branches of ASA)
patchy loss of nociceptive, thermal, and touch over contralateral side of body
What occurs in hemisection of SC
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
What is a characteristic pattern for when the pars caudalis/spinal trigeminal tract is damaged
onion peel sensory loss
Where do second order axons from caudal nucleus decussate and ascend
anterior trigeminothalamic tract
Where do tertiary axons extend to
posterior limb of internal capsule
What is the blood supply to the trigeminal structures in medulla
PICA and Posterior spinal a.
What plays an important role in arousal and alertness
Trigeminal input into reticular formation, facilitates ascending reticular activating system
What is responsible for regulating wakefulness and sleep/wake transitions
Reticular fibers
Where does pars oralis extend to
from level of pons to superior medulla
Where does pars interpolaris extend to
from superior medulla to obex
Unilateral lesion of CN V symptoms
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
Alternating analgesia lesion of CN V symptoms
ipsilateral hemianalgesisa of face and contralateral hemianalagesia of body
What leads to alternating analgesia
Brainstem lesions in upper medulla, may destroy primary fibers in teh spinal trigeminal tract and secondary fibers in spinal lemniscus
Alternating trigeminal hemiplegia symptoms
ipsilateral trigeminal anesthesia and paralysis, contralateral spastic hemiplegia
What causes alternating trigeminal hemiplegia
unilateral destruction of the trigeminal nerve and CST in the pons
What causes lateral medullary syndrome
PICA lesion.
Symptoms of lateral medullary syndrome (Wallenberg syndrome)
contralateral loss of pain and temp. with ipsilateral loss of modalities over face
What causes corneal reflex
fibers on V1 terminate in spinal trigeminal nucleus, second collaterals bilaterally into facial motor nucleus, eyes blink if exposed to stimulus
