Neuro 7 Somatosensory

Front 1

where would a lesion cause decreased pinprick, temperature, vibration, and light tough sensation in the right face and body?

Back 1

left ventral posterior thalamus (VPL and VPM); possibly caused by infarct of middle cerebral, internal carotid, or posterior cerebral aa. (lacunar infarction)

Front 2

where would a lesion cause paraplegia and a bilateral T10 sensory level to pinprick, touch, vibration, and proprioception?

Back 2

spinal cord at T10 level (T9 vertebral bone)

Front 3

what's the difference b/w fasciculus gracilis/cuneatus and nucleus gracilis/cuneatus?

Back 3

in the posterior column-medial lemniscal pathway, 1st order neurons ascend in the fasciculus gracilis (lower body) or cuneatus (upper body) and synapse onto 2nd order neurons in the nucleus gracilis/cuneatus in the caudal medulla

Front 4

touch sensation for the face relay via which thalamic nuclei to the somatosensory cortex?

Back 4

VPM

Front 5

what kind of axons are found in the posterior column-medial lemniscal pathway?

Back 5

large-diameter, myelinated axons (proprioception, vibration, fine touch)

Front 6

what kind of axons are found in the anterolateral pathway?

Back 6

smaller-diameter and unmyelinated axons (pain, temp., crude touch)

Front 7

where do the axons first synapse in the anterolateral pathway?

Back 7

immediately in the gray matter, mainly in the dorsal horn marginal zone (lamina I), and in lamina V

Front 8

what would result from a lesion to the anterolateral pathway at T5?

Back 8

loss of contralateral pain and temp. at T8 and below (it takes 2-3 spinal segments for the fibers to decussate)

Front 9

which pathway carries pain and temp. sensation for the face?

Back 9

trigeminothalamic tract

Front 10

what is the function of the spinoreticular tract?

Back 10

emotional and arousal aspects of pain

Front 11

describe the pathway of the spinoreticular tract

Back 11

terminates on the medullary-pontine reticular formation and then projects to the intralaminar thalamic nuclei

Front 12

what is the function of the spinomesencephalic tract?

Back 12

central modulation of pain

Front 13

where does the spinomesencephalic tract synapse?

Back 13

midbrain periaqueductal gray matter and the superior colliculi

Front 14

Pt. has a lesion of the left half of the spinal cord. Which side of the pt.'s body will have decreased vibration and joint position sense below the lesion?

Back 14

lesion is below caudal medulla, so ipsilateral loss of vibration and joint position (left)

Front 15

Pt. has a lesion of the left half of the spinal cord. Which side of the pt.'s body will have decreased pain and temp. sense below the lesion?

Back 15

contralateral loss of pain and temp. (right)

Front 16

Pt. has a lesion of the left half of the spinal cord. Which side of the pt.'s body will have weakness below the lesion?

Back 16

lesion is below pyramidal decussation, so ipsilateral weakness (left)

Front 17

Pt. has a lesion of the left cerebral cortex. Which side of the pt.'s body will have decreased vibration and joint position sense below the lesion?

Back 17

right (contralateral)

Front 18

Pt. has a lesion of the left cerebral cortex. Which side of the pt.'s body will have decreased pain and temp. sense below the lesion?

Back 18

right (contralateral)

Front 19

Pt. has a lesion of the left cerebral cortex. Which side of the pt.'s body will have weakness below the lesion?

Back 19

right (contralateral)

Front 20

where is the secondary somatosensory association cortex?

Back 20

within the Sylvian fissure, along its superior margin in the parietal operculum

Front 21

what is gate control theory?

Back 21

sensory inputs from large-diameter, non-pain A-β fibers reduce pain transmission through the DORSAL HORN

Front 22

describe the central pathway involved in pain modulation

Back 22

neuron from the dorsal horn gray matter, dorsolateral funiculus synapses on the rostral ventral medulla (RVM) at the pontomedullary junction and then projects to the periaqueductal gray matter

Front 23

what is the relationship of the hypothalamus to the thalamus?

Back 23

hypothalamus is immediately ventral (inferior)

Front 24

somatosensory pathways from the spinal cord relay in which thalamic nucleus

Back 24

VPL

Front 25

somatosensory pathways from the cranial nerves relay in which thalamic nucleus

Back 25

VPM

Front 26

visual information is relayed in which thalamic nucleus?

Back 26

LGN (lateral geniculate nucleus) "lateral light"

Front 27

auditory information is relayed in which thalamic nucleus?

Back 27

MGN (medial geniculate nucleus) "medial music"

Front 28

motor pathways leaving the cerebellum and basal ganglia relay in which thalamic nucleus

Back 28

VL

Front 29

inferior colliculus projects to which thalamic nucleus

Back 29

MGN

Front 30

what is the function of the pulvinar nucleus?

Back 30

behavioral orientation toward relevant visual and other stimuli

Front 31

what is the function of the mediodorsal nucleus (MD) nucleus?

Back 31

cognition; limbic pathways, major relay to frontal cortex

Front 32

what is the function of the rostral intralaminar nucleus?

Back 32

maintain alert consciousness

Front 33

which nuclei relay basal ganglia and cerebellar inputs to the cortex?

Back 33

VL and VA

Front 34

which nuclei relay limbic input to the cortex?

Back 34

MD and anterior nuclei

Front 35

which nucleus does NOT project to the cortex?

Back 35

reticular; it receives inputs from other thalamic nuclei and the cortex and then projects back to the thalamus

Front 36

what kind of neurons are found in the reticular nucleus?

Back 36

inhibitor GABAergic

Front 37

lesions to which pathway cause tingling or numb sensation?

Back 37

posterior column-medial lemniscal

Front 38

what is Dejerine-Roussy syndrome?

Back 38

severe contralateral pain caused by a lesion of the thalamus

Front 39

what is Lhermitte's sign?

Back 39

electricity-like sensation running down the back and into the extremities upon neck flexion; caused by a lesion of the cervical spine

Front 40

dysesthesia

Back 40

unpleasant, abnormal sensation

Front 41

allodynia

Back 41

painful sensations provoked by minor stimuli (aka hyperpathia)

Front 42

what is spinal shock?

Back 42

flaccid paralysis below the lesion, loss of tendon reflexes, decreased sympathetics causing moderately decreased BP, and absent sphincteric reflexes and tone

Front 43

what is most severely affected with a lesion to the primary somatosensory cortex?

Back 43

discriminative touch and proprioception, but all modalities may be involved

Front 44

why would a large lesion to the thalamus also involve hemiparesis or hemianopia?

Back 44

it could involve the internal capsule (lateral to thalamus), lateral geniculate, or optic radiations

Front 45

what would a lesion to the lateral pons or lateral medulla cause?

Back 45

loss of pain and temperature to the face on the ipsilateral side and loss of pain and temperature in the body on the contralateral side; the anterolateral pathway and spinal trigeminal nucleus are lateral to the posterior column pathway

Front 46

what would a lesion to the medial medulla cause?

Back 46

contralateral loss of vibration and proprioception (facial sparing)

Front 47

what would a central cord lesion cause?

Back 47

bilateral loss of pain and temperature sense (anterolateral pathway crosses in the anterior commissure)

Front 48

where would a lesion cause the classic cape distribution?

Back 48

central cervical cord lesion (C5-C6 is the lateral arm)

Front 49

lesions to which tract cause UMN signs? LMN signs?

Back 49

UMN - lateral corticospinal tract
LMN - anterior horn cells

Front 50

what characterizes anterior cord syndrome?

Back 50

loss of pain and temp. sensation below the lesion, damage to the anterior horn cells produces LMN weakness at the level of the lesion, and incontinence

Front 51

vitamin B12 deficiency and tabes dorsalis (tertiary syphilis) affect what part of the spinal cord?

Back 51

posterior - loss of vibration and proprioception

Front 52

why might a lesion to the anterior cord cause incontinence?

Back 52

the descending pathways controlling sphincter function tend to be more ventrally located

Front 53

what controls the pelvic floor muscles?

Back 53

voluntary somatic motor fibers from anterior horn cells at S2-S4

Front 54

what controls the urethral and anal sphincters?

Back 54

voluntary somatic motor fibers from Onuf's nucleus at S2-S4

Front 55

describe the detrusor reflex

Back 55

voluntary relaxation of the external urethral sphincter, which triggers inhibition of sympathetics to the bladder neck (relaxes), and parasympathetics cause the detrusor to contract

Front 56

what would bilateral lesions to the frontal micturition center cause?

Back 56

reflex activation of pontine and spinal micturition centers when the bladder is full; urine flow and bladder emptying are normal, but are NOT under voluntary control

Front 57

in females, what is responsible for secretion of lubricating mucus

Back 57

Bartholin's glands (parasympathetics)

Front 58

graphesthesia

Back 58

unable to identify letter or number traced onto their palm

Front 59

stereognosis

Back 59

unable to identify various objects by touch

Front 60

where would a lesion cause agraphesthesia and astereognosis?

Back 60

contralateral sensory cortex

Front 61

dysmetria

Back 61

abnormal overshoot or undershoot during movements toward a target