NEURO 7 Flashcards
Lateral corticospinal tract
function
decussation
motor
pyramidal decussation at cervicomedullary junction
Posterior column-medial lemniscal pathway
function
location
sensory (vibration, propioception, fine touch)
internal arcuate fibers at lower medulla
Anterolateral pathway
function
location
sensory (pain, temperature, crude touch)
anterior commissure in spinal cord
sensory neruon bodies located in
dorsal root ganglia
Sensory neuron fiber A-alpha Name Myelination Receptors Sensory modalities
I
Yes
Muscle spindle, golgi tendon
propioception
Sensory neuron fiber A-beta Name Myelination Receptors Sensory modalities
II
Yes
Muscle spindle, Meissner’s corpuscle, Merkel’s receptor, Pacinian corpuscle, Ruffini ending, hair receptor
Superficial touch, proprioception, deep touch, vibration
Sensory neuron fiber A-delta Name Myelination Receptors Sensory modalities
III
Yes
Bare nerve ending
Pain, cool temperature, itch
Sensory neuron fiber C Name Myelination Receptors Sensory modalities
IV
No
Bare nerve ending
pain, warm temperature, itch
Order of sensory neuron fibers from small to large
C < A-delta < A-beta < A-alpha
Lesions of somatosensory cortex and adjacent regions cause
cortical sensory loss
Gate control theory
sensory inputs from large A-beta fibers reduce pain transmission through dorsal horn
Reduce chronic pain by activating
A-beta fibers - shaking thumb after hammer
periaqueductal gray receives inputs from ___,___,___ and inhibits pain transmission in the ___
hypothalamus, amygdala, cortex
rostral ventral medulla
What modulates pain in the dorsal horn
serotonergic 5-Ht
contributes to pain modulation through H3 receptors
histamine
opiate receptors and endogenous opiate peptides found in high concentration
key points in pain modulatory pathways
thalamus is part of what part of the brain
diencephalon
Ventral posterior lateral nucleus
Main input
Main output
Function
Medial leniscus, spinothalamic tract
somatosensory cortex
relays input to cortex
Ventral posteromedial nucleus
Main input
Main output
Function
trigeminal lemniscus, trigeminothalamic tract, taste inputs
somatosensory and taste cortex
relays inputs to cortex
Lateral geniculate nucleus
Main input
Main output
Function
Retina
Primary visual cortex
relays inputs to cortex
Ventral lateral nucleus
Main input
Main output
Function
internal globus pallidus, deep cerebellar nuclei, substantia nigra pars reticulata
motor, premotor and supplementary motor
Relays basal gangliaand cerebellar inputs to cortex
Medial geniculate nucleus
Main input
Main output
Function
inferior colliculus
Primary auditory cortex
relays auditory inputs to cortex
Ventral anterior nucleus
Main input
Main output
Function
substantia nigra pars reticulata, internal globus pallidus, deep cerebellar nuclei
Frontal lobe
Relays basal ganglia and cerebellar inputs
Pulvinar
Main input
Main output
Function
Tectum
Paritotemporooccipital association
Behavioral orientation towards relevant visual stimuli
Mediodorsal nucleus
Main input
Main output
Function
amygdala, olfactory, limbic basal ganglia
frontal cortex
limbic pathways, major relay to frontal cortex
Anterior nucleus
Main input
Main output
Function
mammillary body, hippocampal foramtion
cingulate gyrus
limbic pathway
centromedian nucleus
Main input
Main output
Function
AGlobus pallidus, ARAS
striatum, cerebral cortex
motor relay for basal ganglia
Only nucleus of thalamus that does not project to cortex
reticular, consists purely of inhibitory GABAergic neurons
Lesions in posterior column - medial leniscal pathway
tingling, numbness, bandlike sensation, fingers wrapped in gauze
Lesions in anterolateral pathways
sharp, burning, searing pain
Lesions of parietal lobe or primary sensory cortex
CL numb tingling and pain
Lesions of thalamus
CL pain = Dejerine - ROussy syndrome
Lesions of cervical spine
Lhermitte’s sign = electricity like sensation down back w/ neck flexion
Lesions of nerve roots
radicular pain which radiates in dermatomal pattern
dysesthesia
unpleasant abnromal sensation
allodynia
painful sensation provoked by nonpainful stimuli
hyperpathia or hyperalgesia
enhanced pain to painful stimuli
hypesthesia
decreased sensation
spinal shock
flaccid paralysis below lesion
What is used to treat acute traumatic spinal cord lesions
steroids
What usually causes chronic myelopathy
degenerative disorders of the spinal
cord compression by tumors can eventually cause
irreversible loss of ambulation
what causes infarction of spinal cord
anterior spinal artery occlusion due to trauma, aortic dissection, thromboemboli and disc emboli
MRI of myelitis
T2 bright areas, CSF has elevated WBCs, lymphocytic predominant
Primary Somatosensory cortex lesion
deficit is CL, discriminative touch and joint position most severely affected or cortical sensory loss is present w/ extinction sterognosis and graphesthesia
Thalamic Ventral posterior lateral and medial nuclei lesion
deficit is CL, more noticeable in hand, face, foot - all sensory modalities involved
Lateral pons or medulla lesion
IL: causes loss of pain and temp in face
CL: causes loss of pain and temp in body
Medial medulla lesion
CL loss of vibration and joint position sense
Nerve root lesion
glove and stocking distribution
Transverse cord lesion
Sensory and motor pathway interrupted
Hemicord Lesion = Brown-Sequard Syndrom
Lateral corticospinal tract damage = IL UMN weakness
Posterior column damage = IL loss of vibration and joint position sense
Anteriolateral system damage = CL loss of pain and temperature ** may also cause sensory loss to pain and temperature on IL
Small Central cord syndrome
bilateral regions of suspended sensory loss to pain and temperautre
Lesion of cerival cord
cape distribution of pain and temperature
Large Central cord syndrome
sacral sparing
Posterior cord syndrome
loss of virbation and position sense below the level of the lesion
Anterior cord syndrome
Anterolateral pathway: loss of pain and temperature below lesion
Anterior horn: LMN weakness at level of lesion
Large = incontinence and UMN
Bladder
Normal function
Lesion in bilateral medial frontal micturition centers
Lesion below pontine micturiton center
Lesion of peripheral nerve S2-S4
completely volunteer
medial frontal micturition center = activates voiding/detrusor reflex which is regulated by pontine micturition center
urine flow and bladder emptying no longer under voluntary control
flaccid, acontractile (atonic) bladder
flaccid areflexic bladder
Bowel
Normal
Sphincter closure maintained by internal smooth muscle sphincter innervated by parasympathetics, external striated muscle sphincter innervated from Onuf’s nucleus and pelvic floor muscles from sacral anterior horn
Bowel lesions
fecal incontinence and constipation
Sexual function
Normal
sensation from genitalia via pudendal nerve S2-S4, lubrication from Bartholin’s glands (parasympathetic) and increased vaginal blood flow (sympathetic), ejaculation sympathetic
Sexual function lesion
reflex erection and ejaculation possible but variable
