Ascending Spinal Pathways Flashcards
anatomical types of receptors
free nerve endings - painencapsulated - touch, mechanicalspecial neural receptor cells - special/chemical senses
functional types of receptors
mechanoreceptorsnociceptorsphotoreceptorschemoreceptorsthermoreceptors
adequate stimulus
most appropriate stimulus that will allow receptor to pass current
modality
the sense it carriesex/ stimulus = lightmodality = vision
receptor potential
proportional to strength of stimulus-graded potentialat threshold - primary afferent produces action potential
pre-cenral gyrus
primary motor cortex
post-central gyrus
primary somatosensory cortex
brodmans areas post central gyrus?
3, 1, 2 somatosensory
brodmans area for pre-central gyrus?
4motor
targets for somatosensation
reflex arcreticular formationhypothlamus > limbic systemthalamus > cerebral cortexcerebellum**divergence of neurosystem
labeled line code
if you stimulate this tract-modality of this tract results in certain sensation being feltcodes modality
population code
as intensity increases number of receptors activated increased
frequency code
as intensity increases - rate of APs increases
receptor field
part of environment to which neuron responds
resolution
ability to distinguish between 2 separate stimuluslow density - large receptive field - less resolution-few number of neurons in cortexhigh density - small receptive field - more resolution-larger number of neurons in cortex
large receptive field
lower density lower resolutionfewer number of neurons in cortex
general proprioception
static position sense - know where is in spacekinesthesia - feeling movement
axons of PCML
A-alphalarge diameter, myelinated - fast
joint receptors
joint angle and tension in joint capsule
golgi tendon organs
sense tension in organs
muscle spindles
in extrafusal fibes-detect change in muscle length
skin mechanoreceptors
also signal in proprioception
proprioceptors
joint receptorsgolgi tendonsmuscle spindlesskin mechanoreceptors
discriminative touch
high degree accuracy in locationex/ graphesthesia / stereognosis
vibration
often tested with tuning fork
sensory ataxia
without coordination-lack of proprioceptiondysmetria - incorrect meteringwide base stancetruncal swaydifficult turninginaccuracy in voluntary movements
anterolateral system
nociception, temp, crude touch4 tracts
region of tracts of ALS
in anterior and lateral funiculi-anterolateral region of cord
spinothalamic tract
conscious of ALSprojects to primary somatosensory cortexprimarily from somatic structures
tracts of anterolateral system
spinothalamicspinoreticular spinomesencephalicspinohypothalamic
spinoreticular tract
projects to reticular formation-alerts our attention to painful stimulus-focus attention-some autonomic tract
reticular formation
loose group of nuclei in core of brainstem, from medulla to dicencephalon
spinomesencephalic tract
to periaqueductal greypain modulation-descend spinal cord
spinotectal tract
subset of spinomesencephalic tract”visual grasp reflex”
spinohypothalamic tract
coordinate autonomic response to stimuli-feel nausea with intense pain
emotional response to pain
RF and hypothalamus > limbic systemspinoreticular and spinohypothalamic tract
axons of anterolateral system
A-betaA-delta and Clightly or unmyelinatedsmall-medium diameter-slower conducation
A-beta axons
touch and temperatureanterolateral system
A-delta and C fibers
painanterolateral system
C-fibers
unmyelinated
