Chapter 4 and 5: Somatic Sensation Flashcards
Spinal Mechanosensory Systems
touch and pain position sense are mediated by the?
dorsal column medial lemniscal pathway
after a lesion of the DCML pathway discriminative capabilities are _______
and would have difficulty ______ with eyes closed because ________
give example
reduced
maintaining balance, reduced leg position sense
example:
- may not be able to distinguish rough and smooth ie. like grades of sandpaper
what remains after dorsal column lesion
crude touch
_______ a specialized kinda of f dorsal root ganglion neuron that provides major sensory input to the DCML system
mechanoreceptors
limb position sense are sensitive to ____________
muscle stretch (muscle spindles)
tendon tension (GTO)
what are examples of mechanoreceptors
- ruffini’s corpuscles - Deep, SLOW
- sensitive to skin stretch
- discrimination - Meissner Corpuscles - Superficial, RAPID
- ie. reading braille - merkels receptors - Superficial, SLOW
- ie. reading braille - Pacinian Corpuscles -Deep, RAPID
- most sensitive
- sensitive to skin stretch
- discrimination
The principal receptor for proprioception is ______________ which is located within the _______
the muscle spindle receptor
muscle belly
muscle spindle receptors provide information to the brain for
limb proprioception, spacial awareness of limbs
GTO can have a role in an individuals sense of
how much effort it takes to produce a motor act
how many sensory dermatomes are in the spinal cord?
31 sensory dermatomes
-
- for somatic maping
- important for depicting lesions in the spinal cord
the areas of the skin innervated by the axons in a single dorsal root is termed
dermatomes
the spinal cord has a ______ organization
dorsoventral sensory motor organization
the anterolateral system is for?
pain, temp and itch
decussation of the DCML is where
medulla then the fibres ascend in the ventral part of the medial lemniscus
the primary somatic sensory cortex has a _________ organizarion
columnar organization
thalamus usually projects to cortical layer
4th layer
neurons whose cell bodies are located in layers ____ and ______ project to other cortical areas
2 and 3
callosal neurons are located in what layers
2 and 3
corticocortical association neurons are in what later
2 and 3
descending projection neurons are located in what layers
5 and 6
BA (brodmann area)
3a and 2 :
3b and 1:
3a and 2 (both deep and skin) :
- deep
perception of body movement
(muscle, joint, and pressure sensations)
3b and 1:
- skin
touch
there are 3 major projection streams for processing mechanosensation for primary somatic sensory cortex
describe there uses
1.
2.
3.
- ventral : recognizing manipulated objects
- dorsal: localization of objects and spatialization
- rostral: movement control
*
what is unique to our protective senses?
that they engage areas of the cerebral cortex that a for emotional sensation
*
pain, temperature and itch are mediated by the _________
anterolateral system
the anterolateral system, is a collection of ___ pathways that travel in the ______portion if the ______column of the spinal cord
ascending
anterior
lateral
surgical destruction of the anterolateral system spares?
also,____
touch
limb position
people become less sensitive to pain
the anterolateral systems first relay is ?
in the dorsal horn
decussation of anterolateral system?
spinal cord level
the spinothalamic projection to the VPL nucleus transmits info to the
primary somatic sensory cortex
the ______i also importat for perception of pain quality
the spinoreticular tract relay is?
parabrachial nucleus –> targets amygdala
together the insular cortex and amygdala helps organize our
behavioural response that accompanies pain
- increase BP
- Rubbing injured site
the spinoreticular tract engages a subcortical _.
emotion pathway
the spinomescenphalic tract terminates in the _______
midbrain tectum
spinomescenphalic tract:
- projection to the tectum integrates somatic sensory information with
vision
hearing
head orientation
visceral pain is mediated by what?
dorsal horns whose axons who ascend in the dorsal columns
true or false visceral pain takes the same pathway (mechanosensory pathway)
false;
- visceral pain neurons send axons into medial portion of the dorsal columns (gracille)
- visceral pain synapses in seperate portion of the dorsal column nuclei and thalamus than the mechanosensory pathwat
itch sensitive receptors respond to ____ and are also called ______
- histamine
- pruriceptors
three principle classes of nociceptor
thermal –> temp activated
mechanical –> tissue damaged activated
polymodal –> noxious, thermal, mechanical stimuli
small diameter sensory firbes terminate primarily in the _________ of the dorsal horn
superficial laminae
pain, itch, and temp enter the spinal cord through and in
lissauer tract (white mater region that caps the dorsal horn)
this stains lightly because the axons are not heavly mylenated
laminae 1 and 2 receive info from
small- diameter myelinated and unmyelinated (c) fibres only
indicating a selective roll in pain, temp, and itch processing
laminae 3 (III) and 4 (IV) receive info from
large - diameter fibres
processing a broad range of somatic stimulis intsities
laminae 6-9 (VI-IX)
tend tor recieve much less afferent fibre information with one exception:
GTO –> terminate: laminae VII - IX (7-9)
primary muscle spindle receptors synapse directly on motor neurons
laminae V (5) recieves
both small and large fibre inputs
respond to range of stimuli
