Lecture 4 Flashcards
Somatosensory Functions
posture
coordination
object manipulation
object ID
avoidance of tissue damage
emotional wellness
communication
Dermatomes
sensory region of skin innervated by nerve root
Thalamic nuclei
some have a MAP
other have diffuse projections SPREAD OUT
cortex to thalamus outnumber thalamus to cortex
Categories of thalamic nuclei
relay
intralaminar
reticular
Relay nuclei
make up majority
receive inputs and project to cortex
receive connections back from cortex
Intralaminar nuclei
lie in internal medullary lamina
receive inputs and have connections back to cortex
nonspecific
main inputs/outs are from basal ganglia
Reticular nuclei
does NOT project to cortex
receive from other thalamic nuclei, projects back to thalamus
regulate thalamic nuclei
modulate alterness and attention
VPL
ventral posterior lateral
somatosensory from spinal cord
VPM
ventral posterior medial
somatosensory relays from cranial nerves
LGN
lateral geniculate nucleus
relays visual info
MGN
medial geniculate nucleus
relays auditory info
VL
ventral lateral nucleus
relays for motor pathways leaving cerebellum and basal ganglia on route to M1, PM, SMA
Anterior nuclear group
relays info from limbic pathways to anterior cingulate cortex
Pulvinar
nonspecific
relays visual and other sensory inputs to behavior centers
Mediodorsal
nonspecific
major thalamic relay info to frontal association cortex
DCML
converys proprioception, vibrations, fine touch goes to the VPL
APS
conveys pain, temperature, crude touch
goes to VPL
A-Alpha
proprioception
muscle spindle and golgi tendon organ
A-Beta
proproception = muscle spindle
merkel = vibration
Meissner = light touch, vibration
Pacinian = vibration
Ruffini = deep touch
Hair receptor = light touch
A=delta
pain
temp
itch
C fibers
pain
temp
itch
First order neurons of DCML
a beta fibers inter dorsal root
ascend to medulla
synapse in nucleus gracilis and nucleus cuneatus
Gracilis fasciculus
carries info from legs and lower trunk
Cuneate fasciculus
carries info from upper trunk
Second Order Neuron DCML
nuc. gracilis and nuc. cuneatus
decussate in arcuate fibers and form medial leminscus
synapse in VPL of thalamus
Third order neuron DCML
project through internal capsule to reach primary somatosensory cortex
muscle spindle
proprioception
merkel
vibration
Meissner
light touch, vibration
Pacinian
= vibration
Ruffini
deep touch
Hair receptor
light touch
