Download Rexed`s Lamina

Processing of the sensory
information
 Levels of neural integration in sensory
systems:
1. Receptor level — the sensor receptors
2. Circuit level — ascending pathways in the
CNS
3. Perceptual level — neuronal circuits in the
cerebral cortex
Processing at the Perceptual Level
Motor
cortex
Somatosensory
cortex
Thalamus
Reticular
formation
Pons
2
Circuit level
(processing in Spinal
ascending pathways) cord
Cerebellum
Medulla
Free nerve
endings (pain,
cold, warmth)
Muscle
spindle
Receptor level
(sensory reception
Joint
and transmission kinesthetic
to CNS)
receptor
1
Figure 13.2
Rexed’s Lamina
•Some important nuclei
•Substantia
gelatinosa (II)
•Nucleus proprius (IV)
•Dorsal nucleus of
Clark
•Intermediolateral cell
column
•Motor neuron pools
SUMMARY: PATHWAYS IN THE SPINAL CORD
Ascending (afferent) pathways (sensation)
Descending (efferent) pathways (motor commands)
*
*
Spinal Tracts
Dorsal Column Ascending
Pathway
 Deep touch,
visceral pain, vibration, and
proprioception
 Fasciculus gracilis and
cuneatus carry signals from
arm and leg
 Decussation of 2nd
order neuron in medulla
 3rd order neuron in
thalamus carries signal to
cerebral cortex
Spinothalamic Pathway
 Pain, pressure,
temperature, touch,
 Decussation of the
second order neuron
occurs in spinal cord
 Third order neurons
arise in thalamus and
continue to cerebral
cortex
Spinoreticular Tract
 Pain signals from tissue injury
 Decussate in spinal cord and ascend with
spinothalamic fibers
 End in reticular formation (medulla and
pons)
 3rd and 4th order neurons continue to
thalamus and cerebral cortex
Corticospinal Tract
 Precise, coordinated
limb movements
 Two neuron pathway
 upper motor neuron in
cerebral cortex
 lower motor neuron in
spinal cord
 Decussation in medulla
Nucleus reticularis
paragigantocellularis
Pain inhibitory
complex
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