Somatic sensorial system

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Somatic sensorial system

• Anatomy, function

(c) gabriela spulber 2005
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The spinal chord
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Gray matter

• Ventral horn
• Dorsal horn

White matter

• Ventral column
• Lateral column
• Dorsal column

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(No Transcript)
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Ventral root ? efferent somatic and visceral
fibers Dorsal root ? afferent somatic and
visceral fibers
motor and sensory innervation
31 pairs of spinal nerves
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Role of spinal cord

• conductor of impulses between the brain and the
  periphery
• ascending / descending patways
• intrinsic neuronal circuits subserving spinal
  reflexes

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The sensorial system
touch (submodalities!) limb position senses pain
/ itch temperature senses

• mediate modalities

• maintenance of arousal
• sensory regulation of movements
• process stimuli from body surface and within the
  body
• (viscera, muscles, joints)

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Dorsal column medial lemniscal system

• touch
• limb position

Anterolateral system

• pain
• itch
• temperature

System chain of neurons linking sensory
receptors to the contralateral cerebral
cortex
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Dorsal column medial lemniscal system
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Rexed lamination
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• mechanoreceptors ? encapsulated terminals
• decussate in the medulla oblongata
• lesion?

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Anterolateral system
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• receptors
• thermoreceptors
• nociceptors
• itch receptors (histamine)
• decussate in the spinal cord

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Spinothalamic tract

• VPL ? postcentral gyrus
• VMP ? insular cortex
• MD ? anterior cingulate gyrus

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Somatotopy
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The sensory homunculus
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Posterior parietal cortex

• perception of body image
• lesion ? neglect of the contralateral half of
  the body