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The structure and functional localization of the cerebral cortex II

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Motor & Sensory homunculus on the precentral gyrus
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Motor homunculus

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Sensory homunculus
Association cortex
  • 1stry motor & 1stry sensory areas are only account for small percentage of cortical surface area
  • There are large remaining areas in the cortex called association areas
  • There are 3 main association areas

    1. Prefrontal
    2. Anterior temporal
    3. Posterior parietal

Association area
Function
  • Prefrontal cortex
Associate experiences to
  1. Abstract ideas
  2. Produce judgments
  3. Emotional feelings
  4. Personality
  • Anterior temporal cortex
Store previous sensory experiences
  • Posterior parietal cortex
Stereognosis – The ability to recognize the 3D shape of an object by touch alone   

Cerebral dominance
  • The 2 hemispheres of the newborn have the same capabilities
  • During childhood, one hemisphere slowly comes to dominate the other (Only after the 1st decade that the dominance becomes fixed)
  • That’s why a 5 years old child with a damaged dominant hemisphere can easily learn to become left handed & speak well; whereas in the adult this is almost impossible
Nervous activities performed predominantly by dominant & non dominant hemispheres
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Main anatomical connections of the cerebral cortex
Function
Origin
Cortical area
Destination
Sensory
Somatosensory
  1. Most to contra lateral side of body
  2. Oral to same side
  3. Pharynx, larynx & perineum bilateral  

Ventral posterior lateral & VP medial nuclei of the thalamus
1stry somesthetic area (B 3, 2, & 1) – posterior central gyrus
2ndry somesthetic & 1stry motor areas
Vision
Lateral geniculate body
1stry visual area
(B 17)
2ndry visual area
(B 18 & 19)
Auditory
Medial geniculate body
1stry auditory area (B 41 & 42)
2ndry auditory area (B 22)
Taste
Nucleus solitarius
Posterior central gyrus (B 43)

Smell
Olfactory bulb
1stry olfactory area
2ndry olfactory area (B 28)
Motor
Fine movements
  1. Most to contra lateral side of body
  2. Extra ocular muscles, upper face, tongue, mandible & larynx are bilateral
Thalamus
Cerebellum
Basal ganglia
Somatosensory area
Pre motor area
1stry motor area
(B 4)
Motor nuclei of brain stem & anterior horn cells of spinal cord

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The structure and functional localization of the cerebral cortex II The structure and functional localization of the cerebral cortex II Reviewed by Radiology Madeeasy on August 10, 2010 Rating: 5
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