Cranial Nerves

• Lobes of the cerebrum

  • Frontal
  • Parietal
  • Temporal
  • Occipital
  • Insular
• Frontal lobe


  • Motor control, concentration, verbal communication, decision making, planning, personality
• Parietal lobe


  • Serves general sensory functions, like evaluating shape and texture of objects
• Temporal lobe


  • Functions include hearing and smell
• Occipital lobe


  • Functions in vision and visual memories

  
• Insula


  • Functions in memory and sense of taste
• Primary motor cortex


  • Located in precentral gyrus, controls skeletal muscle activity on opposite side of body
• Motor speech area (Broca's area)


  • Located in inferolateral portion of left frontal lobe, controls movements for vocalization
• Primary somatosensory cortex


  • Located in postcentral gyrus, receives somatic sensory information

  
• Somatosensory association area


  • Integrates touch information allowing us to identify objects by feel
• Primary visual cortex


  • Located within occipital lobe

  
• Visual association area


  • Surrounds primary visual cortex, integrates color, form, memory to allow object identification
• Primary auditory cortex


  • Located within temporal lobe
• Auditory association area


  • Located in temporal lobe, interprets sounds and stores/retrieves sound memories
• Primary olfactory cortex


  • Located within temporal lobe, provides conscious awareness of smells
• Primary gustatory cortex


  • Located within insula, involved in processing taste information
• Prefrontal cortex


  • Complex thought, judgment, personality, planning, deciding

  
• Wernicke's area


  • Typically located in left hemisphere, involved in language comprehension
• Autism affects 1 in 88 U.S. children, with higher incidence in males
• Association tracts


  Connect regions of cerebral cortex within same hemisphere
• Commissural tracts


  Connect regions in different hemispheres, include corpus callosum
• Projection tracts


  Link cerebral cortex to inferior brain regions and spinal cord, pass through internal capsule

  
• Petalias are anatomical asymmetries in the brain
• Central white matter


  Lies deep to gray cerebral cortex, composed of myelinated axons grouped into tracts

  
• Types of white matter tracts

  • Association tracts
  • Commissural tracts
  • Projection tracts
• Association tracts


  • Connect regions of cerebral cortex within same hemisphere
  • Arcuate fibers: short tracts connecting neighboring gyri
  • Longitudinal fasciculi: longer tracts connecting gyri in different lobes
• Commissural tracts


  • Connect regions in different hemispheres
  • Include corpus callosum, anterior and posterior commissure
• Projection tracts


  • Link cerebral cortex to inferior brain regions and spinal cord
  • Corticospinal tracts carry signal from cerebral cortex to spinal cord
  • As this projection tract passes between thalamus and cerebral nuclei it is called the internal capsule

  
• Petalias


  Anatomical asymmetries, protrusion of a lobe on one side compared to other side
• Right-handed individuals tend to have right frontal petalias and left occipital petalias, left-handed individuals tend to show the opposite
• Cerebral lateralization


  Two sides of cerebrum exhibit differences in higher-order functions

  
• Categorical hemisphere (usually left)

  • Specialized for language abilities, functions in categorization and analysis, contains Wernicke area and motor speech area
• Representational hemisphere (usually right)

  • Concerned with visuospatial relationships, imagination, comparison of senses
• The two hemispheres communicate through the corpus callosum and other commissures
• Lateralization


  Develops in early childhood, seen prior to 5-6 years of age
• Lateralization differences between sexes

  • Women's posterior corpus callosum is thicker (more connections)
  • Males suffer more functional loss when one hemisphere damaged
• Lateralization and handedness


  • In right handers, the left hemisphere is almost always categorical, speech-dominant
  • Left-handed individuals may have either hemisphere be categorical
• Epilepsy


  Neurological disorder, neurons transmitting action potentials too frequently and rapidly
• Epilepsy treatment


  • Usually controlled by medications, but may require surgical removal of part of brain
  • In most severe cases, may require hemispherectomy: removal of side of brain responsible for seizure activity
• Cerebrovascular accident (CVA, or stroke)


  Reduced blood supply to part of brain, due to blocked arterial blood vessel or hemorrhage