Internal configuration – cerebral cortex

Six cortical layers

The cerebral cortex consists of several cell and fibre types, the arrangement and abundance of which vary by location. Those regional differences characterize the cellular architecture of the cerebral cortex. Most of it consists of six main layers, namely (from superficial to deep):

1. Molecular (plexiform) layer
   characterized by a network of parallel fibres that are perpendicular to the surface
2. External granular layer
   characterized by small cells that have short axons
3. External pyramidal layer (pyramidal cell layer)
   characterized by medium-size pyramidal cells
4. Internal granular layer

   characterized by many small cells with short axons

5. Internal pyramidal (ganglionic) layer

   characterized by larger pyramidal cells

6. Multiform (fusiform) layer

   characterized by fusiform cells

Brodmann areas

Several classifications map various areas of the cortex. The most widely used is Brodmann’s, the main areas being:

• Primatory somatosensory cortex (1, 2, 3)
  • Lateral view of the right cerebral hemisphere
  • Medial view of the left cerebral hemisphere
• Primary motor cortex (4)
  • Lateral view of the right cerebral hemisphere
  • Medial view of the left cerebral hemisphere
• Primary visual cortex (17)
  • Lateral view of the right cerebral hemisphere
  • Medial view of the left cerebral hemisphere
• Auditory cortex (41-42)
   
• Broca's area (44-45)