Cerebral cortex
The
cerebral cortex is the extensive outer layer of
gray matter of the cerebral hemispheres, and is involved in higher
brain functions, including
sensation, voluntary
muscle movement,
thought,
reasoning, and
memory. The grooves between the Gyri (known as sulci) on the brain's surface results in much of the cortex being buried; over 60% of the cerebral cortex in primates is buried and not visible from the surface.
Cerebral cortex is typically 2-4mm thick.
Laminar pattern
The standard areas of cortex (isocortex) is characterized as having six distinct layers. From outside inward:
- Molecular layer \n# External granular layer\n# External pyramidal layer\n# Internal granular layer\n# Internal pyramidal layer\n# Fusiform layer
Classification
Based on the differencies in lamination the cerebral cortex can be classified into two major groups:
- Isocortex (homotypical cortex), the part of the cortex with six layers. \n* Allocortex (heterotypical cortex) with variable number of layers, e.g., olfactory cortex and hippocampus.
Auxiliary classes are:
- Mesocortex, classification between isocortex and allocortex where layers 2, 3 and 4 are merged. \n* Proisocortex, Brodmann areas 24, 25, 32. \n* Periallocortex is cortical areas adjacent to allocortex.
Based on supposed developmental differencies the following classification also appears:
- Neocortex that corresponds to isocortex.\n* Archicortex\n* Paleocortex
In addition, cortex may be classified on the basis of gross topographical conventions into the following:
- Temporal Cortex\n* Parietal Cortex\n* Frontal Cortex\n* Occipital Cortex\n* Limbic Cortex\n* Insular Cortex
Related topics
