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.

Table of contents

1 Laminar pattern
2 Classification
3 Related topics

Laminar pattern

The standard areas of cortex (isocortex) is characterized as having six distinct layers. From outside inward:

Molecular layer
External granular layer
External pyramidal layer
Internal granular layer
Internal pyramidal layer
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.
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.
Proisocortex, Brodmann areas 24, 25, 32.
Periallocortex is cortical areas adjacent to allocortex.

Based on supposed developmental differencies the following classification also appears:

Neocortex that corresponds to isocortex.
Archicortex
Paleocortex

In addition, cortex may be classified on the basis of gross topographical conventions into the following:

Temporal Cortex
Parietal Cortex
Frontal Cortex
Occipital Cortex
Limbic Cortex
Insular Cortex