Corpus: Neocortex

The neocortex is the phylogenetically youngest part of the cerebral cortex (cortex cerebri). Due to its relatively homogeneous histological structure, it is also known as the isocortex.

The cerebral cortex is made up of the neocortex, the archicortex and the paleocortex. The neocortex consists of grey matter that surrounds the underlying white matter of the brain. It consists of approx. 20-23 billion neurons, which are arranged in 6 horizontal layers and organised in the form of columns.

In humans, the neocortex is folded for the purpose of enlarging the surface area and accordingly has bulges (gyri) and furrows (sulci).

Layers[Bearbeiten]

The following layers are distinguished from the surface in the direction of the medulla:

Lamina molecularis[Bearbeiten]

The lamina molecularis (lamina I) consists mainly of extensions of deeper neurones. Non-pyramidal cells are occasionally found.

Lamina granularis externa[Bearbeiten]

In the lamina granularis externa (lamina II) there are many small pyramidal cells (and non-pyramidal cells) that lie very close together and therefore give the impression of a collection of granules.

Lamina pyramidalis externa[Bearbeiten]

Many large pyramidal cells are found in the lamina pyramidalis externa (lamina III). The axons of the second and third layers form association and commissural fibres.

Lamina granularis interna[Bearbeiten]

The lamina granularis interna (lamina IV) contains many pyramidal cells and many non-pyramidal cells. The afferents from the specific nuclei of the thalamus, which form the so-called Baillarger strip, end in this layer.

Lamina pyramidalis interna[Bearbeiten]

The particularly large pyramidal cells in the lamina pyramidalis interna (lamina V) project to numerous extracortical centres with the exception of the thalamus.

Lamina multiformis[Bearbeiten]

The cells of the lamina multiformis (lamina VI) are morphologically very different. The axons of the pyramidal cells of this layer project to the specific nuclei of the thalamus.