Cerebral cortex Flashcards
Cerebral cortex
Forms the outer layer of cerebral hemisphere
It is a layer that usually contains lots of nerve cell bodies, dendritic arborizations and synaptic connections
The cerebral cortex has a laminar alignment – AKA arranged in layers
How many layers are there?
6
How does one distinguish between the cell layers?
distinguish between the layers based on the size and the shape of the neuronal cell bodies within each cell layer
Name the six layers
From superficial to deep
Molecular (plexiform) - layer I
External granular - layer II
External pyramidal - layer III
Internal granular - layer IV
Internal pyramidal - layer V
Multiform (fusiform) - layer VI
Molecular (plexiform) - layer I lies directly beneath what?
the pia matter
Molecular (plexiform) - layer I
contains which cell types?
Horizontal cells of Cajal-Retzius
External granular - layer II
Cell types?
Mostly stellate cells and some small pyramidal cells
External pyramidal - layer III
cell types?
Pyramidal cells
Internal granular - layer IV
Whats special about this area?
Main cortical input station
Specially developed within the sensory areas
Internal granular - layer IV
Cell types?
Mostly stellate cells and a smaller portion of pyramidal cells
Internal pyramidal - layer V
Cell types
Medium and large pyramidal cells
Internal pyramidal - layer V
Whats special about this area?
Main cortical output station (corticofugal fibres)
Most prominent within the motor cortex
The primary motor cortex contains large Betz cells
Multiform (fusiform) - layer VI
Cell types
Mostly fusiform cells, with less dominant pyramidal cells and interneurons
PHYLOGENETIC CORTEX
Name the phylogenetic cortexes
- Allocortex:
- Archicortex
- Paleocortex - Mesocortex
- Neocortex
Allocortex is phylogenetically old, comprises as few as 3 layers (up to 5 layers)
The allocortex further subdivides into:
Archicortex
Paleocortex
Archicortex (ancient cortex: eg, hippocampus)
Consists of only three cellular layers: polymorphic, pyramidal and the molecular
It is associated with the limbic system, specifically with the hippocampal formation, meaning it is involved with emotional expression and memory
Paleocortex – younger than archicortex
Consist of three to six layers
Located within the parahippocampal gyrus (entorhinal cortex), uncus (piriform cortex) and lateral olfactory gyrus, meaning it mediates the sense of smell
Mesocortex
Represents transitional cortex between neocortex and allocortex Contains three to six layers
Comprises the cingulate gyrus and the remainder of the
parahippocampal gyrus
Neocortex (aka isocortex)
Is phylogenetically new, and comprises six histologically distinct layers
It constitutes roughly 90% of the cerebral cortex
FUNCTIONAL ORGANIZATION
Posterior cerebrum
Medial limbic
Anterior cerebrum
Areas of association cortex in frontal, parietal and temporal lobes of the left hemisphere are responsible for the
comprehension and expression of language
