Biology · Neural Control and Coordination · NEET
The cerebral cortex is grey matter. NCERT says the cortex is the layer of cells covering the cerebral hemisphere and is 'referred to as the grey matter due to its greyish appearance.' The white matter is a separate, deeper region.
Grey matter looks greyish because neuron cell bodies are concentrated there. White matter looks white and opaque because it is made of nerve fibres covered with the myelin sheath. So: cell bodies = grey, myelinated fibres = white.
The white matter forms the inner part of the cerebral hemisphere, lying below the cortex. It is made of the fibre tracts whose fibres are covered with myelin sheath, giving the opaque white appearance.
The cerebral cortex contains motor areas, sensory areas, and large regions that are neither clearly sensory nor motor. These in-between regions are the association areas, responsible for complex functions like intersensory associations, memory and communication.
NCERT states the cortex is 'thrown into prominent folds.' The folding increases the surface area so more neuron cell bodies can fit into the skull. More cortical surface means more processing capacity.
In the cerebrum, grey matter (cortex) is on the outside and white matter is inside. Note this is the opposite arrangement compared to the spinal cord, where grey matter is inside and white matter is outside. This reversal is a common NEET trap.
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It is the layer of cells covering the cerebral hemisphere, packed with neuron cell bodies, which is why it is called grey matter.
Grey matter (cortex, outer) has concentrated neuron cell bodies; white matter (inner) is made of myelinated nerve fibres. Grey looks greyish, white looks opaque white.
They are cortex regions that are neither clearly sensory nor motor, and they handle complex functions like intersensory associations, memory and communication.
The myelin sheath covering the nerve fibres of the tracts gives white matter its opaque white appearance.
Each cerebral hemisphere is covered by cortex. The two hemispheres themselves are joined by a fibre tract called the corpus callosum.
