Grey and white matter, falx and tentorium

Grey matter contains a high density of neuronal cell bodies. White matter consists of axons and their associated glial cells. My paired sketches show how their arrangement changes between the cerebral cortex and spinal cord.

In the cerebral hemispheres, the cortex is an outer layer of grey matter, with white matter beneath it. In the spinal cord, grey matter forms the central butterfly, surrounded by white matter. The cortical pattern is not a rule for the whole brain. In the brainstem, grey nuclei sit among tracts of white matter.

The lower sketch is a memory map of connective sheets. The falx cerebri separates the two cerebral hemispheres. The tentorium cerebelli separates the cerebellum from the cerebrum. Their membranous parts are dural folds that help limit brain movement within the skull. The sketch does not show every part of the tentorium or provide a complete anatomical view.

References

Johnston & Tobias, 2nd ed., Ch29, Anatomy.