What is the thin outer covering of grey matter covering each cerebral hemisphere of the brain known as?

The thin outer covering of grey matter that envelops each cerebral hemisphere of the brain is called the cerebral cortex. This structure plays a critical role in various high-level brain functions, including sensory perception, cognition, motor control, and the processing of complex information. The cerebral cortex is divided into different regions that are associated with specific functions, such as the frontal, parietal, temporal, and occipital lobes.

The grey matter consists primarily of neuronal cell bodies, which are essential for processing information, while the underlying white matter contains myelinated axons that facilitate communication between different areas of the brain. Understanding the role of the cerebral cortex in brain function helps in studying how various cognitive processes are regulated and how they can be affected in neurological disorders.

The other options refer to different structures that do not represent the outer layer of the cerebral hemispheres. White matter, for instance, pertains to the myelinated axons that connect various brain regions, rather than the grey matter surface. Medullary sheath typically refers to the protective covering around nerve fibers, and subcortex designates structures located beneath the cortex, involved in other functions distinct from those of the cerebral cortex.