Final answer:
In the spinal cord, gray matter forms a central butterfly-shaped region surrounded by white matter in columns. The gray matter processes and relays information, while white matter transmits nerve signals. The orientation in the brain is converse, with gray matter on the outside and white matter internally.
Step-by-step explanation:
The spinal cord and the brain have distinct orientations for their white matter and gray matter. In the spinal cord, a cross-section reveals a butterfly-shape of gray matter at the center, surrounded by white matter in columns.
The gray matter consists primarily of neuron cell bodies including interneurons and motor neurons, while white matter is made up of myelinated axons that form part of the central nervous system (CNS). The gray matter is involved in processing and relaying information, whereas white matter facilitates the transmission of nerve signals.
White matter is organized into columns that can be seen longitudinally along the spinal cord: posterior (dorsal), anterior, and lateral columns. The posterior columns are made up of ascending axons carrying sensory information to the brain.
The anterior and lateral columns contain both ascending and descending axons, the latter transmitting motor commands from the brain to the spinal cord to control various bodily functions. Contrary to the spinal cord, the brain's gray matter typically resides on the outside in the form of cortical areas, and the white matter is internal, allowing for communication between different brain regions and the rest of the CNS.