Which substance contains insulating myelin coatings and is found in the spinal cord?

The correct choice refers to white matter, which is primarily composed of myelinated axons that form the insulated pathways for electrical signals traveling through the spinal cord and the brain. The presence of myelin around these axons is crucial for the efficient conduction of nerve impulses, as it acts as an insulating layer that improves the speed and efficiency of neuron communication.

In contrast, gray matter primarily consists of neuronal cell bodies, dendrites, and unmyelinated axons, playing a significant role in processing information and integrating signals. The meninges are protective membranes surrounding the brain and spinal cord and do not contain myelin or nerve fibers themselves. The parietal lobes are regions of the cerebral cortex involved in sensory perception, not specific to the structure of the spinal cord.