What does the central nervous system primarily consist of?

The central nervous system (CNS) is primarily composed of the brain and spinal cord, which are crucial for processing information and transmitting signals throughout the body. The brain serves as the control center, managing and interpreting sensory data, coordinating motor functions, and facilitating cognitive tasks such as thinking and memory. The spinal cord acts as a pathway for messages between the brain and the rest of the body, enabling reflex actions and maintaining communication between the CNS and peripheral nervous system. This structure is essential for overall bodily function and responsiveness to stimuli.

In contrast, the other options refer to components that are part of the nervous system but do not encapsulate its central aspect. Nerves and ganglia are elements of the peripheral nervous system rather than the CNS. Muscles and tissues pertain to the muscular and connective systems of the body, not the nervous system itself. Peripheral nerves and sensory receptors are outside the CNS and are involved in relaying information to and from the CNS, but they do not constitute the central nervous system itself.