Nerves that run up and down the length of the back and transmit most messages between the body and brain are the ______.

Nerves that run up and down the length of the back and transmit most messages between the body and brain are the ______.

• A. Spinal cord
• B. Brain
• C. Peripheral nerves
• D. Nerve endings

Answer: (A)

The main idea here is identifying the central nervous system structure that carries most messages between the brain and the rest of the body. The description fits the spinal cord: a long bundle of nerve tissue that runs inside the vertebral column along the back and acts as the main highway for information passing between the brain and body. It receives sensory signals from the body and sends motor commands from the brain, using ascending and descending nerve pathways. It also handles many reflex actions without involving the brain. Think about the other options: the brain stays in the head as the control center, not a long cord running along the back. Peripheral nerves are the network that branches out from the spinal cord and brain to reach limbs and organs; they don’t form a single continuous cord along the back. Nerve endings are the tiny sensory receptors at the ends of nerves, not a long transmitting channel.

The main idea here is identifying the central nervous system structure that carries most messages between the brain and the rest of the body. The description fits the spinal cord: a long bundle of nerve tissue that runs inside the vertebral column along the back and acts as the main highway for information passing between the brain and body. It receives sensory signals from the body and sends motor commands from the brain, using ascending and descending nerve pathways. It also handles many reflex actions without involving the brain.

Think about the other options: the brain stays in the head as the control center, not a long cord running along the back. Peripheral nerves are the network that branches out from the spinal cord and brain to reach limbs and organs; they don’t form a single continuous cord along the back. Nerve endings are the tiny sensory receptors at the ends of nerves, not a long transmitting channel.