What are the primary transmission lines of the nervous system that help make up nerves?

The primary transmission lines of the nervous system that make up nerves are axons. Axons are long, slender projections of a neuron that carry electrical impulses away from the neuron's cell body toward other neurons, muscles, or glands. Each nerve is composed of many axons bundled together, allowing for the efficient transmission of signals across various parts of the body.

Dendrites are another part of the neuron, responsible for receiving incoming signals from other neurons. While they play a crucial role in neurotransmission, they do not transmit signals away from the neuron and therefore are not considered transmission lines.

Neurons themselves are the basic functional unit of the nervous system that includes dendrites, axons, and cell bodies but do not refer specifically to the structures that conduct impulses.

The neuromuscular junction, on the other hand, is a specific site where a motor neuron communicates with a muscle fiber. While important for muscle contraction, it is not a structure that comprises the transmission lines of nerves.

Thus, the axon is the correct answer as it represents the primary structure responsible for signal transmission in the nervous system.