Which structure increases the speed of nerve impulse transmission?

The myelin sheath is crucial in increasing the speed of nerve impulse transmission. It is a fatty layer that surrounds the axon, acting as an insulator. This insulation allows electrical impulses to jump between the nodes of Ranvier (gaps in the myelin along the axon), significantly increasing the speed and efficiency of signal transmission.

In contrast, dendrites are responsible for receiving incoming signals from other neurons but do not directly influence the speed of transmission. The axon is the structure that conducts impulses away from the neuron's cell body, but without the myelin sheath, the impulses would travel much slower. A neuron refers to the entire nerve cell itself, which includes the axon and dendrites, but again does not specifically denote the enhanced speed that myelin provides.