What cell structure is responsible for the insulation of nerve fibers?

The myelin sheath is the key cell structure responsible for the insulation of nerve fibers. It is a fatty layer that surrounds the axons of many neurons, significantly enhancing the speed and efficiency of electrical signal transmission. This insulating layer prevents the loss of electrical signal and allows the nerve impulse to travel faster by jumping between the nodes of Ranvier, small gaps in the myelin sheath. This process is referred to as saltatory conduction and is crucial for rapid communication in the nervous system.

Other structures mentioned serve different functions; dendrites are responsible for receiving signals from other neurons, axon terminals release neurotransmitters to communicate with other cells, and the soma (cell body) contains the nucleus and is vital for the maintenance and function of the neuron. Thus, the myelin sheath stands out specifically for its insulating role in nerve fibers.