Gaps in the myelin sheath are known as Nodes of Ranvier. These structures are found at regular intervals along myelinated axons in the nervous system. The myelin sheath is a fatty layer that insulates axons, allowing for faster transmission of electrical impulses (action potentials) along the nerve fibers.
The nodes play a critical role in a process called saltatory conduction, where the action potential jumps from one node to the next. This mechanism significantly increases the speed of conduction as compared to unmyelinated axons, where the impulse travels along the entire length of the membrane.
In summary, the gaps in the myelin sheath, or Nodes of Ranvier, are essential for efficient nerve signal propagation in myelinated axons.