The tiny gaps between adjacent schwann cells are called

Answer;

Nodes of Ranvier

Explanation;Nodes of Ranvier are the spaces between the myelin coating on the neuron's axon. Nodes of Ranvier have space exposed to conduct electricity with the environment to propagate the signal down the axon.At the nodes of Ranvier, electricity can be conducted within the cell's environment, and the electrical signal will be propagated down the axon.

The answer would be sand and gravel