Myel refers to the fatty substance that forms a protective covering around nerve fibers, also known as myelin. Synonyms for myel include medullary sheath, neurolemma, and neurilemma. The medullary sheath is the outermost layer of the myelin sheath that surrounds nerve fibers, providing a protective barrier. The neurolemma is the cell membrane that surrounds the axons of nerve cells, contributing to the formation of myelin. Lastly, the neurilemma is a layer of cells that encloses nerve fibers, covering the Schwann cells and aiding in the creation of the myelin sheath. Understanding the various synonyms for myel helps to enhance our understanding of the complex structure and functionality of nerve cells in our bodies.