sphingomyelin is a type of phospholipid found in cell membranes, particularly in the membranes of nerve cells. It plays a crucial role in maintaining the structure and function of these membranes, contributing to their stability and fluidity. This lipid is composed of a sphingosine backbone, a fatty acid, and a phosphate group, which is often linked to a choline molecule. Sphingomyelin is important for the formation of myelin, the protective sheath around nerve fibers, which facilitates efficient signal transmission in the nervous system.