Myo-inositol is one of eight naturally occurring forms that make up the nutrient inositol. Each one has a slightly different shape and are individually referred to as isomers. The myo-inositol isomer is the most abundant form found in the central nervous system, where it can be converted into phosphatidyl inositol, a second messenger neurotransmitters. Inositol is the term used to describe the entire group of isomers together.