Lumborum is a Latin word that refers to the lower back muscles. There are several synonymous terms to describe lumborum that can be used interchangeably. These include the erector spinae, the longissimus muscle, the spinalis muscle, and the transversospinalis muscle. The erector spinae is a group of muscles that runs parallel to the spine, the transversospinalis muscle is a smaller group of muscles that attaches to the transverse processes, and the spinalis muscle is a group of muscles that runs up the spine. Knowing these synonyms can help you better understand anatomy and improve communication with medical professionals.