Iliocostalis is a term used in anatomy and refers to a group of muscles in the human body. These muscles are located in the back and are responsible for extending the spine. There are two other synonyms, which include the longissimus thoracis muscle and the spinal nerve. The longissimus thoracis muscle is also located in the back and is responsible for extending the spine, just like the iliocostalis. The spinal nerve, on the other hand, is a type of nerve that runs through the spine and controls the muscles in the back. These synonyms for iliocostalis are useful for medical professionals to describe the back muscles and the tasks they perform.