Deep and deepest deep back muscles (English)

The deep and deepest layers of the deep back muscles consist of several smaller muscle groups. Broken down simply, the deep layer consists of a muscle group called transversospinal muscles, subdivided into the semispinalis, multifidus and rotatores muscles. These subgroups are further broken down into regional components, with the exception of the rotatores that are divided based on their length into the short and long rotatores breves and longi.The deepest layer consists of three muscle groups: levatores costarum, interspinales and intertransversarii muscles. They are often referred to as the segmental or minor back muscles given their small size and limited role in the back movements.