The muscles on either side are arranged in five superimposed layers.
- First layer
- Trapezius thoracis
- Latissimus dorsi
- Second Layer
- Rhomboideus thoracis
- Third Layer
- Serratus dorsalis anterior
- Serratus dorsalis posterior
- Fourth Layer
- Longissimus costarum
- Longissimus dorsi
- Fifth Layer
- Levatores costarum
- Multifidus dorsi
- Intertransversales lumborum
