The deep muscles of the back are divided in 3 layers: superficial layer, intermediate layer, and deep layer, which additionally can be divided into two more - the deep and deepest layers. Each layer contains specific muscles listed below.

Superficial layer:

• Splenius capitis
• Splenius cervicis

Intermediate layer:

Erector spinae, consisting of:

• Iliocostalis
  • Iliocostalis cervicis
  • Iliocostalis thoracis
  • Iliocostalis lumborum
• Longissimus
  • Longissimus capitis
  • Longissimus cervicis
  • Longissimus thoracis
• Spinalis
  • Spinalis capitis
  • Spinalis cervicis
  • Spinalis thoracis

Deep layer:

• Rotatores spinae
• Multifidus
  • Cervical multifidus
  • Thoracic multifidus
  • Lumbar multifidus
• Semispinalis
  • Semispinalis capitis
  • Semispinalis cervicis
  • Semispinalis thoracis

Deepest layer:

• Interspinales
  • Interspinales cervicis
  • Interspinales thoracis
  • Interspinales lumborum
• Intertransversarii
  • Intertransversarii cervicis
  • Intertransversarii lumborum
• Levatores costarum