Two sets of muscles are involved in extension of the spine: a deep spinal group and a superficial spinal group. The deep spinal muscle group is comprised of the intertransversarii, interspinalis, rotatores and multifidus muscles, which are very small and run in pairs. These muscles join the transverse and spinous processes of adjacent vertebrae. They play an important role in holding the vertebrae and discs in place as well as in moving the spine.
Origin
Most often they attach only to the vertebra next to them but some may extend over 2-3 vertebrae.
Insertion
Most often they attach only to the vertebra next to them but some may extend over 2-3 vertebrae.
Function
They play a role in holding the vetebrae and discs in place, as well as moving the spine.
