Answer:
These group of muscles called erector spinae muscles arises from a tendon in the sacral area and pelvis, it extends up to the occipital bone.
Erector spinae muscles originates from the SPINOUS PROCESSES of T9-T12 of the thoracic vertebrae and inserts into the SPINOUS PROCESSES of T1-T2 of the cervical vertebrae
They therefore run vertically on either side of the spine (medially and laterally).
