origin: C7 and T1-T6 thoracic transverse processes and articular processes of 4th, 5th, and 6th cervical vertebrae;
insertion: between superior and inferior nuchal lines of the occipital;
action: extnesion of lateral flexion of the neck and head, and rotates it to the opposite side;
nerve supply: posterior rami of the cervial nerves;
synergists: splenius group,  Semispinalis Cervicis