origin: transverse processes of the 1st to 5th thoracic vertebrae and the
articular processes of the 4th to 7th cervical vertebrae;
insertion: the posterior margin of the mastoid process;
action: acting bilaterally, extends and hyperextends head; acting
unilaterally, flexes and rotates the head the same side;
synergists:
Semispinalis capitis , spinalis capitis,
Longissimus Cervicis ;
