Spinalis Thoracis

Origin: the spinous process of the 1st and 2nd lumbar vertebrae, the
        thoracic vertebrae 10, 11, 12;
insertion: the spinous process of the thoracic vertebrae 3-8 and
            sometimes 9;
action: acting unilaterally, lateral flexion of the spine; acting
        bilaterally, extension and hyperextension of the spine;
nerve supply: posterior rami of the spinal nerves;
synergists:   Semispinalis Thoracis ,   Longissimus Thoracis , iliocostalis
            thoracis,   i1lioCost8LUMB5[Iliocostalis Lumborum , longissimus thoracis,
            Quadratus Lumborum;

Original Text by Clifford R. Wheeless, III, MD.