- a series of pairs of muscles of small muscles extending the full length
of the spine just superficial to the rotators and each spanning 2 or 3
intervertebral spaces before inserting;
origin: posterior surface of the sacrum, the dorsal end of the iliac
crest, the transverse processes of the lumbar and the thoracic
vertebrae and the articular processes of the 4th to the 7th
vertebrae;
insertion: spinous processes of all the vertebrae except the atlas;
action: acting unilaterally, lateral flexion and rotation to the
opposite side; acting bilaterally, extension and hyperextension
of the spine;
nerve supply: posterior rami of the spinal nerves;
synergists: rotators,
Interspinales ,
[
Intertransversarii
groups;
