Answer
Superficial erector spinae muscle:
Location: Area of middle back in sheath of quadratus lumborum
Action: Aids in sitting and in standing erect. Straightens back after bending at the waist; also achs back; unilateral contraction flexes waist laterally.
Origin: Nuchal ligaments; ribs 3-12; thoracic and lumbar vertebrae, medial and lateral sacral crests and thoracolumbar fascia.
Insertion: Mastoid process, cervical and thoracic vertebrae and all ribs
Innervation: Posterior rami of cervical and lumbar spinal nerves.
Work Step by Step
The erector spinae group of muscles extends vertically on each sides of the vertebral column from occipital bone to pelvis and sacrum.The group includes iliocostalis, longissimus, spinalis, semispinalis, rotatores, interspinales and intertransversarii muscles. The superficial group is comprised of the thoracic parts of the longissimus thoracis, and the iliocostalis lumborum plus the associated spinal aponeurosis.
