<prompt> Flexors of lumbar spine are all EXCEPT:Erector spinaeExternal oblique muscleInternal oblique muscleRectus abdominis  <response>: Forward flexors: Rectus abdominis, external abdominal oblique, internal abdominal obliques, transversus abdominis and iliacus-psoas. Lateral flexors: Ipsilateral contraction of the oblique and transversus abdominal muscles and quadratus lumborum. 