The upper erector spinae consist of the thoracic fibres of iliocostalis lumborum and longissimus thoracis.
The lumbar fibres of iliocostalis lumborum and longissimus thoracis are more angulated relative to the vertebral column than the multifidus or the upper erector spinae, with a substantial increase in obliquity towards the L4-L5 region (Macintosh and Bogduk 1991).
Differences in electromyographic activity in the multifidus muscle and the iliocostalis lumborum
between healty subjects and patients with sub-acute and chronic low back pain.
1997) demonstrated that the multifidus has more activity than the iliocostalis lumborum
during Biering-Sorensen testing.
Although some authors do mention the presence of lumbar muscles and fascia, specifi cally the quadratus lumborum, multifi dus and iliocostalis lumborum
(Collee et al.