Which of the following causes flexion of the lumbar spine?
Flexion of lumbar spine is caused by bilateral action of the rectus abdominis and psoas major. Gravity may also play a role. Bilateral action of the erector spinae, multifidus and semispinalis thoracis cause extension of the lumbar spine. Unilateral action of the external oblique, internal oblique, longissimus thoracis, multifidus, quadratus lumborum, rhomboids, serratus anterior, iliocostalis and lumborum results in lateral bending.Also know:Unilateral action of rotators, multifidus, iliocostalis, longissimus, external oblique acting synchronously with opposite internal oblique and splenius cervicis.
Erector spinae
External obliques muscle
Internal oblique muscle
Psoas major