Anatomy: Low Back

Low Back Muscles

MuscleAttachementNerve SupplyAction
Erector SpinaeO: Broad tendon from iliac crest, posterior surface of sacrum, sacro-iliac ligaments
I: Illiocostalis – superiorly to angles of lower ribs to transverse processes of cervical vertebrae
Longissimus- superiorly to ribs between tubercles and transverse processes in thoracic and cervical regions and to mastoid process
Spinalis – superiorly to spinous processess in upper thoracic region to cranium
Posterior rami of spinal nerves– Extends vertebral column
– laterally flex vertebral column
MultifidusO: Posterior sacrum, posterior superior iliac spine of ilium, S.I ligaments
I: Obliquely, superomedially to lamina and transverse process or spinous process of vertebrae 2 segments superior
Posterior Rami of spinal nerves– Stabilizes vertebrae during local movements of spinal column
Quadratus LumborumO: Inferior border of 12th rib and tips of L1-L5 transverse processes
I: Iliolumbar ligament and internal lip of iliac crest
Anterior branches of T12 and L1- L4 nerves– Extends vertebral column
– Laterally flexes vertebral column

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