Anatomy
Origin:
Transverse processes of L3 to L5, iliolumbar ligament and iliac crest.
Insertion:
Inferior border of 12th rib and transverse processes of L1 to L3.
Key relations:
-Quadratus lumborum lies deep to the colon, kidney, psoas major, psoas minor and the diaphragm.
-The subcostal, iliohypogastric and ilioinguinal nerveslie anterior to the fascia that overlies quadratus lumborum.
Functions
-Depresses and stabilizes the 12th rib.
-Lateral flexion of the vertebral column (trunk) e.g. bending sideways to pick something up.
-Contracting bilaterally aid in extension of the lumbar part of the vertebral column (trunk).
Supply
Nerve Supply:
Anterior rami of T12 and L1 to L4 spinal nerves.
Blood Supply:
-Lumbar arteries
-Lumbar branch of iliolumbar artery.
Clinical
The spine has a natural curve which is necessary in order for it to function properly. Exaggeration of the curve increases pressure on other parts of the spine resulting in pain.
Lordosis or hyperlordosis is an exaggerated curve in the lumbar region of the spine. Lordosis may be caused by tightness and weakness of the muscles surrounding the hip and the spine resulting in an imbalance. Tightened muscles require stretching while weakened muscles require strengthening. Muscles commonly tightened include trunk extensors e.g. quadratus lumborum and erector spinae muscles and hip flexors e.g. iliopsoas. Muscles commonly weakened include abdominal muscles e.g. rectus abdominis and external obliques and hip extensors e.g. gluteus maximus and the hamstrings.
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