The thoracolumbar fascia: anatomy, function and clinical considerations.
The thoracolumbar fascia (TLF) consists of both aponeurotic as well as fascial connective tissue. Its most important functions are providing a retinaculum for paraspinal musculature in the lumbar region and an insertion site for a substantial amount of trunk and extremity muscles. Through these attachments, muscles and passive tissues are able to exert moments and reaction forces on the TLF, essentially providing stability in several degrees of freedom of the lumbar spine.
There are several anatomical models available for the TLF, of which the two-layer model and the three-layer model are most common – in the majority of recent publications however, the three-layer model is adopted. The posterior layer contains two laminae; superficial (also the aponeurosis of the latissimus dorsi) and deep. Together with the deep lamina, the middle layer forms an envelope for the iliocostalis, longissimus and multifidus, and the erector spinae – this is referred to as the paraspinal reticular sheath. Laterally, the sheath forms a raphe that joins with the aponeurosis of the transversus abdominis. Anterior to the middle layer, the quadratus lumborum is situated, which is separated from the psoas by the anterior layer, that courses between them.
In the lower lumbal region, all of the layers fuse into the massive thoracolumbar composite, which is strongly connected to the posterior superior iliac spine and the sacrotuberous ligament. > From: Willard et al., J Anat 221 (2012) 507-536. All rights reserved to The Authors.
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