The thoracolumbar fascia is the portion of the deep fascia of the trunk covering the erector spinae muscle in the thoracic and lumbar region.
It attaches to the spinous processes of the thoracic, lumbar and sacral vertebrae, the supraspinous ligament, the sacral tuberosity, the iliac crest and the coxal tuberosity. Cranioventrally, it continues as the axillar fascia, caudally as the gluteal fascia and ventrally as the abdominal tunic..
The thoracolumbar fascia may be divided in different layers, varying between authors and not included in the NAV. In major sources, two layers are described (three are listed in human):