Lumbar fascia Lumbar fascia The lumbar fascia is an anatomic structure of the lumbar region. It consists of a band or sheet of connective tissue fibres, primarily collagen, that attaches, stabilizes, encloses and separates muscles not limited to the lumbar region as the name suggests, but extending upwards over the thorax to the neck and downwards over the muscles covering the sacrum. The upper thoracic portion is thin while the lumbar and sacral regions are thicker and stronger. The lumbar fascia binds the deep muscles of the back to the spine and to the transverse processes of the vertebrae. Additionally the lumbar
Interstitium Interstitium The interstitium is a contiguous fluid-filled space existing between a structural barrier, such as a cell wall or the skin, and internal structures, such as organs, including muscles and the circulatory system. The fluid in this space is called "interstitial fluid", comprises water and solutes, and drains into the lymph system. The interstitial compartment is composed of connective and supporting tissues within the body – called the extracellular matrix – that are situated outside the blood and lymphatic vessels and the parenchyma of organs. The non-fluid parts of the interstitium are predominantly collagen types I, III, and V, elastin,