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The posterior regions of the abdomen, composed between the base of the chest and the pelvis. The parts which enter into the formation of the lumbar region are,-the skin; a considerable quantity of areolar texture; broad and strong aponeuroses: - the Latissimus Dorsi, Obliquus externus, and Obliquus internus abdominis, Transversalis abdominis, Quadratus lumborum, and the mass common to the Sacro-lumbalis, Longissimus dorsi, and Multifidus spinae. These muscles surround the lumbar region of the vertebral column. The vessels, nerves, etc., of the loins, are called lumbar.