Quadratus Lumborum, Psoas, & Iliacus Muscles

Illustration from 'Surgical Anatomy: The Treatise of the Human Anatomy and Its Applications to the Practice of Medicine and Surgery, volume III' (by Dr. John Blair Deaver) shows the quadrus lumborum muscle, a thin, quadrilateral muscle, 1903. It arises two inches beyond the inner lip of the crest of the ilium, near the junction of its middle and posterior thirds, from the ilio-lumbar ligament, and from the tips of the trnsverse processes of the lower three lumbar vertebrae. The psoas muscle is a fusiform muscle which arises by five fasciculi from the transverse processes of all the bodies of the vertebrae between the lower margin of the last thoracic vertebrae and the upper margin of the last lumbar vertebrae inclusive. The Iliacus muscle is wide and triangular. . (Photo by VintageMedStock/Getty Images)