Summary Iliacus Origin Upper 2/3 of iliac fossa, internal lip of iliac crest, lateral aspect of sacrum, ventral sacroiliac ligament, and lower portion of iliolumbar ligament Insertion Lesser trochanter Action Flex the torso and thigh with respect to each other Innervation Muscular branch of femoral nerve (L1, L2, L3) Arterial Supply Lumbar branch of iliopsoas branch of internal iliac artery