The major and minor psoas muscles and the iliacus muscle make up the iliopsoas musculotendinous unit (IPMU). Commonly called iliopsoas muscle. This complex muscle system can function as a unit or intervene as separate muscles. It is essential for correct standing or sitting lumbar posture, stabilizing the coxofemoral joint, and is crucial during walking and running. The fascia covering the iliopsoas muscle creates multiple fascial connections, relating the muscle to different viscera and muscle areas. Several disorders can affect IPMU at the level of its insertion (tendon) or involving the fleshy part. To solve these dysfunctions, the doctor will indicate which therapy will be most useful, conservative or surgical, as well as physiotherapy or an osteopathic approach. There are multiple anatomical variations of IPMU, and in case of pain and disturbances, it is important to perform instrumental examinations before making a precise diagnosis. With the current scientific knowledge, one can not imagine anatomy as segments but rather as a functional continuum.