Final answer:
The psoas major muscle does indeed flex the hip joint, forming the iliopsoas with iliacus, and is significant in activities that require hip flexion.
Step-by-step explanation:
The statement that the psoas major muscle flexes the hip joint is true. The psoas major, along with the iliacus, forms the iliopsoas, which is a key muscle group in the hip flexion movement. In addition to the iliopsoas, the pelvic girdle region also includes large and powerful muscles such as the gluteal muscles which are primarily responsible for extending and abducting the femur. However, the iliopsoas is particularly important for hip flexion, which involves bringing the thigh closer to the abdomen. This muscle group plays a crucial role in various activities that require hip flexion, including walking, running, and climbing.
Other muscles in the gluteal region such as the gluteus maximus, medius, and minimus are mainly involved in extending and abducting the femur. Nonetheless, the iliopsoas is the primary muscle group that functions to flex the thigh at the hip. Hence, when discussing movements at the hip joint and the muscles responsible for these actions, the psoas major, as part of the iliopsoas, is rightly considered a hip flexor