Musculus psoas major, also known as musculus psoas magnus, is a major muscle located in the human body. It is classified as a long fusiform muscle that belongs to the iliopsoas group. The psoas major originates from the lumbar vertebrae, specifically the sides of the vertebral bodies and intervertebral discs of the 12th thoracic vertebrae to the fifth lumbar vertebrae. From its origin, the muscle descends along the sides of the lumbar spine, crossing the pelvic region.
The muscle gradually widens as it descends, forming a thick and powerful tendon that unites with the iliacus muscle, forming the iliopsoas muscle. This combined tendon inserts into the lesser trochanter, which is a bony prominence on the femur. Functionally, the musculus psoas major is responsible for flexing the hip joint, providing support to the lumbar spine, and assisting with lateral flexion of the trunk.
The psoas major muscle plays a crucial role in various movements and postures, including walking, running, and sitting. It allows for the lifting of the thigh towards the trunk, as well as the extension and external rotation of the hip joint. Additionally, this muscle aids in maintaining stability and balance during activities that require core strength.
In summary, the musculus psoas major or magnus is a significant muscle located in the lumbar region of the human body, responsible for hip flexion, support of the lumbar spine, and aiding in trunk movement.
