Iliopsoas
The iliopsoas muscle refers to the joined psoas major and the iliacus muscles. The two muscles are separate in the abdomen, but usually merge in the thigh. They are usually given the common name iliopsoas. The iliopsoas muscle joins to the femur at the lesser trochanter. It acts as the strongest flexor of the hip.
The iliopsoas muscle is supplied by the lumbar spinal nerves L1-L3 and parts of the femoral nerve.
Structure
The iliopsoas muscle is a composite muscle formed from the psoas major muscle, and the iliacus muscle. The psoas major originates along the outer surfaces of the vertebral bodies of T12 and L1-L3 and their associated intervertebral discs. The iliacus originates in the iliac fossa of the pelvis.The psoas major unites with the iliacus at the level of the inguinal ligament. It crosses the hip joint to insert on the lesser trochanter of the femur. The iliopsoas is classified as an "anterior hip muscle" or "inner hip muscle". The psoas minor does contribute to the iliopsoas muscle.
The inferior portion below the inguinal ligament forms part of the floor of the femoral triangle.
Nerve supply
The psoas major is innervated by direct branches of the anterior rami of the lumbar plexus at the levels of L1-L3, while the iliacus is innervated by the femoral nerve.Function
The iliopsoas is the prime mover of hip flexion, and is the strongest of the hip flexors. The iliopsoas is important for standing, walking, and running. The iliacus and psoas major perform different actions when postural changes occur.The iliopsoas muscle is covered by the iliac fascia, which begins as a strong tube-shaped psoas fascia, which surround the psoas major muscle as it passes under the medial arcuate ligament. Together with the iliac fascia, it continues down to the inguinal ligament where it forms the iliopectineal arch which separates the muscular and vascular lacunae.