Psoas Major - Podcast Version 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The psoas major is a muscle of the posterior abdominal wall. It is a long, thick muscle located immediately lateral to the lumbar vertebrae. It combines with the iliacus muscle to form the iliopsoas – the major flexor of the thigh at the hip joint. Attachments: Originates from the transverse processes and vertebral bodies of T12 – L5. It then moves inferiorly and laterally, running deep to the inguinal ligament, and attaching to the lesser trochanter of the femur. Actions: Flexion of the thigh at the hip and lateral flexion of the vertebral column. Innervation: Anterior rami of L1 – L3 nerves. Blood supply: Lumbar branch of iliolumbar artery. By TeachMeSeries Ltd (2026) Fig 1Muscles of the posterior abdominal wall. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Pro Feature - Dissection Atlas The lumbar plexus, femoral nerve and muscles of the posterior abdominal wall. The lumbar plexus, femoral nerve and muscles of the posterior abdominal wall. You've Discovered a Pro Feature Access our Dissection Image Library Enhance your understanding with high-resolution dissection images showcasing real-life anatomy. Learn More Frequent questions What is the psoas major muscle? The psoas major is a significant muscle located in the posterior abdominal wall, positioned laterally to the lumbar vertebrae. It works in conjunction with the iliacus muscle to form the iliopsoas, which is the primary flexor of the thigh at the hip joint. What are the attachments of the psoas major? The psoas major originates from the transverse processes and vertebral bodies of the T12 to L5 lumbar vertebrae. It extends inferiorly and laterally, passing beneath the inguinal ligament to attach at the lesser trochanter of the femur. What actions does the psoas major perform? The psoas major primarily facilitates the flexion of the thigh at the hip joint. Additionally, it contributes to the lateral flexion of the vertebral column. How is the psoas major innervated? The psoas major is innervated by the anterior rami of the L1 to L3 spinal nerves. This nerve supply is crucial for the muscle's function in hip flexion and spinal movement. What is the blood supply to the psoas major? The blood supply to the psoas major muscle comes from the lumbar branch of the iliolumbar artery. This vascular supply is essential for maintaining the muscle's health and functionality. Rate This Article