Psoas Major

Description

Arising from the anterolateral surfaces of the lumbar vertebral bodies and adjacent intervertebral discs, the psoas major descends inferiorly along the pelvic brim, lying anterior to the transverse processes and lateral to the vertebral midline. Its fibers run deep to the abdominal viscera and pass toward the lesser trochanter of the femur, where the tendon merges with the iliacus to form the iliopsoas. The iliacus occupies the iliac fossa, lateral to psoas major, and both muscles converge medial to the anterior inferior iliac spine as they course toward the hip joint. Lumbar vertebrae L1 through L5 and their discs provide the proximal attachment field, with the pelvis and proximal femur anchoring the distal relationship. Understanding the psoas major in this deep anterior compartment matters because its intimate contact with the lumbar spine and hip makes it a common generator of combined low back and anterior groin pain, and a frequent culprit in hip flexion contracture that increases lumbar lordosis. Surgeons and proceduralists track its medial border when approaching the lumbar spine and retroperitoneum, and sports clinicians watch the iliopsoas tendon as it passes anterior to the hip capsule, a typical site of snapping hip and iliopsoas tendinopathy. Short. The depiction of vertebral body and disc attachments also supports teaching of psoas-related infection pathways, including psoas abscess tracking from spondylodiscitis. Use this artwork for gross anatomy teaching of the posterior abdominal wall, for orthopedic and sports medicine chapters on iliopsoas strain and internal snapping hip, and for spine content explaining anterior approaches at the lumbar levels and their relationship to the psoas corridor. Anatomical accuracy verified by SciePro's Medical Advisory Board.