Psoas Major Muscle, Gross Anatomy

Description

Running vertically along the posterior abdominal wall, the paired psoas major muscles flank the lumbar vertebral bodies and intervertebral discs, then descend inferolaterally toward the pelvis to merge with the iliacus in the iliac fossa. Medial fibers arise from the sides of T12 to L5 vertebrae, with slips associated with the transverse processes, while the muscle belly lies anterior to the lumbar spine and medial to the iliacus. Distally, the iliopsoas tendon courses deep to the inguinal region and attaches to the lesser trochanter of the femur. Red highlighting isolates iliacus and psoas major against a grayscale scaffold of ribs, pelvis, and adjacent trunk and hip musculature. Clear landmarks. For teaching and clinical planning, this anatomy matters because the psoas major defines a corridor used in lateral lumbar approaches (including transpsoas interbody fusion), where the lumbar plexus travels within and along the posterior portion of the muscle belly and is vulnerable during dilation and retraction. Inflammatory or infectious pathology can also track within the psoas compartment, and a psoas abscess may present with hip flexion pain because iliopsoas contraction and stretch irritate the involved fascia. The insertion on the lesser trochanter explains why iliopsoas tendinopathy and snapping hip symptoms localize to the anterior hip and worsen with resisted hip flexion. Use this plate in gross anatomy labs, musculoskeletal modules, and surgical education materials that need a clean read of iliopsoas origins, course, and femoral insertion, with enough bony context to orient learners quickly. It also fits well in clinical handouts on hip flexor strain, lumbar plexus risk in spine surgery, and psoas abscess recognition. Anatomical accuracy verified by SciePro's Medical Advisory Board.