Psoas Minor, Gross Anatomy

Description

Arising from the lateral surfaces of T12 to L1 and the intervening intervertebral disc, the psoas minor appears as a slender, fusiform muscle belly positioned anterior to the psoas major and closely applied to the anterior lumbar vertebral bodies. Its long tendon descends inferiorly along the medial margin of psoas major toward the pelvic brim, blending with the iliopsoas (psoas) fascia and inserting on the iliopubic eminence and pecten pubis, just superior and medial to the acetabulum. Posterior to both psoas muscles, the lumbar vertebrae and discs provide the osseous reference, while the iliac crests and superior pelvic ring frame the inferior field. Fascial planes are emphasized, including the psoas fascia as it continues into the iliac fascia over iliacus. For teaching, this is the cleanest way to separate psoas minor from psoas major, a distinction that is easy to lose once you move laterally into the iliac fossa or inferiorly toward the lesser trochanter. Clinically, the psoas fascia forms part of the posterior boundary of the retroperitoneum and guides spread of a psoas abscess, which can track inferiorly toward the groin and present with hip flexion contracture. The muscle itself is variably present, and its tendon can be a landmark when discussing pelvic brim anatomy and femoral nerve proximity on the anterior surface of psoas major. Use this artwork in gross anatomy lab manuals, musculoskeletal modules on hip flexors and lumbar stabilizers, and surgical education content covering retroperitoneal approaches to the lumbar spine and lumbosacral junction where psoas and its fascia must be respected. Anatomical accuracy verified by SciePro's Medical Advisory Board.