Psoas Minor

Description

Arising from the bodies of T12 and L1 and the intervening intervertebral disc, the psoas minor appears as a slender, sometimes absent muscle belly on the anterior surface of psoas major within the retroperitoneal space of an adult male. Its tendon descends inferiorly and slightly medial to the psoas major fibers, crossing the pelvic brim toward the iliopectineal eminence and pectineal line (often blending with the iliac fascia). Laterally, iliacus fills the iliac fossa and joins psoas major to form the iliopsoas as it passes anterior to the hip joint toward the lesser trochanter. A thin muscle. Variable by nature. Recognition of psoas minor matters because it is a frequent anatomic variant that can confuse dissection, operative exposure, and cross sectional interpretation when a narrow tendon is seen anterior to psoas major near the pelvic brim. Surgeons approaching the lumbar spine or retroperitoneum (for example, anterior lumbar interbody fusion or lateral transpsoas approaches) use the iliopsoas complex as a landmark, and an unexpected psoas minor tendon can be mistaken for iliopsoas fascia or a fibrous band when mobilizing the psoas major. In teaching, it also reinforces that psoas major is the dominant hip flexor, while psoas minor, when present, contributes mainly to weak lumbar flexion and fascial tensioning rather than meaningful hip movement. Ideal placement includes gross anatomy labs covering posterior abdominal wall and pelvis, physical therapy and sports medicine modules on hip flexor anatomy, and surgical atlases discussing retroperitoneal corridors around the lumbar vertebrae and pelvic brim. Medical publishers will also find it useful for chapters on anatomic variation and for clarifying the relationship of psoas major to the lumbar spine, pelvis, and hip joint in male anatomy. Anatomical accuracy verified by SciePro's Medical Advisory Board.