The psoas
Psoas major · musculus psoas major
A long, deep muscle linking your lower spine to your thigh, the main hip flexor.
What it does
The psoas major starts on the sides of the lumbar vertebrae, runs down through the pelvis and joins the iliacus to attach to the inside of the femur. Together they lift the thigh towards the chest, as when you climb stairs or march, and help sit you up from lying down.
Surprising fact
The psoas is the cut of meat sold as fillet or tenderloin, because in animals it does very little work and so stays especially tender.
Why it matters
Sitting for hours keeps the hip flexors in a shortened position, which some people feel as tightness at the front of the hip when they stand up straight.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.