anatomy/hip-flexors·Muscle
Hip flexors
Musculus iliopsoas
The strongest hip flexor. It is the only muscle that directly connects the spine to the leg, and it lifts the knee.
// Structure & location
The iliopsoas consists of two muscles. The psoas major arises from the lumbar vertebrae, the iliacus from the inner surface of the pelvic wing. Both pass together under the inguinal ligament to the lesser trochanter on the inside of the femur. It lies deep and can't be seen from outside.
// Function
It flexes the hip, lifting the knee forward and up, and raises the upper body from lying down. According to OpenStax it also helps with bending over and maintaining posture.
// For training & sport
- Hanging leg raises, knee raises and sprints train it hard.
- In sit-ups (not crunches) it works strongly, because the upper body is raised all the way to the thighs.
- To stretch it, use a deep lunge and push the hip of the back leg forward.
// Good to know
Because it pulls on the lumbar vertebrae, strong contraction can pull the lower back into an arch if the abs don't hold against it.
// Sources
last reviewed: 2026-11-14
// More from the atlas: Muscles
Pectoralis majorDeltoidBicepsTricepsForearm musclesRectus abdominisObliquesSerratus anteriorQuadricepsAdductorsTibialis anteriorTrapeziusLatissimus dorsiErector spinaeGluteus maximusHamstringsCalves