In human anatomy, the hip flexors are a group of skeletal muscles that act to flex the femur onto the lumbo-pelvic complex, i.e. "pull the knee upward".

The hip flexors are considered to be the most important muscle in the running process.

The hip flexors are (in order of importance to the action of flexing the hip joint):

• Collectively known as the Iliopsoas or inner hip muscles:
• Psoas major
• Psoas minor
• Iliacus muscle

• Anterior compartment of thigh
• Rectus femoris. (Part of the Quadriceps.)
• Sartorius

• One of the gluteal muscles:
• Tensor fasciae latae

• Medial compartment of thigh
• Pectineus
• Adductor longus
• Adductor brevis
• Gracilis

Without the iliopsoas muscles, flexion in sitting position is not possible across the horizontal plane.

Notes

References

• Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol 1: Locomotor system. 5th, Thieme. (ISBN for the Americas 1-58890-159-9.)