The iliopsoas muscle flexes your hip, bends your trunk towards your thigh and rotates your thigh bone. It’s made up of two muscles — the psoas and iliacus. These muscles run from the lower spine and pelvis, join together, then attach by a tendon to the upper thigh. This tendon can get irritated from overuse, muscle weakness and muscle tightness, causing tenderness and pain. https://www.webmd.com/fitness-exercise/features/hip-tendonitis#1
