Strongest flexor of the hip joint is:
Iliopsoas is the chief Flexor at hip joint, assisted by Saorius and Pectineus as the accessory muscles. Gluteus Maximus is the chief Extensor at hip joint, assisted by hamstrings as the accessory muscles.
Saorius
Gluteus maximus
Iliopsoas
Pectineus
Muscles of Lower Limb