National Physical Therapy Examination (NPTE) Practice Exam

Which muscle group is primarily responsible for hip flexion?

1. Quadriceps

2. Hamstrings

3. Iliopsoas

4. Gluteus maximus

The correct answer is: Iliopsoas

The iliopsoas muscle group is primarily responsible for hip flexion due to its anatomical placement and function. This group consists of two main muscles: the psoas major and the iliacus. Together, they originate from the lumbar spine and the iliac fossa of the pelvis, respectively, and they insert into the lesser trochanter of the femur. When the iliopsoas contracts, it pulls the femur towards the pelvis, effectively flexing the hip joint. While other muscle groups, such as the quadriceps, hamstrings, and gluteus maximus, play roles in movements around the hip, they are not primarily responsible for hip flexion. The quadriceps are primarily involved in knee extension, the hamstrings contribute to hip extension and knee flexion, and the gluteus maximus is chiefly responsible for hip extension and external rotation. Thus, the iliopsoas is the key muscle group that facilitates the action of bringing the thigh forward, making it critical for tasks such as walking, running, and climbing.