Patients with lower back pain often have tightness of the hip flexor muscles. This is aggravated by the presence of a forward bent posture from lower back pain and presence of weak and shortened paraspinal muscles. This places the abdominal wall and the hip flexor muscles in an advantageous position to bring the trunk and hips into flexion.
The hip flexor muscle tightness is favored by the presence of weakness of the hip extensor muscles such as the gluteus maximus, adductor magnus and the hamstring muscles. Muscles that perform hip flexion are:
- Iliopsoas
- rectus femoris
- sartorius
- pectineus
These muscles are supplied by the femoral nerve (L2, L3 and L4 spinal nerve roots).
Muscles that also perform hip flexion are:
- gluteus medius and minimus
- tensor fascia latae
- adductor longus and brevis
The gluteus medius and minimus (L5, S1 spinal nerve roots) and tensor fascia latae (L4, L5 spinal nerve roots) are supplied by the superior gluteal nerve.
Adductor longus and brevis are applied by the obturator nerve (L2, L3 and L4 spinal nerve roots).