You are utilizing a counterstrain technique to treat your 54 year old patient's piriformis muscle. Which of the following statements about the piriformis muscle is true?
A) The piriformis muscle originates from the anterior surface of the sacrum.
B) The piriformis muscle is innervated by the femoral nerve.
C) The piriformis muscle primarily acts as a flexor of the hip joint.
D) The piriformis muscle plays a role in external rotation of the hip joint.