The oblique muscle refers to two paired abdominal muscles, the external and internal obliques, that provide trunk flexion and rotation. The external oblique muscle is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen, extending from the lower half of the ribs around and down to the pelvis. The external oblique muscle is situated on the lateral and anterior parts of the abdomen, and its muscular portion occupies the side, while its aponeurosis covers the anterior wall of the abdomen. The external oblique muscle controls bending physical activities such as bending over, twisting the torso, side bending, and assists with breathing. It also performs ipsilateral (same side) side-bending and contralateral (opposite side) rotation. The internal oblique muscle is located underneath the external obliques on each side of the trunk. The internal obliques originate on the inguinal ligament, which is a ligament that runs from the anterior iliac spine to the pubic bone. The internal obliques can function bilaterally, which means both sides working together, and unilaterally, which means one-sided. When acting unilaterally and in synergy with the contralateral internal abdominal oblique, it rotates the trunk to the opposite side. Working together with the ipsilateral abdominal and back muscles, it contributes to trunk flexion and compression of its contents.