The oblique muscles are part of a group of muscles called “abdominal muscles”. You have four abdominal muscles, the most known is the rectus abdominis, the middle (washboard?) muscle and the whole group are often referred to as just “abs”. There’s the transverses abdominis, which lie along side the rectus abdomenis, and then the pair of muscles called the obliques. Obliques are located on each of the sides of your torso. External obliques are large, thin muscles on top and internal obliques are triangle shaped muscles just underneath the external obliques.
You know the drill: crunches, leg extensions, barbell rollouts, chops, planks, twists, rows, sit-ups, and deadlifts. All those exercises move you toward a goal of washboard abs. But well-defined abs aren’t the same as having a strong core.
Your “core” is really a group of muscles in your lower back, stomach and hips. Basically, all the muscles you have that are not in your arms and legs. Their function is to keep the spine stable and the body upright. They help bending, rotation, and twisting and are involved in just about every moment you do.