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Abdominal obliques
Two crossing layers on the side of the abdomen that rotate and side-bend the trunk, and resist it being twisted.
Latin name: Musculi obliquus externus et internus abdominis. In plain English, the side abdominal muscles that twist the trunk. It is filed here under core, breathing and pelvic floor.
Reference information, not a diagnosis. Where a symptom is described below, it is there so you can describe your own more precisely to a clinician — not so you can name what you have.
Where it is
The two oblique layers run at right angles to each other, like the plies of a tyre. The external oblique fibres slope downward and forward — the direction your fingers point when you put your hands in your front pockets. The internal oblique, lying underneath, runs the other way, upward and forward. Both end in broad aponeuroses that contribute to the rectus sheath and meet at the linea alba in the midline.
Their lower borders form some important structures: the free lower edge of the external oblique aponeurosis makes the inguinal ligament, and the internal oblique and transversus contribute the conjoint tendon behind the inguinal canal. This region is where inguinal hernias occur.
| Feature | Detail |
|---|---|
| External oblique | From the outer surfaces of ribs five to twelve, fibres running down and forward, to the iliac crest and the linea alba; rotates the trunk to the opposite side |
| Internal oblique | From the thoracolumbar fascia, iliac crest and lateral inguinal ligament, fibres running up and forward, to ribs ten to twelve and the linea alba; rotates the trunk to the same side |
| Nerve | Thoracoabdominal nerves T7-T12, with L1 fibres to the internal oblique |
| Main actions | Trunk rotation and side flexion, compression of the abdomen, and resisting rotation under load |
What it does
Rotation is a partnership: the external oblique of one side works with the internal oblique of the other. Turning your trunk to the left uses the right external oblique and the left internal oblique together. That crossing pattern is why rotational power in throwing, striking and swinging comes from the whole trunk diagonally rather than from one side.
In everyday movement their bigger job is resisting rotation. Carrying a weight in one hand, walking, running, and pushing something one-handed all try to twist the trunk, and the obliques stop it. They also work with the diaphragm, transversus abdominis and pelvic floor to raise abdominal pressure for a heavy lift, a cough or a forced breath out.
Exercises that load it
| Exercise | Category | Muscles the exercise library lists |
|---|---|---|
| Plank | Core | Deep core, shoulders, glutes |
| Mountain climbers | Conditioning | Core, hip flexors, shoulders |
| Farmer's carry | Strength | Grip, core, upper back, legs |
| Kettlebell swing | Conditioning | Glutes, hamstrings, back, core |
| Burpees | Conditioning | Whole body |
Side planks and single-sided carries load them isometrically in the anti-rotation and anti-side-bend role, which is what they mostly do in life. Rotational work — chops, throws, rotational medicine ball work — loads them concentrically. Because the fibres cross, both sides should get equal work even in sports that are heavily one-sided.
How it is lengthened
Side-bend away from the side being stretched with the arm reaching overhead, then add a gentle rotation. A lying trunk twist with the knees dropping to one side and the opposite shoulder staying down does the same thing with the spine supported. Keep it comfortable; forcing rotation at end range loads the lumbar facet joints rather than the muscle.
When it goes wrong
| Problem | What it typically feels like | Usual setting |
|---|---|---|
| Oblique strain | A sharp pain in the side of the abdomen on twisting, coughing or sneezing | Rotational sport — throwing, bat and racquet sports, or a sudden violent twist |
| Inguinal hernia | A soft bulge in the groin that appears on standing or straining and disappears when lying down, sometimes with a dragging ache | A weakness in the abdominal wall in the inguinal region; more common in men |
| Rib cartilage irritation | Pain at the lower rib margin on twisting or deep breathing, tender to press | After a strong rotational effort or a direct blow |
A groin or abdominal bulge that becomes painful, firm, and cannot be pushed back in, especially with vomiting, is a surgical emergency — a strangulated hernia. Go to hospital rather than waiting.
Nothing on this page is a treatment plan. If a problem is limiting what you do, is not improving, or is getting worse, the right next step is an assessment by a doctor or a physiotherapist who can examine you.
Sources: descriptive anatomy from Gray's Anatomy of the Human Body, 20th US edition (1918), which is in the public domain; Latin names follow Terminologia Anatomica, published by the Federative International Programme for Anatomical Terminology. Nerve root levels are the conventional ranges taught from those sources and vary between individuals and between textbooks. Exercise cross-links use the TempoLife exercise library. Checked 2026-09-06.
Frequently asked questions
Which oblique turns me to the left?
The right external oblique together with the left internal oblique. Rotation is always produced by the external oblique of one side and the internal oblique of the other working as a pair.
Do side bends give you a wider waist?
Training the obliques makes them stronger and slightly thicker, but the visible width of a waist is dominated by skeletal proportions and body fat. The effect of side bends on waist appearance is small.
Why do the obliques hurt after a coughing illness?
Coughing is a violent, repeated abdominal contraction. After days of it, the abdominal wall behaves like any muscle that has done an unfamiliar amount of work.
Nearby in this reference
Rectus abdominis
The straight abdominal muscle, the six-pack
Transversus abdominis
The deepest abdominal layer, a corset around the waist
Diaphragm
The dome of muscle that does your breathing
Pelvic floor
The sling of muscle at the base of the pelvis
Deltoid
The cap of the shoulder
Rotator cuff
The four small muscles that hold the shoulder in its socket
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