External oblique
Obliquus externus abdominis
Pronunciation: eks-TER-nal oh-BLEEK
For beginners
These are the muscles on the sides of your waist that let you twist your torso and bend sideways — think of reaching down to the side, or a baseball swing.
Show the advanced explanation
The external oblique on one side works with the internal oblique on the opposite side as a functional pair to rotate the trunk — rotation is always a cross-body team effort, not one muscle alone.
Structure & function
- Location
- The most superficial ab muscle on the side of the abdomen, with fibers running diagonally down and inward, like hands in front pockets.
- Origin
- Lower eight ribs.
- Insertion
- Iliac crest and the linea alba (abdominal midline).
- Main action(s)
- Flexes and laterally flexes the trunk; rotates the trunk to the OPPOSITE side when acting alone; with the internal oblique of the other side, produces trunk rotation.
- Joint(s) crossed
- Intervertebral joints of the lumbar and lower thoracic spine
- Movement plane
- transverse (rotation); frontal (lateral flexion)
- Innervation
- Intercostal nerves (T7–T12) and the iliohypogastric/ilioinguinal nerves
- In daily movement
- Twisting the torso, such as looking over a shoulder or a golf/throwing-style rotation.
- In exercise
- Prime mover (with the opposite internal oblique) in rotational exercises like the Russian twist or cable woodchop.
- Commonly confused with
- Its rotation direction is a common point of confusion: the external oblique on the right side helps rotate the trunk to the LEFT, not the right.
- Common misconceptions
- Doing many side-bends will not 'slim the waist' — spot reduction is not possible, and heavy loaded side-bends mainly build the muscle, not remove fat over it.
Exercises that use this muscle
As a primary mover
As a secondary / stabilizer
- Plank (secondary)
- Dead Bug (secondary)
- Neutral spine hold (posture reset) (secondary)
- Cat-cow stretch (secondary)
⚠ Safety note
Forceful, uncontrolled twisting under heavy load can strain the obliques; build rotational strength gradually.
Sources
“The external oblique flexes and rotates the vertebral column, rotating the trunk to the opposite side.”
Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.3 Axial Muscles of the Abdominal Wall, and Thorax
Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19
Sign in to bookmark this and save notes.