External Oblique
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The largest, most superficial flat abdominal; flexes the trunk and rotates it toward the opposite side.
Detail
The external oblique is the largest and most superficial of the 3 flat abdominal muscles. When both sides work together, trunk flexion occurs. If only one side contracts, the trunk will flex toward the opposite side (i.e., when only the right side contracts, the external oblique twists the trunk to the left). Note the "oblique" arrangement of its fibers.
Key facts
- Largest and most superficial of the 3 flat abdominal muscles.
- Both sides together: trunk flexion.
- One side only: twists the trunk toward the opposite side (right contraction → twist left).
- Oblique fiber arrangement.
Connections
- Abdominals (Midsection) — group it belongs to.
- Internal Oblique — paired in rotation.
- Transverse Abdominis — deeper flat abdominal.
- Side Bends / Trunk Twists (Rotary Torso) — training exercises.
Sources
Exercise guides
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Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.