Which muscle lies internal to the external oblique and also compresses the abdomen?

• A. Internal Oblique
• B. External Oblique
• C. Transversus Abdominis
• D. Rectus Abdominis

Answer: (A)

Think of the abdominal wall as layered from outside to inside: external oblique on the surface, then the internal oblique just beneath it, followed by deeper muscles. The muscle that sits directly internal to the external oblique is the internal oblique, and that placement fits the clue about being beneath the external oblique. It also compresses the abdomen by increasing intra-abdominal pressure, helping to support and stabilize the abdominal contents during movement and coughing or lifting. The other options don’t match both ideas as neatly: the external oblique is the outermost layer, the rectus abdominis runs along the midline rather than beneath the external oblique, and while the transversus abdominis also compresses the abdomen, it lies deeper than the internal oblique, not directly internal to the external oblique.