Your abdominal muscles contain three layers of muscles on the side. The middle layer is the _____?

• A. Rectus abdominis
• B. There are only 2 layers.
• C. Internal oblique
• D. External oblique

Answer: (C)

The side wall of the abdomen has three flat muscle layers layered from outside to inside: the outermost is the external oblique, the middle is the internal oblique, and the deepest is the transversus abdominis. The rectus abdominis is the vertical muscle along the front midline, not part of these lateral layers.

The middle layer being the internal oblique fits the anatomy because its fibers run in a different direction from the external oblique, helping with trunk rotation and lateral bending and contributing to overall abdominal containment and pressure. This arrangement of layers allows coordinated movement and stability of the torso while protecting the internal organs.