The muscle responsible for trunk flexion with rotation to the left on a fixed pelvis is?

• A. Right External Oblique
• B. Left Internal Oblique
• C. Rectus Abdominis
• D. Transverse Abdominis

Answer: (B)

The muscle that is primarily responsible for trunk flexion with rotation to the left on a fixed pelvis is the Left Internal Oblique. When the left internal oblique contracts, it works to rotate the trunk towards the left side while simultaneously contributing to flexion. The internal oblique muscle fibers run diagonally, allowing for this rotational movement along with flexion.

In this scenario, the pelvis is fixed, which means that the rotation is occurring at the trunk. The left internal oblique assists in bringing the left shoulder towards the pelvis and rotating the torso accordingly. This muscle has a crucial role in activities that involve bending and twisting the trunk, making it essential for certain functional movements and sports performance.

Understanding the action of the internal obliques can facilitate better training and rehabilitation strategies, especially in contexts where trunk stability and control are important.