Which motion is the x-axis responsible for?

Which motion is the x-axis responsible for?

• A. Rotation
• B. Flexion and Extension
• C. Lateral Bend
• D. Abduction

Answer: (B)

Flexion and extension are forward-and-back bends that occur when a segment rotates about a side-to-side axis. The x-axis runs from one side of the body to the other, so rotations around it move structures in the sagittal plane, producing flexion (forward bending) and extension (backward straightening). Lateral bending moves the body to the side and involves a different axis, while abduction is movement away from the midline in another plane, again governed by a different axis. So the x-axis best accounts for flexion and extension.

Flexion and extension are forward-and-back bends that occur when a segment rotates about a side-to-side axis. The x-axis runs from one side of the body to the other, so rotations around it move structures in the sagittal plane, producing flexion (forward bending) and extension (backward straightening). Lateral bending moves the body to the side and involves a different axis, while abduction is movement away from the midline in another plane, again governed by a different axis. So the x-axis best accounts for flexion and extension.