What term describes the spinal movement during a side flexion from the right side while in a supine position with knees bent?

The term that accurately describes the spinal movement during a side flexion from the right side while in a supine position with knees bent is unilateral flexion. This is because side flexion involves bending the spine to one side, which is considered unilateral movement. In this case, flexing to the right side specifically means that only one side of the spine is experiencing flexion, differentiating it from bilateral movements where both sides of the body engage equally.

Unilateral flexion typically engages specific muscles on one side, such as the obliques and the quadratus lumborum, while stabilizing muscles on the opposite side. This term precisely reflects the nature of the motion, emphasizing the targeted contraction on one side of the body as opposed to a symmetrical motion.

Other terms such as rotation, which involves twisting around the spinal axis, or extension, which denotes a straightening of the spine, do not apply to this scenario. Likewise, bilateral flexion would imply that both sides of the spine are flexing simultaneously, which is not the case when focusing solely on the right side during this specific movement in a supine position.