During elbow flexion, the forearm moves around which axis?

During elbow flexion, the forearm primarily rotates around the X axis. This is because flexion at the elbow joint occurs in the sagittal plane, which is defined as the plane that divides the body into left and right halves. The axis of motion in this plane is the X axis, which runs from side to side (or medial to lateral) across the body.

As the forearm moves towards the shoulder during flexion, it pivots around this horizontal axis, allowing for an increase in the angle between the forearm and the upper arm. This rotation is essential for various activities involving the arm, such as lifting or bringing objects closer to the body. Understanding this axis of movement is crucial in biomechanics as it highlights the relationship between joint movement and the planes of motion, which is fundamental for analyzing human movement and designing rehabilitation or training programs.