A line about which something rotates. The reference axes for human movement are vertical, sagittal, and frontal.

A line about which something rotates. The reference axes for human movement are vertical, sagittal, and frontal.

• A. Angulation
• B. Axis
• C. Alignment
• D. Apex

Answer: (B)

Rotations in the body happen around an axis, which is the line about which movement turns. In human movement we describe three main axes: vertical, sagittal, and frontal. The axis defines the actual line of rotation, so you can picture twisting around the vertical axis (like turning your torso), or bending around the sagittal axis (flexion/extension in the sagittal plane), or moving away from or toward the body around the frontal axis (abduction/adduction in the frontal plane). The other terms don’t describe the rotating line: angulation refers to a bend angle between segments, alignment is about position relative to a reference, and apex is simply the tip.

Rotations in the body happen around an axis, which is the line about which movement turns. In human movement we describe three main axes: vertical, sagittal, and frontal. The axis defines the actual line of rotation, so you can picture twisting around the vertical axis (like turning your torso), or bending around the sagittal axis (flexion/extension in the sagittal plane), or moving away from or toward the body around the frontal axis (abduction/adduction in the frontal plane). The other terms don’t describe the rotating line: angulation refers to a bend angle between segments, alignment is about position relative to a reference, and apex is simply the tip.