What term divides the body into right and left sides?

• A. Midline
• B. Medial
• C. Proximal
• D. Posterior

Answer: (A)

This question hinges on understanding the reference line that splits the body into right and left sides. The midline is the imaginary line running down the center of the body, defining the sagittal plane that divides the body into left and right halves. Saying something is medial means it is toward this line, while lateral would be away from it.

Proximal describes closeness to the trunk or origin, and posterior describes the back side, neither of which defines the right–left split. So the term that designates the division into right and left is the midline.