The correct term for the relationship between the sternum and the arm is ‘medial.’ The sternum, or breastbone, is located at the center of the chest and is considered a medial structure, while the arms are positioned laterally on either side of the body.
To elaborate, in anatomical terms, ‘medial’ refers to a position closer to the midline of the body, while ‘lateral’ describes something that is further away from the midline. Therefore, when we say the sternum is medial compared to the arms, we highlight the relative positions of these structures in relation to each other.