The divisions of the combatant primarily concern the middle or handwork phase of the fight. The divisions are quite trivial so Meyer actually spends most of chapter 1 talking about why he isn’t going to talking about it.
Of the body the divisions are upper-left, upper-right, lower-left, and lower-right. Likewise the head is divided into the four quarters with the nose as the center-point. The head is called out separately because much of the handwork endeavors to strike it.