vertex
From ZooTerms (Dictionary of Invertebrate Zoology)
apex; summit; the highest or principal point.
vertex (noun; Latin vertex, top): 1. The top;
2. (Arthropoda: Crustacea) The top point of the head or cephalon.
3. (Arthropoda: Insecta) The top of the head, between the eyes and anterior to the occipital suture; the crown of the head.