Pertaining to the structure of a head that has a narrow cranium as compared with the width of the face, so that when the skull is seen from above, the zygomatic arches are visible, that means that the bones form a bridge between the cheekbones and the temporal bones on each side of the bony skeleton of the head of vertebrates: In her biology book for school, it was interesting to see a photo of a skull that had a phenozygous form.