Gynaecology & Obstetrics The engaging diameters of the fetal skull depends on the degree of flexion present. Which is the longest diameter of fetal skull? A Submento-bregmatic B Mento veical C Sub Occipito frontal D Occipito frontal 💡 Explanation The engaging diameters of the fetal skull depends on the degree of flexion present. Which is the longest diameter of fetal skull? ✓ Correct Answer: B. Mento veical