<prompt> The shortest diameter of fetal head is:Biparietal diameterSuboccipitofrontal diameterOccipitofrontal diameterBitemporal diameter  <response>: Ans. is d, i.e. Bitemporal diameterRef. Dutta Obs. 9e. p 11MnemonicRemember Friends: always transverse diameters of the fetal skull are smaller than Anteroposterior diameters.Amongst the given options: Biparietal and bitemporal diameters are transverse diameters, whereas suboccipitofrontal and occipitofrontal are anteroposterior diameters.Now, the choice is between bitemporal and biparietal diameters.For memorizing this: learn a mnemonic, where transverse diameter are arranged in ascending order of their size.Miss Bimastoid diameter 7.5 cmTina Bitemporal diameter 8 cmS Super subparietal diameter 8.5 cmPretty Biparietal diameter 9.5 cmSo, our answer is bitemporal diameter 8 cmRemember:In AP diameters:The longest AP diameter of fetal skull is mentovertical diameter 14 cmThe second longest AP diameter is submentovertical Occipitofrontal 11.5 cm. 