The shoest diameter of fetal head :
Bitemporal and biparietal diameters are transverse diameters whereas suboccipitofrontal and occipitofrontal are the anteroposterior diameters Bitemporal diameter is 8 cm Ref: Datta Obs 9e pg 77.
Biparietal diameter
Suboccipitofrontal diameter
Occipitofrontal diameter
Bitemporal diameter
General obstetrics