This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
The engaging diameters of the fetal skull depends on the degree of flexion present. Which is the longest diameter of fetal skull? 
Select and explain. 
A. Submento-bregmatic, B. Mento veical, C. Sub Occipito frontal, D. Occipito frontal
B: Mento veical
Answer: B: Mento veical 
Explanation: Mento-veical diameter is 14 cm which extends from the midpoint of the chin to the highest point on the sagittal suture. Must know: Submento-bregmatic diameter is 9.5 cm which extends from junction of floor of the mouth and neck to the centre of the bregma. Sub Occipito frontal diameter is 10 cm which extends from the nape of the neck to the anterior end of the anterior fontanelle or the centre of the sinciput. Occipito frontal diameter is 11.5 cm. It extends from the occipital eminence to the root of the nose (glabella). Ref: Textbook of Obstetrics by D C Dutta, 6th edition, Page 85.