The prerequisites for internal rotation of the head are all except
The shape of pelvic floor: Two halves of levator ani form a gutter and viewed from above the direction of fibers is backward and towards the midline. Elastic recoil of the levator ani occurs bringing the occiput forwards towards the midline.Pelvic shape: forward inclination of the side walls of the cavity, narrow bispinous diameter and long anteroposterior diameter of outlet pulls long axis of the head to accommodate in maximum available diameter,Well flexed headEfficient uterine contractionMid-pelvic plane shapeThe tone of levator ani musclesD.C.DUTTA&;S TEXTBOOK OF OBSTETRICS, Pg no:125, 7th edition
Well flexed head
Efficient uterine contraction
Favourable shape of the pelvis
Tone of the abdominal muscles
General obstetrics