Description: Segment 1 The intertitles explain that the mechanism of labour is mainly concerned with the movements of the foetus' head trying to accommodate itself to the pelvic canal. Four types of movements are described: 'descent', 'internal rotation', 'actual birth of the head' and 'external rotation of the head'. These four types of movement are then demonstrated with a model pelvis and skull, with views shown from in front and from below. Time start: 00:00:00:00 Time end: 00:04:23:23 Length: 00:04:23:23