Cardinal Movements at Birth
The Seven Cardinal Movements=======================Labor is a physical and emotional event for the laboring woman. For the infant, however, there are many positional changes that assist the baby in the passage through the birth canal. Because of the resistance met by the baby, positional changes are specific, deliberate and precise as they allow the smallest diameter of the baby to pass through a correspondingdiameter of the woman's pelvic structure. Neither careproviders nor the laboring woman is directly responsible for these position changes. The baby is the one responsible for these position changes ~ the cardinal movements.Engagement or the entering of the biparietal diameter(measuring ear tip to ear tip across the top of the baby's head) into the pelvic inlet.DescentThe baby's head moves deep into the pelvic cavity and is commonly called lightening. The baby's head becomes markedlymolded when these distances are closely the same. When the occiput is at the level of the ischial spines, it can be assumed that the biparietal diameter is engaged and then descends into the pelvic inlet.FlexionThis movement occurs during descent and is brought about by the resistance felt by the baby's head against the soft tissues of the pelvis. The resistance brings about a flexion in the baby's head so that the chin meets the chest. The smallest diameter of the baby's head (orsuboccipitobregmatic plane) presents into the pelvis.Internal rotationAs the head reaches the pelvic floor, it typically rotates to accommodate for the change in diameters of the pelvis. At the pelvic inlet, the diameter of the pelvis is widest from right to left. At the pelvic outlet, the diameter is widest from front to back. So the baby must move from a sideways position to one where the sagittal suture is in the anteroposterior diameter of the outlet (where the face of the baby is against the back of the laboring woman and the back of the baby's head is against the front of the pelvis). If anterior rotation does not occur, the occiput (or head) rotates to the occipitoposterior position. The ocipitoposterior position is also called persistent occipitoposterior and is the common cause for true back labor.ExtensionAfter internal rotation is complete and the head passes through the pelvis at the nape of the neck, a rest occurs as the neck is under the pubic arch. Extension occurs as the head, face and chin are born.