Module 2 BBB Cardinal Movements Flashcards
Cardinal movements generally occur as a result of force from above and resistance from below; give examples:
Above examples: contractions, pushing, gravity
Blow example: tissue, muscles, bony pelvis
What are the seven cardinal movements?
Engagement
Descent
Flexion
Internal Rotation
Extension
Restitution
External Rotation
Explain Descent
Descent occurs throughout labor and, therefore, is requisite to and occurs simultaneously with the other cardinal movements. Descent is the result of contractions and maternal pushing efforts during the second stage.
Broken down: the baby moving down the pelvis.
Explain Flexion
Flexion is essential to further descent once engagement has occurred. During this third cardinal movement, the smaller suboccipitobregmatic diameter becomes the widest fetal head diameter that traverses the maternal pelvis. When the fetal head is flexed so that the fetal chin rests on the thorax, the suboccipitobregmatic is substituted for the larger fetal head diameters that exist when the fetal head is not completely flexed, is in a military attitude, or is in some degree of extension. Flexion occurs when the fetal head meets resistance; this resistance increases with descent and is first met from the cervix, then from the sidewalls of the pelvis, and finally from the pelvic floor. Some degree of flexion, therefore, may occur prior to engagement.
Broken down: Baby putting its chin to its chest (makes a smaller diameter)
Explain Engagement
Engagement occurs when the biparietal diameter of the fetal head has passed through the pelvic inlet.
Broken down: When the head is low in the pelvis (at the level of the pelvic inlet or below)
(Remember that there are two different ways to define engagement. One definition using the BPD as the reference point, the other uses the top of the head. Engaged= BPD has passed through the inlet (cannot feel this clinically via vaginal exam) ALSO=top of the head at the level of the ischial spines (can feel clinically via vaginal exam)
Explain Internal Rotation
Internal rotation brings the anteroposterior diameter of the fetal head into alignment with the anteroposterior diameter of the maternal pelvis. Most commonly, the occiput rotates to the anterior portion of the maternal pelvis, beneath the symphysis pubis. If internal rotation has not occurred by the time the fetal head has reached the pelvic floor, it takes place shortly thereafter.
Broken down: where the baby’s head turns so it can fit through the pelvis at or below the s. pubis. We can sometimes see this happening during pushing.
Explain Extension
Birth of the head occurs by extension (of the fetal head so the chin lifts up from the thorax) in occiput anterior births. This cardinal movement of labor is different when the occiput rotates to an occiput posterior (OP) position.
Broken down: the baby lifts its chin off its chest to fit the rest of the head out (like a NIKE swoosh)
Explain Restitution
Internal rotation brings the anteroposterior diameter of the fetal head into alignment with the anteroposterior diameter of the maternal pelvis. Most commonly, the occiput rotates to the anterior portion of the maternal pelvis, beneath the symphysis pubis. If internal rotation has not occurred by the time the fetal head has reached the pelvic floor, it takes place shortly thereafter.
Broken down: After the head is delivered, it rotates back to the same direction as the shoulders (they did not turn during internal rotation)
Explain External Rotation
External rotation occurs as the fetus’s shoulders rotate 45 degrees, bringing the bisacromial diameter into alignment with the anteroposterior diameter of the pelvic outlet. This causes the head to rotate externally another 45 degrees into the LOT or ROT position, depending on the direction of restitution.
Broken Down: the shoulder rotate like the head did so they can also deliver.
What is the difference between restitution and external rotation?
Restitution is the baby’s head realigning with the body. External rotation is the shoulders turning so they can also deliver. They often occur so quickly that is hard to tell the difference.
How are the cardinal movements different for an OP position?
Head must flex rather than extend to negotiate the curve
How are the cardinal movements different for an OP position?
Head must flex rather than extend to negotiate the curve
What is the cardinal movement that occurs throughout labor?
Descent
What cardinal movement does this describe? When the biparietal diameter reaches the pelvic inlet.
Engagement
What cardinal movement occurs at the mid-plane of the pelvis?
Internal rotation
