Describe the mechanisms of labor, including extension of the head, restitution, internal rotation of the shoulders, external rotation of the head, birth of the shoulders, and delivery of the rest of t

Here is the information from the table regarding the mechanisms of labor:

• Extension of the head

  • The final head becomes extended on the neck releasing the sinciput, face and chin.
  • The head is delivered by a movement of extension.

• Restitution

  • Restitution is the untwisting of the twist in the fetal neck.
  • The twist occurred during internal rotation of the neck.

• Internal rotation of the shoulders

  • The anterior shoulder reaches the pelvic floor first and rotates anteriorly to lie under the symphysis pubis.

• External rotation of the head

  • At the same time the internal rotation of the shoulders takes place, the external rotation of the head also takes place.
  • When the shoulders turn one-eighth of a circle, the head also turns one-eighth of a circle in the same direction.

• Birth of the shoulders

  • The anterior shoulder slips under the pubic arch while the posterior shoulder sweeps the perineum, reducing the size of the presenting diameter.
  • The shoulders are born by a movement of lateral flexion.

• Delivery of the rest of the body

  • With the same contraction and continuing movements of lateral flexion, the rest of the body is born by lateral flexion.