Which layer of the uterus is responsible for contractions during childbirth?

The myometrium is the middle layer of the uterine wall and is primarily composed of smooth muscle tissue. This muscle layer plays a critical role during childbirth, as its contractions help to expel the fetus from the uterus. The rhythmic contractions of the myometrium are essential for labor, facilitating the process of pushing the baby through the birth canal. The strength and coordination of these contractions are crucial for an effective delivery.

In contrast, the endometrium is the innermost layer, which is primarily involved in the menstrual cycle and the implantation of a fertilized egg but does not contribute to the contractions during childbirth. The perimetrium is the outer layer that provides additional support but is not involved in muscle contractions. The basal layer refers to a part of the endometrium that remains intact during menstruation, but it does not have a role in the contraction process either.