The uterine wall is the thick, muscular layer that forms the outer structure of the uterus. It consists of three main layers: the perimetrium, which is the outermost layer; the myometrium, which is the middle layer made of smooth muscle; and the endometrium, the innermost layer that thickens and sheds during the menstrual cycle. The primary function of the uterine wall is to support the fertilized egg during pregnancy. The myometrium contracts during labor to help push the baby out, while the endometrium provides a nourishing environment for the developing embryo.