It's the muscle layer of the uterine wall that helps the uterus contract during labor. The endometrium is made up of two layers. Right above the myometrium is the stratum basalis, or basal layer.

The thick center layer of the uterus is the myometrium, which is made of smooth muscle cells. The outer layer is called the perimetrium or serosa and is made of thin epithelial cells.

which are benign growths in the uterine muscle layer. To cause uterine enlargement, adenomyosis, a disorder in which the lining of the uterus develops into the muscle wall, is commonly linked with ...

Fibroids occur when a single muscle cell in the wall of the uterus multiplies ... subserous (located in the outer wall of the uterus); intramural (found in the muscular layers of the uterine wall); ...

Fibroids can grow on the inside or outside of the uterus or between the muscle layers that make up the walls. Most people who experience back pain have fibroids growing on the outside of their uterus.