Comprises a thick layer of smooth muscle continuous with the vagina
Interweaving smooth muscle bundles contract during orgasm and to expel uterine contents during menstruation and parturition.
Branches of the uterine artery course through the myometrium and form straight arteries, which reach only the stratum basalis, and spiral arteries, which travel to the stratum functionalis.
Endometrium
The inner most layer; it faces the uterine cavity
Can be subdivided into the stratum basalis, which lies against the myometrium, and the stratum functionalis, which faces the uterine cavity (be aware that some authors further divide the stratum functionalis into the stratum compactum and spongiosum).
Tubular glands of the endometrium are surrounded by stroma, in which we can also see blood vessels.
The endometrial glands comprise columnar ciliated and secretory cells,
The stratum functionalis, but not the stratum basalis, cyclically proliferates and sheds over the course of a menstrual cycle.