Myometrium
The myometrium is a thick muscular layer that is continuous with the muscular layer of the uterus and vagina. It is the thickest layer of the uterine wall. The myometrium is composed of three layers of smooth muscle: the inner, middle and outer layers.
The inner and outer layers have smooth muscle bundles that lie longitudinally and parallel or to the long axis of the uterus.
The middle layer is comprised of large blood vessels and lymphatics and is also known as the stratum vasculare. There are also muscle fibers arranged in a concentric or spiral pattern in this layer.
All three layers of the myometrium work together during uterine contraction to expel the contents of the uterine lumen. In the non-pregnant uterus, the smooth muscle cells measure approximately 50 micrometers in length. However, during pregnancy, the uterus experiences significant enlargement. This growth is mainly due to the hypertrophy of existing smooth muscle cells, which can reach lengths of over 500 micrometers.
Terminology: | English and latin: myometrium |
Location: | Thickest layer of the uterine wall |
Function: | Composed of smooth muscle, therefore works with other layers of the uterine wall for uterine contraction. |
Learn more about the uterus and the other uterine walls in this study unit:
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