Organ
Myometrium
Interlacing uterine muscle for growth and contraction
High-yield
Postpartum myometrial contraction compresses vessels at the placental bed. Inadequate contraction is uterine atony, an important cause of hemorrhage.
Overview
Myometrium forms most of the uterine wall. Its smooth-muscle bundles interconnect in several directions around vessels and the uterine cavity. During pregnancy, cellular enlargement, growth and changes in electrical coupling prepare this network for coordinated labor contractions.
Reference facts
- Location
- Between the endometrial mucosa and outer uterine covering, forming the bulk of the body and fundus.
- Parts
- Interconnected smooth-muscle bundles with regional differences in orientation and vascularity; simple three-layer descriptions are only approximations.
- Blood supply
- Uterine arterial branches form arcuate vessels within the wall and radial branches toward the endometrium.
- Innervation
- Receives autonomic fibers through uterine plexuses; hormones, local mediators and myocyte electrical activity also govern contraction.
- Venous/Lymphatic drainage
- Venous channels join uterine plexuses; lymph communicates with pelvic and lumbar pathways.
- Relations
- Directly underlies endometrium and is covered by serosa where peritoneum covers the uterus, with connective tissue at nonperitoneal surfaces.
- Function
- Accommodates pregnancy, generates uterine contractions and contributes to hemostasis after placental separation.
Clinical correlation
Leiomyomas arise from uterine smooth muscle, while adenomyosis involves endometrial glands and stroma within myometrium. These conditions differ anatomically even when symptoms such as bleeding or pain overlap.
Frequently asked questions
Where is the myometrium located?
Between the endometrial mucosa and outer uterine covering, forming the bulk of the body and fundus.
What does the myometrium do?
Accommodates pregnancy, generates uterine contractions and contributes to hemostasis after placental separation.
What are the parts of the myometrium?
Interconnected smooth-muscle bundles with regional differences in orientation and vascularity; simple three-layer descriptions are only approximations.
What is the blood supply of the myometrium?
The myometrium is supplied by the uterine arterial branches form arcuate vessels within the wall and radial branches toward the endometrium.