Three layers of the wall of the uterus
Author: Achudhan Karunaharamoorthy • Reviewer: Dimitrios Mytilinaios MD, PhD The uterus, also known as the womb, is an about 8 cm long hollow muscular organ in the female pelvis and lies dorsocranially on the bladder. It consists of several anatomical parts, such as the cervix, isthmus, and body. While its anatomy sounds simple, its histology is more complicated. It consists of three major layers, but the exact histological structure depends upon the state - if it is in the or proliferative phase. Also, as an organ of the female reproductive system it is responsible for the development of the embryo and fetus during pregnancy. This article will describe the anatomy, histology, and functions of the uterus, as well as shed some light on the basics of the menstrual cycle. Key facts about the uterus
EmbryologyThe uterus develops from the paranemesophrenic (Müllerian) ducts, which are the primordial fetal structures of the female reprodutive tract. More specifically, the uterovaginal primordium is formed by the fusion of the caudal, vertical parts of the paranemesophrenic ducts. This primordium will give rise to the lower part of the uterus that will slowly enlarge during development, ultimately resulting in the fundus and body of the uterus in the adult female. One can begin to see clear signs of the uterine body at a gestational age of 9 weeks. The endometrium and the muscular wall of the uterus develop from the mesenchyne of the genital cord. Anatomy of the uterusParts and positionThe uterus is divided into the cervix, isthmus and corpus. The cervix (neck) lies subperitoneally and consists of a part projecting into the vagina (vaginal portion or portio) and a part fixed in the parametrium (supravaginal portion). The cervical canal has two orifices: the internal orifice to the isthmus and the external orifice to the vagina. The isthmus is an about 1 cm long narrow passage connecting the cervix and corpus. The corpus (body) lies intraperitoneally and has a “triangle” lumen through its connection to the isthmus and both fallopian tubes. The base of the uterus is called fundus. In most women the corpus is bent forward against the cervix at the isthmus (anteflexion) and the long axis of the uterus is inclined towards the vagina (anteversion). The shape and size however may vary depending on age, number of pregnancies and hormonal status. Need help learning and memorising the anatomy of the uterus? Find out why our anatomy quiz questions are the secret to your success. The uterus is surrounded by the circumjacent connective tissue (parametrium). The peritoneum covers the uterus almost completely (except the ventral part of the cervix) forming two recesses: ventrally the vesicouterine pouch and dorsally the rectouterine pouch (pouch of Douglas). If you already feel like a pro on the female reproductive organs, take the following quiz on the uterus, uterine tubes and ovaries to prove it! NeurovasculatureIt is supplied by branches of the uterine arteries (branch of the internal iliac artery). One branch travels within the broad ligament of the uterus until the region close to the ovarian hilum, where it forms an anastomosis with the uterine branches of the ovarian artery (branch of the abdominal aorta). The second branch supplies the cervix and anastomoses with several branches of the vaginal artery. The uterine artery also gives several perforating branches within the uterine wall that form two surrounding systems around the uterus called the posterior and anterior arcuate arteries. The venous blood drains through the uterine venous plexus into the internal iliac vein. The nerves derive from the inferior hypogastric plexus. Sympathetic innervation originates from the T12 and L1 spinal segments, while the parasympathetic nervous supply is provided by the S2 to S4 spinal segments. All vessels and nerves run through the lateral ligaments (ligamentumlatum uteri), a broad duplication of the peritoneum connecting the lateral wall of the uterus with the pelvic wall. LymphaticsLymphatic vessels drain lymph from the body and cervix of the uterus to the iliac lymph nodes (external and internal), as well as the obturator lymph nodes. In turn, the fundus is drained to the para-aortic lymph nodes. For more information about the uterus, take a look below: Histology of the uterusThe uterus has three layers: mucosa (endometrium), muscularis (myometrium) and serosa/adventitia (perimetrium).
Do you want to find out how much you've learned about the histology of the uterus? Take a sneak peek below! FunctionThe uterus plays an important role in human reproduction. It is the organ where the implantation and nourishment of the fertilized ovum takes place. Furthermore it helps pushing out the baby during birth through muscle contraction. The uteruses of women in childbearing age underlie an about 28-day hormone-controlled rhythm (menstrual cycle) which goes through three phases:
Summary
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