Anatomy of the uterus

In this note, we will consider the anatomy of the uterus (uterus)

It is an organ of the female reproductive system.

The uterus takes part in the implantation of a fertilized oocyte, provides fetal develpment and parturition, and is also a direct anatomical substrate of menstrual function.

Holotopy

It is projected onto the pubic region of the anterior abdominal wall.

It is located in the pelvic cavity in a certain position:

the term anteversio uteri means the inclination of the uterus anteriorly in relation to the axis pelvis plane;
the term anteflexio uteri means the inclination of the fundus and body of the uterus anteriorly in relation to the isthmus and cervix.

Skeletotopy

It is located between the 2nd and 4th sacral vertebrae (S 2-S4).

Syntopy

The urinary bladder is located anteriorly to it.

The rectum lies posteriorly.

The uterine appendages (ovary and its rudimentary formations, uterine tube) are located laterally.

Uterine tube<br />
(tuba uterina) — Uterine tube
(tuba uterina)

The loops of the small intestine lie superiorly.

The vagina is located inferiorly.

Macroscopic structure

The uterus consists of the following parts:

1. The fundus of the uterus (fundus uteri), which is the superior convex part of the uterus located above the confluence of the fallopian tubes.

2. The body of the uterus (corpus uteri), which is the main part of the organ.

3. The isthmus of the uterus (isthmus uteri), which is a narrowed part

Isthmus of the uterus<br />
(corpus uteri) — Isthmus of the uterus
(corpus uteri)

4. The cervix of the uterus (cervix uteri), which has two parts:

the vaginal part of the cervix (portio vaginalis cervicis), which extends into the vagina;

the supravaginal part of the cervix (portio supravaginalis cervicis), which is located superiorly to the vagina.

Supravaginal part of the cervix (portio supravaginalis cervicis)

5. The vaginal part shows the external os of the uterus (ostium uteri), which leads into the cervical canal and its cavity.

The external os of the uterus has the shape of a transverse fissure, and it is delimited by the anterior labium (labium anterior) and the posterior labium (labium posterior)

The uterus has the following surfaces:

The vesical surface (facies vesicalis), which is facing the bladder.

The intestinal surface (facies intestinalis), which is facing the rectum.

Intestinal surface (facies intestinalis)

And also, two borders:

The right border of the uterus (margo uteri dexter)
The left border of the uterus (margo uteri sinister)

Left border of the uterus (margo uteri sinister)

The wall of the uterus consists of several layers.

The mucous membrane (tunica mucosa), which is called the endometrium (endometrium) in the uterus and is lined with a simple columnar epithelium, which in the vaginal part is replaced by a striated squamous epithelium

Inside the uterus, there is the uterine cavity (cavitas uteri)

which passes into the cervical canal (canalis cervicalis uteri)

The mucous membrane of the uterus has no folds, except for the cervical canal, where the palmate folds (plicae palmatae) are located

In addition, the uterine mucosa contains uterine glands (glandulae uterinae), which open on the surface of the epithelium.

The muscular layer (tunica muscularis), which is called the myometrium (myometrium) in the uterus and is the thickest layer of its wall.

It has three layers:

Longitudinal layer (stratum longitudinale), which is an external thin layer.
Circular layer (stratum circulare), which is the most pronounced.
Longitudinal layer (stratum longitudinale), which is an internal thin layer.

The serosa (tunica serosa), which is called the perimetrium in the uterus and is a visceral sheath of the peritoneum.

In relation to the peritoneum, the uterus is located mesoperitoneally. The lateral surfaces of the isthmus and the supravaginal part of the cervix, as well as the vaginal part of the cervix are not covered with the peritoneum.

Between the rectum and the uterus, there is the recto-uterine pouch (excavatio rectouterina), which is also known as the pouch of Douglas;

Between the bladder and the uterus, there is a vesico-uterine pouch (excavatio vesicouterina)

In addition, in the anatomy of the uterus, there is such a structure as the parametrium (parametrium)

It is the loose tissue around the uterus that is more pronounced anteriorly and laterally to the isthmus of the uterus. The parametrium gradually passes down into the paracervical tissue fiber and the tissue surrounding the vagina. Anteriorly, it passes into the paravesical tissue, and posteriorly it passes into the pararectal tissue.

Ligaments of the uterus

The uterus has 3 ligaments:

The broad ligament of the uterus (lig. latum uteri), which acts as the mesentery. Vessels and nerves pass between its sheaths, surrounded by connective tissue.

The ligament has the shape of an irregular quadrilateral located in the frontal plane.

There is a number of structures within its thickness:

the uterine tube (tuba uterina)

the proper ligament of the ovary (lig. ovarii proprium)

Ligament of the ovary (lig. ovarii proprium)

the round ligament of the uterus (lig. teres uteri)

Round ligament of the uterus (lig. teres uteri)

the mesentery of the uterine tube (mesosalpinx)

Mesentery of the uterine tube (mesosalpinx)

the ovary (ovarium) is attached to the posterior sheath

The round ligament of the uterus (lig. teres uteri), which arises from the lateral border of the uterus.

It is located within the broad ligament of the uterus, passes through the inguinal canal, and breaks up into fibrous bundles that end in the thickness of the labia majora.

Cardinal ligaments of the uterus (ligg. cardinalia uteri), which are strands of fibrous and smooth muscle fibers stretched between the isthmus of the uterus and the lateral wall of the pelvis.

Supporting structures of the uterus

The uterus remains in its position due to a number of anatomical structures and physical factors.

Features of the structure of the serosa of the uterus, which contains a large number of elastic fibers and is tightly fused with the myometrium
Ligaments of the uterus
Ligaments of the ovary
The connection of the uterus with the vagina and tissues of the perineum
Recto-uterine ligaments and muscles that attach the uterus to the rectum
Fibrous tissue that fuses the cervix of the uterus with the urinary bladder
Intra-abdominal pressure

Blood supply

The uterine artery (a. uterina)

Venous drainage

Uterine veins (vv. uterinae) drain blood into the uterine venous plexus.

Lymph drainage

Lumbar lymph nodes (nodi lymphatici lumbales)
The internal iliac lymph nodes (nodi lymphatici iliaci interni)
The sacral lymph nodes (nodi lymphatici sacrales)
The deep inguinal lymph nodes (nodi lymphatici inguinales profundi)
The superficial inguinal lymph nodes (nodi lymphatici inguinales superficiales)

Innervation

Afferent innervation is provided by the sensitive fibers of the sacral spinal nerves.
Parasympathetic innervation is provided by fibers of the pelvic splanchnic nerve from the sacral parasympathetic nucleus.
Sympathetic innervation is provided by the sympathetic plexus.

Dictionary