**1. Introduction**

### **1.1 The uterus**

The uterus is an organ with a particular anatomic situation localized with the uterine body intraperitoneally, the isthmus extra-peritoneally, and the cervix can be considered visible intravaginal organs. The uterine body is coated by the visceral peritoneum, which intimately adheres to its sides. In front, the visceral peritoneum reflects it on the bladder and in the back to the rectum. On the lateral side, the visceral uterine peritoneum detaches from the two sides of the uterus into two sheets that are joined to each other but are anatomically distinct and surgically separable, forming *broad ligaments*.

The uterus is maintained in anatomical position inside the pelvis by two systems: a *suspension and orientation system* for its intra-abdominal part and by a *supporting system* for the retroperitoneally part of the isthmus, cervix, and upper vagina. (Yabuky).

### **2. The suspension and orientation system of the uterus**

The suspension and orientation system of the uterus consists of *broad ligaments, round ligaments*, *infundibulopelvic ligaments,* and the *parietal peritoneum*.

*Round ligaments* play a minor supporting role, the main one being the orientation of the uterus. Round ligaments are active elements that contain an essential contingent of smooth muscle fibers. The anatomic origin is located cranially at the level of the uterine fundus, under the insertion of uterine tubes. Each round ligament engages through the homologous inguinal canal, to be inserted into the thickness of the labia majora.

*Broad ligaments* result in the lateral reflection of the pelvic parietal peritoneum on each side to the two sides of the uterus. After the peritoneal sheets detach from the pelvic walls, they re-join and form two peritoneal folds cranially suspended by the round ligaments. Frontally, broad ligaments are trapezoidal, with a caudally located base. The orientation of the plan containing the broad ligaments depends on the position of the uterus (ante- or retroversion).

The *pelvic parietal peritoneum* is an essential support for the uterine body, which becomes visible, particularly in vaginal hysterectomy. Access to the superior connective-vascular pedicle (round ligament, utero-ovarian ligament, and superior uterine pedicle) is profoundly difficult if the peritoneum of the broad ligaments is not sectioned as far as possible so that it loses contact with the pelvic parietal and visceral peritoneum. The tensile strength of the peritoneum and the perforation strength of broad ligaments are outstanding. Even if the uterus is disconnected from its primary support, it is held in the pelvis by the peritoneal connections.

*Infundibulopelvic ligaments* indirectly suspend the uterus via the ovary and utero-ovarian ligaments. Infundibulo pelvic ligaments have a mesenteric structure with a vascular and nerve fiber content that generally does not exert a suspension tension on the uterus. In pathological situations that cause their shortening and retraction generates resistance to the tendency to caudal traction of the uterus.

#### **3. The supporting system of the uterus**

The supporting system reunites all the elements that work together to maintain the uterus in its intrapelvic anatomical position and resist the descending tendency generated by the weight of the intestines at rest or under effort.

Biomechanical studies show that the support of the uterus and the upper part of the vagina are provided by the *four-wire system*, where the *cardinal ligaments* anchor the pericervical ring vertically and *uterosacral ligaments* dorsally.

The supporting system anchors the uterus and vagina to the pelvic brim: the *pubocervical ligaments* anteriorly and the *transverse cervical ligament (cardinal ligaments)* cranially and *uterosacral ligament* posteriorly. All these ligaments converge to the pericervical ring. The pericervical ring of the uterus is the insertion area for the supporting structures, and it forms a virtual delimitation between the intraperitoneal and extraperitoneal parts of the uterus. Pericervical ring also offers support for a vaginal vault.

*Transverse cervical ligaments (cardinal ligaments)* are oriented vertically. They are formed by two segments: a fibroconnective structure that joins the uterosacral ligaments close to the pericervical ring and a mesenteric structure containing blood, lymphatic vessels, and nerves as a distal segment. In the cardinal ligament, the deep uterine vein delimits a cranial segment containing vessels and a caudal one containing nerves (**Figure 1**).

Cardinal ligaments provide reliable support for the vascular and lymphatic axes that converge or emerge in the uterus. Their fibers dissipate in the

*Perspective Chapter: Total Vaginal Hysterectomy for Unprolapsed Uterus DOI: http://dx.doi.org/10.5772/intechopen.101383*

#### **Figure 1.**

*The cardinal ligament consists of three segments: Proximal and intermediate segments containing the mesenteric elements and the terminal ureter and a common segment with the homologous uterosacral ligament, which is the main support element of the pericervical ring.*

pubocervicovesical fascia towards the cervix uteri and superior vagina at the level of the cervical ring, and the fascial and areolar structures towards the pelvic walls, structures that cover the pelvic diaphragm, the obturator pelvic fascia, and the tendinous arch of the pelvis (arcus taendineus fascia pelvis-ATFP). (Campbell).

*The sacrouterine ligaments* have their origin in the posterior part of the pericervical ring and the posterior-lateral portion of the vaginal fornices, structures that continue the cardinal ligaments. Posteriorly, the uterosacral ligaments insert into the presacral fascia at the level of the sacroiliac joints S2-S4. Utero-sacral ligaments run in the supra levator part of the vagina, forming with the infra levator segment at an angle of 130°. (Chen) (**Figure 2**).

Like the cardinal ligaments, the uterosacral ligaments defined three segments: a proximal segment that merges with the cardinal ligament, an intermediate segment that represents the structure that can be used as a suspension element, and a distal segment that merges with the presacral fascia. Sacrouterine ligaments contain nervous

#### **Figure 2.**

Orienting-supporting *system of the uterus* supporting system*: 1 = pericervical ring. Spatial orientation of the cardinal (blue arrow) and uterosacral ligaments (red arrow): 4 = uterine artery 5 = ovary, 6 = fallopian tube, 2 = pubocervical fascia, 3 = rectovaginal septum.* Orienting system *(green arrow): 8 = round ligament, 7 = infundibulo-pelvic ligament.*

**Figure 3.**

*Definition of three segments of uterosacral ligaments. MRI reconstruction -spatial disposition of posteriorly oriented uterosacral ligaments (in green) and cardinal ligaments oriented vertically (in beige yellow), P = pubis arch, Isch = ischion, Il = ilion, S = sacrum.*

fibers from the superior hypogastric plexus. Those innervating the urinary bladder are of particular importance in nerve-sparing surgery for cervical cancer (**Figure 3**).
