**1. Introduction**

Approximately one-third of adult women affected with pelvic organ prolapse, have significant impact on their quality of life and emotional well-being. Epidemiologic survey of the United States showed that pelvic organs prolapse (POP) becomes more prevalent as the population age advances [1]. Women have 11.1% lifetime risk of undergoing surgery for prolapse by age 80 [2] and a 30% risk of reoperation over a period of 4 years [3].

Pelvic organ prolapse is defined as the descent of the anterior, posterior, and/or apical vaginal compartment(s) with protrusion of one or more pelvic organs (e.g. bladder, uterus,

post-hysterectomy vaginal cuff, small bowel, or rectum) into the vagina [4]. These pathological changes are due to loss of structural support to pelvic organs resulting in an impact on women's quality of life. They arise because of injury and deterioration of the muscles, nerves, and connective tissue that support the pelvic floor and its contents.

**2.2. Muscular support**

attach to the lateral walls of the vagina.

between the rectum and anus.

*2.2.2. Coccygeus muscle*

**2.3. Facial support**

*2.3.1. The ATLA*

Levator ani muscles form the pelvic diaphragm, which provide the firm tissue support of the pelvic floor. These muscles are attached to the inner surface of the true pelvis form the muscular floor of the pelvis. Three components of the levator ani muscles recognized are pubococcygeus, iliococcygeus and puborectalis [5]. The **pubococcygeus**, also known as pubovisceralis muscle, arises from the anterior portion of the arcus tendineus and the back of the body of the pubis and is inserted with other parts of levator ani as anococcygeal raphe which forms a hiatus or levator plate. Pubovisceralis is further divided into pubovaginalis, puboanalis, and puboperinealis muscles [6]. The fibers attached to the perineal body are puboperinealis and draw this structure toward the pubic symphysis. The fibers attached to the anus at the intersphincteric groove between the internal and external anal sphincter are puboanalis. It elevates the anus and along with the rest of the pubococcygeus and puborectalis fibers keep the urogenital hiatus closed. Pubovaginalis refers to the medial fibers of pubococcygeus that

Pathophysiology of Pelvic Organ Prolapse http://dx.doi.org/10.5772/intechopen.76629 7

The iliococcygeus arises from the arcus tendineus of the levator ani to the ischial spine and inserted into anococcygeal raphe. The puborectalis fibers of the levator ani (LA) muscle arises on lowest portion of pubic symphysis. It passes downward and backward on either side of vagina and fuses behind the rectum and form U-shaped muscular sling encircling the junction

It forms the most posterior division of levator ani, arises from ischial spine and inserted into coccyx and lower sacrum. The piriformis and obturator internus form the posterolateral pelvic walls. The piriformis arises from the anterior and lateral surface of the sacrum and leaves the pelvis through the greater sciatic foramen, inserted to the greater trochanter of the femur. The obturator internus muscle arises from the ilium and ischium pelvic surfaces. It leaves the pelvis through the lesser sciatic foramen and inserted to the greater trochanter of the femur.

Endopelvic is composed of loose arrangements of collagen, elastin, and adipose tissue and

Arcus tendineous levator ani, dense connective tissue structure courses along the medial surface of the obturator internus muscle, serves as the point of origin for parts of the levator ani muscles (iliococcygeus). ATLA extends anteriorly from pubic tubercle to ischial spines posteriorly. The arcus tendineous fascia pelvis (ATFP), a thickening of fascia covering the medial

The piriformis and obturator internus function as an external hip rotator.

condenses to form cardinal and uterosacral ligaments.

*2.2.1. Levator ani*

Despite the high prevalence of POP, current treatment options remain suboptimal and do not address the underlying mechanisms of disease. Therefore, without improving our understanding of the pathophysiology of POP, treatment options and prevention of recurrence of POP would be limited. It is important to understand the pelvic floor support and the risk factors leading to POP. This chapter would include a review of pelvic floor support and the pathophysiology of POP.
