The female pelvic floor consists of multiple layers of muscles and fascia that close off the pelvic outlet, through which the urethra, vagina, and rectum pass. These pelvic floor tissues support pelvic organs such as the uterus, bladder, and rectum, maintaining their normal positions.
Modern anatomical descriptions of the pelvic floor have become increasingly detailed, with the "compartment theory" as a representative concept. The core idea of this theory involves dividing the pelvic floor into three compartments in the vertical direction: the anterior compartment, which includes the anterior vaginal wall, bladder, and urethra; the middle compartment, which includes the vaginal apex and uterus; and the posterior compartment, which includes the posterior vaginal wall and rectum. This allows prolapse to be quantified within each compartment.
In the horizontal direction, the theory of three levels of pelvic floor support was proposed by DeLancey in 1994. According to this theory:
- Level 1 is the upper layer of support structures (the uterosacral-cardinal ligament complex).
- Level 2 is the lateral support structures (the levator ani muscle group and the connective tissues of the bladder and rectal-vaginal fascia).
- Level 3 is the distal layer of support structures (the perineal body and the sphincter complex).
The compartment theory of the pelvic floor forms the anatomical foundation for the surgical treatment of pelvic floor dysfunction-related disorders.
Figure 1 DeLancey's three-level theory of pelvic floor support structures
PS: Pubic symphysis
PUL: Pubourethral ligament
PCM: Pubococcygeus muscle
ATFP: Arcus tendineus fascia pelvis
PB: Perineal body
PCF: Pubocervical fascia
EAS: External anal sphincter
PRM: Puborectalis muscle
RVF: Rectovaginal fascia
LMA: Longitudinal muscle of the anus
LP: Levator plate
USL: Uterosacral ligament
S: Sacrum