PELVIC VISCERA AND SUPPORT—FROM ABOVE
Although the muscular hammock of the levator plate provides the caudal (inferior) floor for the pelvic viscera, the organs of the pelvis have their own mechanisms of support. When either or both of these two support systems fail, this failure can result in clinical dysfunction. Understanding these supports can not only explain pathologies when present but also the therapeutic strategies that may be applied in their correction.
The term endopelvic fascia (actually a pseudofascia) refers to the
reflections of the superior fascia of the pelvic diaphragm upon the pelvic
viscera. At the points where these hollow organs pierce the pelvic floor,
tubular fibrous investments are carried upward from the superior fascia as
tightly fitting collars, which blend with and may even become inseparable from
their outer muscle coat. Thus, three tubes of fascia are present, encasing,
respectively, the urethra and bladder, the vagina, and the lower uterus and the
rectum. These fascial envelopes, with interwoven muscle fibers, are utilized in
the repair of cystoceles and rectoceles anteriorly and posteriorly. It is also
within this fibrous tube investing the lower uterine segment that the so-called
intrafascial hysterectomy is performed in an effort to protect the support of
the remaining vaginal cuff. The vesical, uterine, and rectal layers of
endopelvic fascia are continuous with the superior fascia of the pelvic diaphragm,
the obturator fascia, the iliac fascia, and the transversalis fascia.
Uterine support is maintained directly and indirectly by a number of
peritoneal, ligamentous, fibrous, and fibromuscular structures. Of these, the
most important are the cardinal ligaments and the pelvic diaphragm with its
endopelvic fascial extensions. The vesicouterine peritoneal reflection is
sometimes referred to as the anterior ligament of the uterus, and the
rectouterine peritoneal reflection as the posterior ligament. These are not true
ligaments and they provide only limited additional support. The round ligaments
are flattened bands of fibromuscular tissue invested with visceral peritoneum
that extend from the angles of the uterus downward, laterally, and forward,
through the inguinal canal to terminate in the labia majora.
The sacrouterine (uterosacral) ligaments are true ligaments of
musculofascial consistency that run from the upper part of the cervix to the
sides of the sacrum. At the uterine end, they merge with the adjacent posterior
aspect of the cardinal ligaments and the endopelvic fascial tube. The broad
ligaments consist of winglike double folds of peritoneum reflected from the
lateral walls of the uterus to the lateral pelvic walls. Their superior margins
encase the uterine tube and round ligaments. They then continue as the
infundibulopelvic ligaments as they progress laterally and superiorly.
Inferiorly, the ensheathed uterine vessels and cardinal ligaments may be felt.
Within the two peritoneal layers are to be found loose areolar tissue and fat, the fallopian tube, the round ligament, the ovarian ligament, the
parametrium, the epoöphoron, paroöphoron and Gartner duct, the uterine and
ovarian vessels, lymphatics, and nerves.
The cardinal or transverse cervical ligaments (of Mackenrodt) are
composed of condensed fibrous tissue and some smooth muscle fibers. They extend
from the lateral aspect of the uterine isthmus in tentlike fashion toward the
pelvic wall, to become inserted, fan-shaped, into the obturator and superior fasciae of the pelvic diaphragm. This
triangular septum of heavy fibrous tissue includes the thick connective tissue
sheath, which invests the uterine vessels. Mesially and inferiorly, the
cardinal ligaments merge with the uterovaginal and vesical endopelvic fascial
envelopes. Posteriorly, they are integrated with the uterosacral ligaments.
The vesical and rectal endopelvic fasciae maintain bladder and rectum support, respectively.
