SUPPORT OF PELVIC VISCERA
To clarify the relationships
of muscles and fasciae in supporting the pelvis, with particular reference to
the vagina and internal female genitalia, the uterus, in the accompanying
picture, has been elevated upward and backward.
The plane chosen for the section (small upper diagram) runs from a point
anterior to the body of the uterus down through the anterior vaginal fornix and
along the longitudinal axis of the vagina to the perineum. At this level, the
large iliac vessels run close to the superior pubic rami which form the lateral
pelvic walls. These pubic rami are connected to the ischiopubic rami across the
obturator foramen by the obturator membrane, the obturator internus muscle, and
the obturator fascia. The broad ligaments begin at the lateral pelvic walls as double
reflections of the parietal peritoneum, forming large wings, which divide to
include the uterus and separate the pelvic cavity into anterior and posterior
compartments. They are continuous with the peritoneum of the bladder anteriorly
and the rectosigmoid posteriorly. The broad ligaments contain fatty areolar
tissue, blood vessels, and nerves, and at their apices invest the round
ligaments, which are condensations of smooth muscle and fibrous tissue holding
the uterus forward and inserting below and anterior to the fallopian tubes. The
left ovary has been lifted up to demonstrate the uteroovarian and
infundibulopelvic ligaments, the latter containing the ovarian blood supply.
The bladder peritoneal reflection has been detached from the uterus, revealing the
endopelvic or uterovaginal fascia, which runs laterally to the pelvic wall as
the cardinal ligament, and with the associated blood vessels, nerves, and fat
forms the parametrium. The uterine arteries and veins extend medially from
their origins in the hypogastric vessels to the lateral vaginal fornices. The
ureters (cross-sectioned) at this point pass beneath the uterine vessels and
then continue in the uterovaginal fascia medially and anteriorly across the
upper vagina into the bladder. The close proximity of the ureters to the
uterine blood supply and vagina explains why they may easily be injured during
hysterectomy and in operations to repair lacerations of the endopelvic fascia.
