This is part3 of Dr. Attef presentation about structural and functional components of continence mechanism in females
Part3: Female Pelvic floor component
A-Pelvic support
The obturator internus
muscle, similar to the bony pelvis, provides a framework for attachment of the
pelvic floor to the pelvic bone.
The obturator internus fascia, referred to as
the arcus tendineus or tendineus arc, is a tense fibrous band of fascia that
traverses the medial aspect of the muscle between pubic bone and ischial spine
bilaterally
There are
three supporting layers comprising the pelvic floor: the endopelvic fascia, the
pelvic diaphragm and the urogenital diaphragm
B- Levator ani
muscle
Although
variation in nomenclature has often confused structural pelvic anatomy, it is
usually agreed that levator ani muscle and levator fascia provides support of
bladder and urethra almost entirely
Levator ani
functions as a unit but is described in two main parts: the diaphragmatic part
(coccygeus and iliococcygeus muscles) and the pubovisceral part (pubococcygeus
and puborectalis).
Innervation is provided primarily through the anterior
sacral roots of S2, S3, and S4; additional innervation may be provided to pubovisceral
components through branches of pudendal nerve, although this is controversial
C- Pelvic
ligaments and fascia
Pelvic
ligaments serve mainly to keep structures in positions where they can be
supported by the muscular activity rather than as weight bearing structures
themselves.
The loss of normal muscular
support leads to sagging and widening of the urogenital hiatus and predisposes
patients to the development of POP.
Pelvic ligaments and endopelvic fascia
attach the uterus and vagina to the pelvic side walls so these structures can
be supported by the muscles of the pelvic floor.
The entire complex then rests
on the levator plate, where it can be closed by increases in intra abdominal
pressure by a "flap-valve" effect
Levator
fascia provides support to pelvic structures across its entire surface.
However, 4 specialized fascial condensations provide principal support for the
anterior vaginal wall, specially the pubourethral, urethropelvic, vesicopelvic
and cardinal ligaments
a- Pubourethral ligaments are bilateral
structures; they originate on the pubic bone and the arcus tendineus fascia
pelvis on the point where the arcus joins the anterior levator arch. They
attach superiorly and laterally along the urethra
The
pubourethral ligament is the female analogue of
the puboprostatic ligament. Functionally, the pubourethral ligaments protect
against rotational descent of the mid urethra during increases in intra abdominal
pressure and provide passive support to maintain the urethra in a normal retro
pubic position
b- Urethropelvic ligaments describe all structures that provide lateral support
of the urethra to the pelvic wall. Urethropelvic ligaments may undergo avulsion
and stretch consequent to vaginal delivery and aging, resulting in
deterioration of the lateral support for the proximal urethra
c- Vesicopelvic ligaments are levator fascia, originating at the tendineus arc
of the obturator and, after splitting upon the approach to the bladder, it is
renamed perivesical fascia on its vaginal and endopelvic fascia on its
abdominal surface
d- Cardinal ligaments
Anatomically, the cardinal ligaments are posterior
extensions of the vesicopelvic ligaments. Because of the proximity of the
bladder base to the cervix, deterioration of cardinal ligaments may in tandem
jeopardize support of the bladder base and cervix, leading to cystocele and
uterine descents. At hysterectomy failure to re-approximate the cardinal
ligaments properly during culdoplasty may facilitate future development of the
central cystocele defect
Uterosacral
ligaments are a more medial segment of the endopelvic fascia, at the level of
the cervix and upper vagina, and serve to stabilize the visceral structures
posteriorly toward the sacrum
Rectovaginal fascia
(Denonvillier’s fascia) was noted to attach to the pelvic sidewall. This
attachment amounts to a fusion of the rectovaginal fascia with the aponeurosis
of the levator ani muscle. It occurs along a well-defined line that begins at
the perineal body. This line of attachment converges to the arcus tendineus
fasciae pelvis at a point approximately midway between the pubic symphysis and
the ischial spine to form a Y configuration on the sidewall of the pelvis
The rectovaginal fascia supports the posterior compartment analogous to the
pubocervical fascia in the anterior compartment
D- Connective
tissues
It is composed primarily of
elastin and collagen fibers in a polysaccharide ground substance. Connective
tissue is not static; instead, it is a dynamic tissue which undergoes constant
turnover and remodeling in response to stress. Hormonal changes seem to have
significant effects on collagen, and these effects are probably of great
importance during pregnancy and parturition, as well as in aging
E-Perineal body
The body is a
pyramid-shaped structure made up of smooth muscle, skeletal muscle, fibrous and
elastic tissue, as well as nerve fibers and ganglia. The large amount of the
smooth muscle and elastic fibers distends, allowing significant distortion
followed by elastic distensibility is lost, which may occur with surgical or
obstetrical trauma, the vaginal outlet can become physiologically unstable.
It
is generally accepted that weakness in this area is a precursor to, or
reflection of, significant problems at one or more levels of pelvic support.
The perineal
body represents the point at dorsal attachment of the three muscles of the
perineum: the bulbocavernosus, ischiocavernosus and superficial transverse
perinei.
Also attaching at the perineal body are slips of the puborectalis and
pubococcygeus muscles from the pelvic floor as well as fibers from the external
anal sphincter. Superficially, the perineal body is associated with Colles’
fascia
F- Urogenital Diaphragm
The muscles of the urogenital diaphragm reinforce the
pelvic diaphragm anteriorly and are intimately related to the vagina and the
urethra.
They are enclosed between the inferior (perineal membrane) and
superior fascia of the urogenital diaphragm.
The muscles include the deep
transverse perineal muscle and sphincter urethrae
