female pelvic anatomy and the female urinary continence mechnisms

1.  The Extrinsic Continence Mechanism
PELVIC SUPPORTING STRUCTURES
 A. Bone
 B. Ligament
 C. Musculature
 The Intrinsic Continence Mechanism.

2.  The anatomic components necessary to meet this goal
are a well-vascularized urethral mucosa and
submucosa, a well-organized and functioning intrinsic
urethral smooth muscle, a properly functioning
striated sphincter with intact pudendal innervation
(i.e., rhabdosphincter), and a stable, supportive
hammock of surrounding muscular and fascial tissues

3. Analogy demonstrating the support
provided by the A, pelvic floor (water) and
ligaments (ropes) to the pelvic organs (ship).
B, Consequences of a pelvic floor muscle
weakness with increasing strain placed on
ligamentous structures. C, Ligamentous
damage as a consequence of loss of pelvic
floor muscle weakness.

4. A. Bone pelvis
 Bony structures act as anchors for the important
muscular and fascia.
 The pubic rami, ischial spines, and sacrum are the
anchoring points of the true bony pelvis,
 The pelvic floor is diamond-shaped with the pubic
symphysis and sacrum at the anterior and posterior
apices while the ischial spines serve as lateral anchors

6. B. Ligament
 The sacrospinous ligaments : from the ischial spines to the
anterolateral aspect of the sacrum and coccyx.
 the tendinous arc, condensation of pelvic fascia from the obturator
internus muscle, runs between the ischial spines and the lower
portion of the pubic symphysis.
 flanks the urethra and bladder neck anteriorly and rectum posteriorly
 provides lateral attachment of the pelvic diaphragm and its ligaments
.
 The perineal body is a tendinous structure located in the midline of
the perineum between the anus and the vaginal introitus, which
provides a central point of fixation for the transverse perineal
musculature.

7. C. Musculature
 The pelvic diaphragm
is composed of the
levator ani and
coccygeus muscles.
 The levator ani
muscle group and its
fascia is composed of
the pubococcygeus,
ischiococcygeus, and
iliococcygeus.

8.  The anterior part (pubococcygeus (puborectalis)) with its
overlying endopelvic fascia, directly attaches to the
bladder, urethra, vagina, uterus, and rectum
 The posterior part the posterior portion of the levator ani
and the coccygeus muscle. Arising from more posterior
portions of the tendinous arc and the ischial spines.
 The two sides fuse in the midline posterior to the rectum
and attach to the coccyx(allows maintenance of the normal
vaginal and uterine axis).

9.  The upper vagina and uterine cervix lie on this
horizontal plane created by the levator plate.
 The bladder, proximal vagina, and rectum rest on the
levator floor and become coapted against it during
periods of increased intra-abdominal pressure.
 This posterior muscle group is active at rest and
contracts during rectus abdominis contraction,
maintaining proper vaginal axis.

10.  Resting tone of the levator muscle, as well as reflex
and voluntary contraction, acts to pull the vagina and
rectum forward, thereby preventing incontinence of
both urine and stool.

12. Schematic diagram of the striated musculature of the pelvic floor. PR,
puborectalis; PC, pubococcygeus; IC, iliococcygeus; O, obturator muscle; TA,
tendinous arc of the obturator muscle.

13. d. Pelvic fascia
 Anterior vaginal wall support
 endopelvic fascia continuation of the abdominal
transversalis fascia
 The two fascial layers split at the levator hiatus to cover
the pelvic organs that traverse it.
 The superior or intra-abdominal segment
(endopelvic fascia) and the inferior or vaginal side of
the levator fascia together constitute the
pubocervical fascia.

14.  The specialization of levator fascia around the urethra, the
pubourethral ligament, represents a fusion of the
periurethral fascia and endopelvic fascia attaching to the
tendinous arc.
 The levator fascia associated with the bladder, the
vesicopelvic ligament or fascia, represents the fusion of
perivesical and endopelvic fascia attached to the tendinous
arc.
 This create ligamentous” structures that support the pelvic
viscera, such as the pubourethral ligaments, urethropelvic
ligaments, pubocervical fascia, and cardinal and uterosacral
ligaments.

18. Pubourethral Ligaments
 Condensation of levator fascia connecting the inner surface of the
inferior pubis to the midportion of the urethra.
 support the urethra and its associated anterior vaginal wall.
 These ligaments divide the urethra into proximal and distal halves; the
proximal or intra-abdominal portion is responsible for passive or
involuntary continence.
 The striated external urethral sphincter is located just distal to the
pubourethral ligaments so that the midurethra becomes primarily
responsible for active or voluntary continence. The distal one-third of
urethra is simply a conduit and does not significantly change
continence when damaged or resected.

19. Urethropelvic Ligaments
 The urethropelvic ligaments are composed of a two-layer condensation
of levator fascia, which provides the most important anatomic support
of the bladder neck and proximal urethra to the lateral pelvic wall

20. Schematic diagram demonstrating the urethropelvic ligaments, a
two-layer condensation of levator fascia which envelops the urethra
and surrounding neurovascular structures and attaches to the
lateral side wall.

21. Schematic diagram of the vesicopelvic ligament, the fascial condensation
providing lateral support to the bladder base and anterior vaginal wall

22. UTERINE AND VAGINAL VAULT SUPPORT
 cardinal ligaments.
 They support for the bladder base and can be seen
extending to the perivesical fascia.
 The broad ligaments provide additional uterine
support and are located more superiorly,

23. Posterior vaginal wall support
 Rectovaginal Septum
 Is a fascial extension of the peritoneal cul-de-sac between the vaginal
apex and the anterior rectal wall. This septum comprises two distinct
layers, the posterior vaginal fascia and the prerectal fascia, which
fuse distally at their insertion into the perineal body.
 More proximally, these fascial layers fuse with the cardinal-
uterosacral complex to provide support for the posterior vaginal
apex.
 The proximal posterior vagina and intrapelvic rectum are supported by
the pubococcygeus portion of the levator ani group, which inserts into
the midline raphe between the vagina and rectum.

26. The Intrinsic Continence Mechanism
 The female urethra is 4 cm long, with a diameter of 6
mm.
 The intrinsic urethral closure continence mechanism
relies on
1. Mucosal sealing effect of the urethra
2. Competent bladder neck
3. Functional urethral sphincter

27. The urethral mucosa
 is surrounded by a rich, spongy, estrogen-dependent
submucosal vascular plexus that is encased in fibroelastic
and muscular tissue.
 Estrogens enhance proliferation and maturation of the
urethral epithelium and increase vascular pulsations in the
urethral wall .
Bladder neck and proximal urethra is essential to maintain
continence,the orientation of the smooth-muscle fibers at
the bladder neck acts on contraction to open, rather than
close the bladder neck.

28. Functional urethral sphincter
Striated urogenital sphincter
 Has two distinct portions: an upper sphincteric portion,
which is arranged circularly around the urethra
corresponds to the rhabdosphincter; and a lower portion
comprising an arch-like pair of muscular bands.
 The striated sphincter muscle that is present along 80% of
the total anatomical urethral length.
 The sphincter has its largest diameter in the middle part of
the urethra

29. Architectural organization of the striated urethral sphincter. Location of its three
components: the urethral rhabdosphincter, the compressor urethra, and the
urethrovaginal
sphincter.

30. The Urethral Rhabdosphincter
 The fibers of the urethral rhabdosphincter surround
the urethral lumen from approximately 20 to 60% of
its length.
 the posterior portion between the urethra and the
vagina is relatively thin.
 Fibers in the posterior plane do not constitute a
complete ring, and the gap between the two ends of
the rhabdosphincter is bridged by the trigonal plate
which completes the ring
Functional urethral sphincter

31.  The rhabdosphincter fibers are not inserted in the
osteocartilaginous element of the skeleton; therefore, the
rhabdosphincter is a nonskeletal striated muscle in which
the fibers are inserted directly in the connective tissue of
the urethral wall.
 The orientation of the fibers both transversally and
longitudinally suggests that the
 rhabdosphincter works by nipping the dorsal and ventral
walls of the urethra toward each other while
simultaneously sliding them one from the other.

Functional urethral sphincter

32. 2. The Distal Urethral Sphincter
 is at the level of the distal third of the urethra , lying
approximately along 60–80% of its length.
 These striated fibers are not circular in orientation,
but consist of two bands that cover the ventral surface
of the urethra.
 Compressor urethra, originates in the perineal
membrane. e
 Urethrovaginal sphincter muscle, originates in the
vaginal wall.
Functional urethral sphincter

34. FUNCTIONAL ANATOMY
Urinary Continence at Rest
 Continence at rest depends on bladder neck closure,
urethral sphincter muscle tonic activity, and the urethral
mucosa.
 The fibers within the urethral sphincter are primarily slow-
twitch fibers capable of maintaining constant tonic activity.
 The urethral closure pressure measured during static
urethral profilometry may represent this permanent
intraurethral tone along with the mucosal seal effect.
 The levator ani muscles also have a constant tone that
helps support pelvic structures, including the urethra, by
the pubovaginalis portion.

35. Voluntary Continence During Storage
 When the bladder is full and when the patient has to postpone urination,
additional urethral closure can be elicited through somatic innervation.
 In this situation, continence relies on ctive muscle contraction, rather than
on pelvic support.
 Contraction of the striated urogenital sphincter muscle closes the
urethral lumen in its upper portion, and the compressor urethra and
urethrovaginal muscle sphincter could compress the ventral wall of the distal
third of the urethra.
 Fibers of the striated muscles involved in this process are mainly fast-twitch
fibers.
 Furthermore, when voluntary continence is needed, active contraction of the
pelvic floor may enhance urethral support but, more importantly, contraction
of the pelvic floor tends to inhibit any detrusor contraction (22).

FUNCTIONAL ANATOMY

36. Continence During Stress
 The striated urogenital sphincter by itself is not capable of
assuring continence when there is a sudden increase in
intra-abdominal pressure.
 Therefore, the transmission of abdominal pressure to the
urethra is almost certainly a primary factor in maintaining
continence during stress.
 This pressure transmission between the abdominal cavity
and the urethra is dependent on three factors:
Urethral support
Muscle synergies
Urethral compliance
FUNCTIONAL ANATOMY

37. Urethral Support
The “Hammock” Theory.
 The tissue that supports the urethra constitutes a sling
(“hammock”) under the urethra in its upper and
midportions.
 This sling is composed of a segment of the anterior
vaginal wall that is attached to the muscles of the
pelvic floor (levator ani muscles principally) and to
the arcus tendineus fascia pelvis.
FUNCTIONAL ANATOMY

38.  The levator ani muscles not only help support the
visceral structures at rest because of their constant
tone, but they act as a backup to the endopelvic
fascia, probably serving as the principal support
during suddenly increased intra-abdominal
pressure.
 The connection of the urethra to the arcus tendineus
assists levator support and limits downward descent
of the vesical neck when the levator muscles are
relaxed or overcome.
FUNCTIONAL ANATOMY

39. The “integral Theory.”
 which states that stress and urge symptoms both arise from the same
anatomical defect: a lax vagina.
The authors proposed three closure mechanisms:
1) contraction of the anterior pubococcygeus muscle closes the urethra,
and contraction of the periurethral striated muscle provides a
watertight seal for the bladder;
2)the bladder neck is closed off by being elongated backward and
downwards against an immobilized proximal urethra by stretching of
the underlying vagina;
3) a voluntary closure mechanism is mediated by the pelvic floor
muscles which, on command, pull the vaginal hammock forward.
FUNCTIONAL ANATOMY

40.  Therefore, preservation of continence necessitates
adequate functioning of the pubourethral ligament, the
suburethral vaginal hammock and the pubococcygeus
muscles.
 Tension in the pubourethral ligament is essential for a
correct interplay between the muscles and the vaginal
hammock (Fig. 5).
 The pubourethral ligament acts on an insertion point for
horizontal force at the level of the midurethra..
FUNCTIONAL ANATOMY

41.  Based on this theory, Ulmsten et al. introduced the
tension-free vaginal tape (TVT) technique which
reinforces the pubourethal ligament and the
suburethral vaginal hammock

44. Muscular Synergies
 Synchrony between the rectus abdominis muscle and the pelvic
floor.
 The posterior portion of the levator ani has constant tone but also
contracts further at the time of rectus abdominis contraction during
the Valsalva maneuver to maintain a proper vaginal axis.
 Contraction of the urethral striated muscle in addition to the
supportive role of passive compression.
 Furthermore, the greatest increase in urethral pressure occurs in the
distal urethra, rather than in the proximal urethra. This is due to the
compressor urethra and urethrovaginal sphincter muscles that
can actively raise intraurethral pressure during stress, and especially
when the patient coughs.

45. Urethral Compliance
 Urethral compliance or softness is critical for urinary
continence during stress
 When the urethra is rigid, for example, owing to scar tissue
after surgery or to pelvic radiation, the
 various continence mechanisms previously described are
not able to compress the urethra
 and to close the urethral lumen. This situation is
commonly known as intrinsic sphincteric deficiency
(ISD).
 However, there is no objective test to quantify urethral wall
compliance.