Wednesday, April 4, 2012

Components of continence mechanism in females- 3-Pelvic floor

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 



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