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Pelvic Floor AnatomyPelvic Floor Anatomy
Colorectal ConferenceColorectal Conference
7/21/057/21/05
Peter M. Kaye, M.D.Peter M. Kaye, M.D.
The Pelvic FloorThe Pelvic Floor
Musculotendinous Musculotendinous hammock or slinghammock or sling
Termination of the Termination of the pelvic outletpelvic outlet
Muscles of the pelvisMuscles of the pelvis Anal sphincter complexAnal sphincter complex Levator ani musclesLevator ani muscles
Support the abdominal Support the abdominal and pelvic organsand pelvic organs
Connect the pelvis to Connect the pelvis to the vertebral columnthe vertebral column
Maintain continenceMaintain continence
Anal Sphincter ComplexAnal Sphincter Complex
Internal anal sphincterInternal anal sphincter Conjoined longitudinal muscleConjoined longitudinal muscle External anal sphincterExternal anal sphincter
Internal Anal SphincterInternal Anal Sphincter
Extension of the circular muscle Extension of the circular muscle layer of the rectumlayer of the rectum
Constant maximal contractionConstant maximal contraction 50-85% of resting anal tone 50-85% of resting anal tone Autonomic innervationAutonomic innervation
Parasympathetic…..S2-4Parasympathetic…..S2-4 Sympathetic……..thoracolumbar Sympathetic……..thoracolumbar
ganglia (L5)ganglia (L5) Suggested that both Suggested that both
parasympathetic and parasympathetic and sympathetic innervation cause sympathetic innervation cause inhibition of contractioninhibition of contraction
Conjoined Longitudinal Conjoined Longitudinal MuscleMuscle
Extension of the Extension of the longitudinal muscle longitudinal muscle layer of the rectum, layer of the rectum, along with levator ani along with levator ani muscle fibersmuscle fibers
Structural support, Structural support, anchoring the anchoring the anorectum to the anorectum to the pelvispelvis
External Anal SphincterExternal Anal Sphincter
Multiple layers of Multiple layers of striated musclestriated muscle
Voluntary contractions Voluntary contractions to prevent fecal leakto prevent fecal leak
25-30% of resting anal 25-30% of resting anal tonetone
Somatic innervation Somatic innervation from the inferior rectal from the inferior rectal branch of the pudendal branch of the pudendal nerve (S2-3) and the nerve (S2-3) and the perineal branch of S4perineal branch of S4
Levator Ani MusclesLevator Ani Muscles
PubococcygeusPubococcygeus IliococcygeusIliococcygeus PuborectalisPuborectalis IschiococcygeusIschiococcygeus
PuborectalisPuborectalis
U-shaped, medial U-shaped, medial most located levator most located levator ani muscleani muscle
Pulls the anorectal Pulls the anorectal junction anteriorly, junction anteriorly, forming the forming the anorectal angleanorectal angle
Pelvic floor muscle Pelvic floor muscle vs. sphincter vs. sphincter muscle?muscle?
Functional AnatomyFunctional Anatomy
Puborectalis and the anorectal angle allow Puborectalis and the anorectal angle allow for gross fecal continencefor gross fecal continence
Relieves pressure from the sphincter Relieves pressure from the sphincter processprocess
The sphinter complex is responsible for The sphinter complex is responsible for gas and liquid continencegas and liquid continence
DefecationDefecation Relaxation of the puborectalisRelaxation of the puborectalis Contraction of the other levator musclesContraction of the other levator muscles
Functional AnatomyFunctional Anatomy
Rectal prolapseRectal prolapse Laxity in sphincter Laxity in sphincter
complex and complex and levator muscleslevator muscles