Lecture 5- The pelvic floor Flashcards
what resides within the pelvic cavity
The pelvic viscera (bladder, rectum, pelvic genital organs and terminal part of the urethra)
gross structure of the pelvic floor- which muscles make ip the lateral walls?
obturator internus and piriformis
The pelvic floor is a …………..structure.
funnel-shaped
where does the pelvic floor attach to and what does it separated
It attaches to the walls of the lesser pelvis, separating the pelvic cavity from the perineum inferiorly (region which includes the genitalia and anus).
In order to allow for urination and defecation, there are a few gaps in the pelvic floor. There are two ‘holes’ that have significance:
Urogenital hiatus
Rectal hiatus
Urogenital hiatus –
an anteriorly situated gap, which allows passage of the urethra (and the vagina in females).
Rectal hiatus –
a centrally positioned gap, which allows passage of the anal canal.
Between the urogenital hiatus and the anal canal lies a fibrous node known as the ………………, which joins the pelvic floor to the perineum
perineal body
functions of the pelvic floor
- Support of abdominopelvic viscera (bladder, intestines, uterus etc.) through their tonic contraction.
- Resistance to increases in intra-pelvic/abdominal pressure during activities such as coughing or lifting heavy objects.
- Urinary and faecal continence/defaecation/ micturition. The muscle fibres have a sphincter action on the rectum and urethra. They relax to allow urination and defecation.
- Faciliatate child birth
3 main components of the pelvic floor (muscles)
Levator ani muscles (largest component).
Coccygeus muscle.
Fascia coverings of the muscles.
Levator Ani Muscles- Innervated by
the anterior ramus of S4 and branches of the pudendal nerve (roots S2, S3 and S4).
what sort of muscles are the leavtor ani muscles
broad sheet of muscle
Levator Ani Muscles composed of
three spearate paired muscles
- pubococcygeys
- puborectalis
- iliococcygeus
Levator Ani Muscles attachments : anteior
pubic bodies of the pelvic bones
Levator Ani Muscles attachments: laterally
thickened fascia of the obturator internus muscle, known as the tendinous arch.
levator ani muscle attachments: posteriorly
the puborectalis muscle is a
U-shaped sling
where does the puborectalis muscle extend
from the bodies of the pubic bones, past the urogenital hiatus, around the anal canal.
tonic contraction of the puborectalis
bends the canal anteriorly, creating the anorectal angle (90 degrees) at the anorectal junction(where the rectum meets the anus).
if tonic cotnraction bends the canal anteriorly (creating an anorectal angle of 90 degrees) what is the main function of the puborectalis
The main function of this thick muscle is to maintain faecal continence – during defecation this muscle relaxes.
puborectalis also includes
pre-rectal fibres
Some fibers of the puborectalis muscle (pre-rectal fibers) form another U-shaped sling that flank the urethra in the male and the urethra and vagina in the female (in some textbooks they appear as pubovaginalis or sphincter urethrae / vaginae).
pre-rectal firbes of the puborectalis are important in
These fibers are very important in preserving urinary continence, especially during abrupt increase of the intra-abdominal pressure i.e. during sneezing.
Pubococcygeus
The muscle fibres of the pubococcygeus are the main constituent of the levator ani.
where does rhe pubococcygeus muscle arise from
arise from the body of the pubic bone and the anterior aspect of the tendinous arch.
The fibres travel around the margin of the urogenital hiatus and run posteromedially, attaching at the coccyx and anococcygeal ligament.
