What is the pelvic floor?
A muscular and fibrous tissue diaphragm
Where is the pelvic floor?
It fills the lower part of the pelvic canal, and closes the abdominal cavity
What does the pelvic floor define?
The upper border of the perineum
What does the pelvic floor support?
The pelvic organs
What is the pelvic floor pierced by?
How are the structures piercing the pelvic floor held closed at rest?
By muscle tone
What can the pelvic floor be split into?
- Pelvic diaphragm
- Superficial muscles and structures
What does the pelvic diaphragm consist of?
Levator ani and cocygeus, and related fascial coverings
What are the superficial muscles and structures of the pelvic wall?
- Anterior/urogenital perineum
- Posterior/anal perineum
What is the pelvic side wall made up of?
- Ischium of pelvis
- Sacrospinous and sacrotuberous ligaments
- Obturator membrane
- Obturator nerve
- Obturator internus
- Piriformis and coccygeus
- Branches of sacral plexus
- -Fascia (includes arcus tendineus)
- Levator ani muscles
- Internal iliac vessels and branches
What happens to the fascia of the obturator internus?
It condenses to become the origin of the levator ani
What is the pelvic floor made up of?
- Levator ani
Where does the levator ani originate from?
From the posterior aspect of the pubic bone, the fascia over the obturator internus, and ischial spine
Where do the anterior fibres of the levator ani attach?
Around the prostate or vagina
Where do the intermediate fibres of the levator ani go?
Around rectum (puborectalis) and into anococcygeal body (pubococcygeus)
Where do the posterior fibres of the levator ani attach?
Anococcygeal body and coccyx (iliococcygeus)
What does the coccygeus lie over posteriorly?
The sacrospinous ligament
What is the pelvic floor attached to?
The pelvic side wall
Where is the pelvic floor attached to the pelvic side wall?
At the ischial spine and the arcus tendineus fascia pelvis
What is the purpose of the urogenital hiatus in the pelvic floor?
It allows passage of urethra, vagina, and rectum
What is found between the levator ani and the perineum?
The ischiorectal fossa
What is the ischiorectal fossa continuous with?
- The perineal space
- Ischiorectal fat of buttocks
What is the result of the ischiorectal fossa being continuous with the perineal space?
- Perineal/buttock abscesses can spread, causing inflammation in the pelvis
- Infection in the pelvis can track to the buttocks
What passes along the lateral wall of the ischiorectal fossa?
The pudendal nerve
Where can the subperitoneal space be seen?
Above the levator ani muscles, but below the peritoneum
What is the importance of the subperitoneal space?
- It is where the uterine artery enters
- Ureters pass through the space
- Lymphatic drainage from the uterus and cervix leaves through here
What is the posterior vaginal wall associated with?
The rectum (lower 1/3 to the top)
What is the anterior vaginal wall associated with?
The urethra and bladder
What is the posterior fornix in contact with?
The peritoneal cavity
What blood vessels run in the pelvic floor?
- Branches of the anterior trunk of the internal iliac artery
- Ovarian artery
- Uterine artery
What are the branches of the anterior trunk of the internal iliac artery?
- Pudendal artery
- Vaginal artery
- Inferior rectal artery
Where does the ovarian artery come from?
Directly from the abdominal aorta
What is found above the ovarian vessels?
An extension of peritoneum, called the suspensory ligament/infundibulopelvic ligament, which spans between the pelvic brim and ovary
What is the uterine artery inside?
The transverse cervical ligament
Which nerve is important in the pelvic floor?
Pudendal nerve (S2, 3, 4)
Where does bifurcation of the aorta occur?
In front of the sacral promontory
What are the functions of the pelvic floor?
- Supports pelvic organs
- Contributes to continence
- Contributes to process of childbirth
- Contributes to truncal stability
How does the pelvic floor contribute to continence?
Allows sphincter pressure to resist bladder pressure, thus sphincter mechanism is direct and indirect
How does the pelvic floor contribute to the process of childbirth?
Pressure from the body moving down, and the shape of the pelvic floor means that they baby rotates for delivery of the shoulder
How does the pelvic floor contribute to truncal stability?
Gives a muscle tone for the abdominal pressure to press against
What do the pelvic floor muscles do at rest?
- Pull urethra against pubic symphysis
- Faecal continence, until ready to reflex where the pelvic floor then relaxes
How do the pelvic floor muscles contribute to faecal continence when at rest?
They pull the anorectal flexure anteriorly (90 degrees)
What are the main muscles of the pelvic floor?
- The levator ani
What is the levator ani made up of?
Where are the ischocavernosus and bulbiospongiosus found?
In the anterior section of the pelvic floor
What is the perineum?
A fibromuscular sheet
What does the perineum do?
Closes the pelvic outlet
What does the perineum form?
The lower limit of the perineal space
Where is the perineum located?
Between the levator muscles and inferior skin
What is the perineal space continuous with?
The ischiorectal fossa
What is the perineum made up of?
- Perineal muscles
- Perineal body
What is the perineal body made up of?
- Urogenital diaphragm
- Transverse perineal muscles
Where is the anterior/urogenital diaphragm?
It fills the gap of the pubic arch, stretching between the converging ischiopubic rami
Describe the structure of the anterior/urogenital diaphragm
It is a triangular sandwich with striated muscle fibres between 2 layers of fascia (superior fascia, sphincter urethrae, inferior/superior facsia)
What is the posterior triangle/anal perineum?
A triangle between the ischial tuberosities on each side, and the coccyx
What does the anal perineum comprise?
- Levator ani
- Ischiorectal fossa
Why may long distance cyclists can erectile dysfunction?
Because they can compress their pudendal nerves
What is the clinical relevance of the superficial perineal pouch?
It is the site of collection of urine if the urethra is ruptured below the perineal membrane
What is the perineal body>
The connective tissue mass in the centre of the perineum
What does the perineal body do?
- Anchors the perineal muscles and the rectum
- Acts as a central fulcrum for pelvic support
What does the perineal body form?
Part of level 3 of endopelvic fascia levels of support
What is level 1 of endopelvic fascia support?
Uterus iwth its uterosacral ligament
What is level 2 of endopelvic fascia support?
Fascial layers (acrus tendineus)
What is level 3 of endopelvic fascial support?
- Perineal body
- Perineal membrane
With respect to endopelvic fascial support, what can happen in a prolapse?
- Loss from level 1 - all falls down
- Fascia on level 2 can break
- Poor repair of perineal body, such as after childbirth, can cause prolapse
What is the most common type of prolapse?