2.2 Pelvic floor and perineum Flashcards
What fills the lower part of the pelvic canal and closes the abdominal cavity
Give its main functions
The Pelvic floor: a muscular and fibrous tissue diaphragm comprised of muscle and fascia
Functions to supports and lifts the pelvic organs
- has a role in childbirth, continence
What 3 bony structures mark the pelvic inlet?
1) broad ‘wings’ of the iliac bones
2) the sacrum
3) the pubic symphysis
What 3 bony structures mark the pelvic outlet?
1) paired inferior pubic rami
2) the ischial bones and ischial spines
3) the coccyx
In the erect position what angle is the pelvic inlet to the horizonal?
In the erect position, the pelvis is tilted so that the plane of its inlet is at an angle of 60o to the horizontal
Which image shows the male vs female bony pelvis?
Compare the two and give 3 features of each
Female (left):
- Circular pelvic inlet
- Pubic arch angle wider (80-85°)
- Less distinct sacral promontory (furthur back)
- Broader alae (wings)
Male (right):
- Heart shaped pelvic inlet
- Pubic arch angle smaller (50-60°)
- Ischial spines project more medially into pelvic cavity
What is the “false” vs the “true” pelvis?
False (Greater):
- related to upper parts of the pelvic bones, considered part of abdomen
- extends from pelvic inlet to top of iliac crest
True (Lesser):
- Boundaries: pubic symphysis, pelvic brim, sacral promontory
- has a Inlet superiorly and an outlet inferiorly
- reproductive organs reside here
Where is the perineum located in relation to the true pelvis?
What 2 important openings are found here?
Inferior to true pelvis
It is the area where the external genitalia and openings of GI system/genitourinary system are found
What structure defines the upper boarder of the perineum?
The pelvic floor
What sperates the true pelvis above from the perineum below?
Pelvic floor muscles (the pelvic diaphragm)
How to structures pass between the pelvic cavity and the abdomen?
through the pelvic inlet
What 2 ligaments define the posterior half of the pelvic OUTLET?
What bones define the anterior half of the pelvic INLET and what significance does this have?
Sacrotuberous ligament and Sacrospinous ligament define the outlet
The bones of the inlet are the Ishiopubic rami
Important in both males and females as the external genitialia (clitorus/penis) are anchored to the bony margins of the anterior half of the pelvic outlet
List 3 structures that pierce the pelvic floor
urethra, vagina (in females), and rectum
Lable the diagram
The pelvic floor provides a diaphragm across the outlet of the true pelvis
what are the 2 main layers of the pelvic floor?
How can these be furthur divided?
1) The pelvic diaphragm:
- Levator Ani (pubococcygeus, iliococcygeus and puborectalis)
- Coccygeus
2) Perineum: diamond shaped space with 2 triangular regions:
- Anterior (Urogenital) Triangle
- Posterior (Anal) Triangle
How is the Anterior (Urogenital) Triangle (of the perineum) divided into 2 layers?
How can these be futhur divided?
1) Urogenital Diaphragm (which has 2 layers):
- Deep perineal pouch
- Perineal membrane
2) Superficial perineal pouch
* This is the layer where the roots of the external genitalia reside
What 3 structures can be found within the deep perineal pouch that are found in both sexes?
1) Openings for the urethra
2) External urethral sphincter
3) Deep transverse perineal muscle
What is the perineal membrane and where is it located
where does it attach from/too and what does this seperate?
The perineal membrane is a thick triangular fascial sheet located inferior to the pelvic floor and deep perineal pouch
attaches laterally to the inferior pubic rami and has a gap anteriorly (does not reach pubic symphysis). It also has a free posterior boarder
Forms boundary between the deep perineal pouch and the superficial perineal pouch
What is found within the superficial perineal pouch in both sexes
Muscles:
- superficial transverse perineal muscle
- bulbospongiosus
- Ischiocavernosus
- perineal body (not a muscle)
One nerve and one artery:
- branches of the internal pudendal artery
- the perineal nerve
Give 2 additonal structures found in the superficial perineal pouch specific to males vs females
males: bulb of the penis and crus of the penis
females: bartholins glands (greater v glands) and crus of the clitoris
Which image shows the male vs female deep perineal pouch?
Compare features of each (DOBE DONEx2)
MalesDOBE (image B)
- Deep Transverse Perineal Muscle
- Opening for urethra
- Bulbourethral glands
- External urethral sphincter
FemaleDONEx2 (image A)
- Deep Transverse Perineal Muscle
- Opening for urethra
- No Glands
- External urethral sphincter
- x2 additional muscles: sphincter urethrovaginalis and compressor urethra
Where is the superficial perineal pouch located in relation to the perineal membrane?
Inferior to it
What is meant by “roots of the external genitalia”?
How does this differ in males and females?
The roots of the external genitalia are Bulbospongiosus and
Ischiocavernosus muscle
In males:
- the Bulbospongiosus is the root of the penis
- the Ischiocavernosus muscle is the crus/body of the penis
In females:
- the Bulbospongiosus is the bulb of vestibule of the vagina
- the Ischiocavernosus muscle is the crus of the clitoris
What is the perineal body and what is its function
Give one muscle that intersects here and give 3 muscles that attach here
It is a connective tissue structure that acts as a central fulcrum for pelvic support. It is situated in the midline, along the posterior boarder of perineal membrane
Muscles: deep transverse perineal muscles INTERSECT here
Other muscle connect here:
- external anal sphincter
- superficial transverse perineal muscles
- bulbospongiosus muscles of perineum
How may the perineal body commonly be damaged?
How may this be avoided?
Perineal body commonly damaged in childbirth which causes weakness in the pelvic floor and can lead prolapse of the vagina or uterus
This might be avoided by episiotomy
