Anatomy of UI & prolapse Flashcards
What does the pelvic floor separate?
It separates the pelvic cavity (above) from the perineum (below)
What are the important functions of the pelvic floor?
It supports the pelvic organs and also helps maintain urinary & faecal continence
Name the 3 layers of the pelvic floor from (deepest to most superficial)
- Pelvic diaphragm
- Muscles of perineal pouches
- Perineal membrane
The pelvic diaphragm is the deepest layer of the pelvic floor, what is it comprised of ?
2 main muscle groups:
- Levator ani
- Coccygeus
Note the pelvic diaphragm has the appearance of a sling
What are the 2 holes of significance in the pelvic floor and why
There are 2 ‘holes’ of significance to allow for urination and defacation
- Urogenital hiatus - situated anterioly & in between the medial borders of the levator ani muscles, it allows passage of the urethra (& vagina in females)
- Rectal hiatus - a centrally positioned gap which allows passage of the anal canal
What is situated between the urogenital hiatus and the anal canal ?
The perineal body - it joins the pelvic floor to the perineum
Which of the 2 groups of muscles makes up the majority of the pelvic diaphragm?
The levator ani
What 3 muscles make up the levator ani muscle ?
- Puborectalis - U shaped sling which extends from the pubic bone, past the urogenital hiatus & around the anal canal (it is thick & chunky)
- Pubococcygeus - arises from the pubic bone & ant. aspect of the tendinous arch to attach at the coccyx (appears wide & thin)
- Iliococcygeus - arsies from ischial spines & ant. aspect of tendinous arch to attach at the coccyx
Note in the pic the other main muscle not labelled is the coccygeus muscle
Tendinous arch = thickened fascia of the obturator internus muscle
Go over the osteology of the pelvis
What is the normal disposition of the levator ani muscles and when/why does this change
They are normally tonically contracted except when they need to relax to allow urination & defacation
What is the innervation of the levator ani muscles
The peudendal nerve (S2-4) & the nerve to the levator ani (S3-5)
What are the origin and insertion points of the coccygeus muscle
It originates from the ischial spines & attaches to the lateral aspect of the sacrum & coccyx
What is the innervation of the coccygeus muscle ?
Innervated by ant. rami of S4&5
What provides additional support to the pelvic organs (alongside the pelvic floor)?
Ligaments & endo-pelvic fascia
Describe what the endo-pelvic fascia is
This is connective tissue which is almost like packaging around the pelvic organs, it provides some support but mainly allows room for pelvic organs to expand
List the different pelvic ligaments
- Utero-sacral
- Transverse cervical (most important)
- Lateral ligament of the bladder
- Lateral rectal ligaments (not in pic, so they travel from lateral aspect of rectum up towards the sacrum)
What can the perinal pouches be divided into ?
There is the deep & the superficial perineal pouches
Describe the location of the deep perineal pouch
It is located below the fascia ocvering the inferior aspect of the pelvic diaphragm & lies superior to the perineal membrane
(so it goes pelvic diaphragm → inf. aspect of covered by fascia → deep perineal pouch)
Note: Think of it in terms of standing up
What is contained within the deep perineal pouch ?
- Part of the urethra (& vagina in females)
- Bulbourethral gland in males
- neurovascular bundle for penis/clitoris
- External urethral sphincter
- Extension of ischioanal fat pads & muscles
What muscles are contained in the deep perineal pouch and state their function
- Compressor urethrae - functions to compress the urethra
- External urethral sphincter
- Deep transverse perineal muscle (contained bulbourethral gland in males)
What is the difference between the deep transverse perineal muscle in males and females ?
It is smooth muscle in females & skeletal in males
What is the function of the deep transverse perineal muscle?
- To help expel the last drops of urine (additionally explusion of semen in males)
- Since it is a pelvic floor muscle it will also contribute to supporting the pelvic organs
Where is the perineal membrane located ?
Superficial to the deep perineal pouch
What is the perineal membrane and what is its attachments ?
It is a thin sheet of tough, deep fascia which attaches laterally to the sides of the pubic arch, closing the urogenital triangle
What openings are found in the perineal membrane ?
Opening for the urethra (& vagina in females)
What together with the perineal body is the last passive support of the pelvic organs ?
The perineal membrane
Go over this pic to appreciate the layers of the pelvic floor
Note that it is looking from above down on the pelvic floor so you are seeing the pelvic diaphragm first (the deepest anatomically)
Where is the superfifical perineal pouch located ?
It lies inferior to the perineal membrane
What does the superficial perineal pouch in males contain?
- The root of the penis and its associated muscles
- Also contains proximal spongy (penile) urethra, superficial transverse perineal muscle and branches of internal pudendal vessels and pudendal nerve
What is the root of the penis comprised of and what are its associated muscles ?
Root of the penis is comprised of (erectile tissue):
- The bulb containing corpus spongiosum
- The cura cotaining corpus cavernosum
The bulb is then covered bulbospongisus muscle
The cura is then covered by ischiocavernosus muscle
What is contained within the superficial perineal pouch in females ?
- Contains female erectile tissue and associated muscle
- Also contains greater vestibular glands, superficial transverse perineal muscle and branches of internal pudendal vessels and pudendal nerve
What is the erectile tissue and associated muscles found in the superficial perineal pouch in females ?
- The cura which then join together in the midline to form the clitoris
- Bulbs (2 in females unlike 1 in males) at the base of the bulbs are the greater vestibular glands (bartholins glands)
Clitoris & cura is covered by the ischiocavernosus muscle.
Bulbs are coevered by the bulbospongiosus muscle
What is the function of the greater vestibular glands ?
To secrete mucus into the vagina to lubricate it
The muscles in the female superficial perineal pouch are much less developed than those in the males - T or F and give reasoning
True - because the male muscles need to be more developed to permit erections & ejaculation
List from deep to superficial the layers of the pelvic floor
- Levator ani
- Deep perineal pouch
- Perineal membrane
- Superficial perineal pouch
Where is the perineal body located ?
It is located at the junction of the urogenital & anal triangle - the central point of the perineum, it lies just deep to the skin
What is the function of the perineal body ?
- It acts as a point of attachment for muscle fibres from the pelvic floor & perineum.
- It is also key in support of the pelvic floor
- It acts as a tear resistant body between vagina & external anal sphincter supporting the post. part of vaginal wall against prolapses (in males it lies between the bulb of the penis & the anus)
What are the 2 main functions of the pelvic floor ?
- Provides support to the pelvic organs
- Helps maintain continence
How does the pelvic floor provide support to the pelvic organs ?
- It is normally tonically contracted to provide support. It also actively contracts anytime you raise intra-abdo pressure due to e.g. coughing, sneezing, vomiting
- They relax to allow urination & defacation
What muscles from the pelvic are specifically involved in maintaining continence ?
- Urinary; external urethral sphincter, compressor urethrae & levator ani
- Faecal; tonic contraction of puborectalis which bends the anorectum anteriorly, active contraction then maintains contience after rectal filling
What are the causes of injury to the pelvic floor ?
- Pregnancy
- Childbirth; stretching/tearing or pudendal nerve damage can all occur
- Chronic constipation
- Obesity
- Heavy lifting (e.g. body builders could be predisposed)
- Chronic cough or sneeze
- Previous injury to pelvis/pelvic floor
- Menopause
What does urinary continence depend on ?
- Urinary bladder neck support
- External urethral sphincter
- Smooth muscle in urethral wall
