Pelvis and Perineum Flashcards
Prostate in relation to rectum?
Prostate is anterior to rectum
In men does the ductus deferens cross the ureter?
Yes
2 important angles of the urethra?
Bends anteriorly via perineum
In external penis where it droops
What is the perineum innervated by?
S3-S5
Rectum is S5 in both genders
In men S3 = penis and scrote
Which ligaments support the lumbosacral joint
iliolumbar and lumbosacral - both attach to transverse process of L5
Which three ligaments support the sacro-iliac joint?
Anterior sacro-iliac = thickening of fibrous membrane from joint capsule
Interosseous ligament = strongest. Positioned poster-superior
Posterior sacro-iliac ligament = covers interosseous ligament
Which ligaments does the pelvic wall have?
What is so important about them?
Sacrospinous = attaches to margin of sacrum/coccyx, inserting on ischial spine
Sacrotuberous = Broad base attaches to PSIS + along sacrum/coccyx. Inserts ischial tuberosity
- This is superficial to the sacrospinous
These ligaments turn the sciatic notches into foramen
Which muscle divides the greater sciatic notch into 2?
Piriformis
What passes via obturator canal?
Obturator nerve and vessels
What passes through greater sciatic foramen?
Above piriformis = superior gluteal vessels and nerve
Below piriformis = inferior gluteal nerve and vessels, Pudendal nerve + internal pudendal vessels, then 4 more nerves: Sciatic nerve Posterior femoral cutaneous nerve Nerve to quadratus femoris Nerve to Obturator internus
What passes through lesser sciatic foramen?
Tendon of obturator internus
Pudendal nerve and internal pudendal vessels
Which muscles make up the pelvic floor?
Levator ani = pubococcygeus, puborectalis and iliococcygeus
Coccygeus
Pelvic floor muscles - origin, insertion + innervation
- Pubococcygeus:
Origin = inner pubis and obturator fascia
Insertion = Fuses medially at perineal body, attaches to coccyx and anococcygeal ligament. - Iliococcygeus:
Origin = Coccyx and anococcygeal ligament . Posterolaterally attaches to ischial spine and along tendinous arch of obturator fascia.
Insertion = Anteromedially fuses with pubococcygeus - Puborectalis:
Origin = Extends from pubic bone
Insertion = Forms U-shaped sling around anal canal.
INFERIOR RECTAL BRANCH OF PUDENDAL
Coccygeus - pulls coccyx forward post defecation
Origin = ischial spine + pelvic surface of sacrospinous ligament
Insertion = Lateral margin of coccyx
ANTERIOR RAMI OF S3/S4
What innervates the muscles of the deep pouch?
Perineal branch of pudendal nerves
Which parts of the rectum are extraperitoneal?
what surrounds the extraperitoneal parts of the rectum and why is this clinically significant?
Posterior upper third
Posterolateral middle third
Whole lower third
Surrounded by mesorectal fat = has LN’s
So must be dissected out if rectal cancer.
What level does sigmoid colon form rectum?
L3
What are the two fascial layers of the rectum?
Fascia of Denonvilliers = anterior = separates rectum and prostate
Waldeyers fascia = posterior = separates rectum and sacrum
- this must be dissected to mobilise mesorectum from sacrum and coccyx in LAR
Arterial supply to rectum?
Venous drainage?
SRA from IMA
MRA from internal iliac
IRA from internal pudendal
Superior rectal vein
Lymphatic drainage of the rectum?
Upper part = mesenteric
Lower part = internal iliac
Where does anal canal begin and stop?
From levator ani to anal verge
What is the structure and cell type of the upper 2/3rds of the anal canal?
Artery and vein?
Columnar epithelium
6-10 longitudinal folds = columns of Morgagni
At the bottom of these = sinuses
3 major sinuses at 3, 7 and 11-o-clock where major arteries feed the vascular plexi
Superior rectal artery and vein
Does the upper 2/3rds of the anal canal have sensation?
What is its lymphatic drainage?
No sensation
Internal iliac nodes
What is the anal transitional zone?
Area between columnar and squamous zones
= dentate line
Lower third of the anal canal - cell type, sensation, vasculature and lymphatics?
Non-keratinsing squamous epithelium = NO GLANDS
Exquisitely sensitive
Middle and inferior rectal arteries and veins
Superficial inguinal LN’s
Internal vs external anal sphincter?
Internal = smooth muscle continuous with the circular muscle of rectum
- surrounds upper 2/3rds of canal
- sympathetic nerve supply
External = striated muscle which also surrounds internal one but extends more distally
- S234: S2/3 = inferior rectal branch of pudendal, S4 = perineal branch
Embryologically where does the ureter develop from?
Out-pouching of the mesonephric duct in embryo
Are the ureters intra or retroperitoneal?
Retro
What crosses the ureter?
Men = ductus deferens Women = uterine artery
Relation of ureter to bifurcation of iliacs?
Anterior
Arterial supply of the ureter?
Proximal = renal arteries Middle = aortic branches, gonadal branches and common iliacs Distal = Internal iliac
Lymphatic drainage of ureter?
upper = para-aortic nodes Lower = common iliac does
What is connected to the apex of the bladder?
What is this a remnant of?
Median umbilical ligament = ascends superiorly to umbilicus
Embryological remnant of urachus
Is bladder retroperitoneal?
Clinical significance ?
Yes, although peritoneum is draped on the top of it
As bladder distends it will separate transversalis fascia from peritoneum = can use suprapubic catheter without penetrating peritoneum.
What fixes the neck of the bladder in place?
Men = Puboprostatic ligament Women = pubovesical
Arterial supply to bladder?
Venous supply to bladder?
Inferior and superior vesicle arteries = branch of internal iliacs
Venous:
Men = vesicoprostatic plexus
Women = Vesicouterine plexus
Lymphatics of the bladder?
Mainly external iliac nodes
Female urethra: External urethral sphincter innervation + lymphatic drainage ?
Pudendal nerve
Whole female urethra drains to the internal iliac nodes
Four parts of the male urethra?
- pre-prostatic
- Between bladder and prostate, stellate lumen
- only about 2cm long
- Has striated muscle to prevent retrograde ejaculation = internal sphincter - Prostatic part:
- surrounded by prostate
- midway has circular elevation = seminal colliculus - Membranous part:
- Narrowest part
- surrounded by external sphincter = first point of resistance
- traverse perineal membrane - Spongy part / penile part:
- Travels through corpus spongiosum
- covered by bucks fascia
- Dilated at origin as infrabulbar fossa, dilated at navicular fossa too in glans of penis
Which section of male urethra is covered in bucks fascia?
Penile / spongy part
Which part of male urethra has the internal and external sphincter?
Muscle type?
Pre-prostatic = internal = striated muscle
Membranous = external
Lymphatic drainage of male urethra?
Penile / spongy part = deep inguinal
Prostatic / membranous = internal iliac
What peritoneal pouch is formed where the peritoneum sits between the bladder and uterus?
Vesicouterine pouch
What pouch forms where the peritoneum sits between the rectum and uterus?
Recto-uterine pouch / POUCH OF DOUGLAS
What is the ligament called, formed by the large fold of peritoneum lateral to each uterus?
Broad ligament
What are the 3 parts to the broad ligament?
Mesometrium = extends from lateral pelvic wall to the uterus
Mesosalpinx = suspends uterine tubes
Mesovarium = Posterior extension attaching to ovaries
What is the suspensory ligament of the ovary called?
What does it contain?
Infundibulopelvic ligament
Ovarian vessels, nerves and lymphatics = all enter at superior pole
What ligament attaches to the inferior pole of the ovary?
What does this ligament continue as within the broad ligament?
Ligament of ovary
This continues anterolaterally in the broad ligament as ROUND LIGAMENT OF UTERUS