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- autonomic
Membranous = external- somatic
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
What is the main structural support of the uterus?
Central perineal tendon.
Fascia of the cervix?
Pubocervical ligament = cervix to anterior pelvic wall
Transverse cervical / cardinal = cervix to lateral pelvic wall
- most important in stabilisation!!
Uterosacral = Cervix to posterior pelvic wall
Lymphatic drainage of the vagina?
Superior = iliac nodes
Inferior = superficial nodes
Organ sites that metastasise to para-aortic LN’s early?
Testis
Ovaries
Uterine fundus
Lymphatic drainage of uterus, ovaries and cervix ?
Ovaries and uterine fundus = para-arotic via gonadal vessels
Uterine body = Iliac LN’s via broad ligament
Cervix = iliacs
Blood supply of uterus?
Uterine artery = branch of internal iliac
3 arteries, 3 nerves and 3 others of the spermatic cord PLUS where they come from / what they do?
Arteries:
- Testicular artery = branch of abdominal aorta, supplies testis and epididymis
- Cremasteric artery = from inferior epigastric
- Artery of vas. deferens = arises from inferior vesicle artery
Nerve:
- Sympathetic = lie on the arteries
- Genital of GF = supplies cremaster
(3. ilioinguinal)
Other:
- Vas deferens = transmits sperm and accessory gland secretion
- Pampiform plexus = venous plexus, drains into R or L testicular vein
- Lymphatics - to lumbar or para-aortics
Testes embryology - where do they start, where in 3rd month, where at 7th month?
Posterior wall L2
third month = iliac fossa
7th = deep inguinal ring
What surrounds the testis?
Tunica vaginalis
The parietal layer is adjacent to the internal spermatic fascia
What is the tunica vaginalis derived from?
Peritoneum
What surrounds the seminiferous tubules and interstitial tissue?
What do the seminiferous tubules form and what does this lead to
Tunica albuginea
Seminiferous tubules form retes testis
this then leads to efferent ductules > head of epididymis
Artery and venous supply of testis?
Testicular artery arises from aorta just below renal arteries
Pampiform plexus
L goes to left renal
R directly to IVC
LN’s of the testis?
Para-aortic
Course of the vas deferens?
Ascends in scrotum then passes through inguinal canal exiting deep ring
Then bends medially around inferior epigastric artery
Crosses external iliac vein and artery to enter pelvic inlet
Crosses ureter
Joined by seminal vesicle = ejaculatoy duct
Penetrates prostate and feeds into prostatic part of urethra
Arterial supply of scrotum?
Lymphatic drainage?
Sensory innervation?
Anterior and posteiror scrotal arteries
Inguinal’s
Anterior = ilioinguinal
Posterior - pudendal
Layers you cut through in scrotal surgery?
Skin Dartos fascia External spermatic fascia Cremasteric fascia / muscle Internal spermatic fascia Parietal layer of tunica vaginalis
Where do the posteiror and median lobes of the prostate sit in relation to the urethra?
Posterior
What separates the rectum and prostate?
Denonvilliers fascia
Prostate - arterial supply, venous supply + LN’s?
Innervation of prostate?
Inferior vesical artery from internal iliac
Prostatic venous plexus
Internal iliac LN’s
Inferior hypogastric plexus
Which roots make up the lumbar plexus?
L1-L3 + part of L4
Ilioinguinal nerve - root and course?
L1
Descends around abdominal wall in plane between transversus abdominus and internal oblique
Then passes via inguinal canal
Ilioinguinal nerve - innervation?
No motor function in thigh, but innervates abdominal wall muscles
Sensory = anteromedial thigh and adjacent perineum
Genitofemoral nerve - root and course?
L1/L2
Descends anteroinferiorly through the psoas muscle, then passes on the anterior surface of psoas
Femoral branch passes under inguinal ligament
Genital branch enters inguinal canal
Genitofemoral nerve - innervation?
No motor, but in men genital branch innervates cremasteric muscle of spermatic cord
Sensory:
Genital = anterior perineum
Femoral = anterior central upper thigh
Femoral nerve - root and course?
L2-L4
Passes through gap between inguinal ligament and pelvic bone
Enters femoral triangle
Innervation of femoral nerve?
Motor = anterior thigh, illiacus and pectineus
Sensory = Anterior thigh, anteromedial knee + medial leg/foot
Obturator nerve - root and course?
L2-L4
travels within the psoas major, and emerges from medial part
Passes posterior to common iliac artery, medial to internal iliac artery
Passes through obturator canal
Obturator nerve innervation?
Medial muscles of thigh EXCEPT adductor magnus head attached to ischium + pectineus
Also innervates obturator internus
Sensory = upper medial thigh
Lateral cutaneous nerve - root and path?
L2, L3
Passes between inguinal ligament and pelvic bone
Lateral cutaneous nerve innervation?
Parietal peritoneum in RIF
Anterolateral thigh.
What makes up the sacral plexus?
Anterior rami of S1-S4
Lumbosacral trunk = L4/L5
What muscle is the sacral plexus formed anteriorly too?
Piriformis muscle
Sciatic nerve - roots and course?
L4-S3
Leaves pelvis via greater sciatic foramen, inferior to piriformis
Descends between superficial and deep gluteal muscles
Then passes into gluteal region = Common peroneal and tibial
What does common peroneal supply vs tibial nerve?
Common peroneal:
Motor = short head of biceps, anterior and lateral leg compartments
Also extensor digitorum brevis + contributes to first dorsal interossei
Sensory = Skin on anterolateral leg and dorsal foot
Tibial:
Motor = Posteiror hamstrings EXCEPT short head of biceps, posterior compartment of the leg, muscles in sole of the foot
Sensory = Posterolateral and medial foot + sole of foot
Pudendal nerve - roots and course?
S2-S4
Leaves pelvis below piriformis, via greater sciatic foramen
Immediately curves around the sacrospinous ligament where it joins ischial spine, and passes via the lesser sciatic foramen
Accompanied by internal pudendal vessels
What does pudendal nerve innervate?
Skin and muscles of perineum
Includes external urethral sphincter + anal sphincter and levator ani
Sensory = Skin of perineum + penis / clitoris
Superior gluteal nerve - roots and course?
L4-S1
Leaves greater sciatic foramen above the piriformis
Travels in plane between gluteus medium and minimum
What does superior gluteal nerve supply?
Gluteus medius and minimus
Terminates innervating tensor fascia lata
Inferior gluteal nerve - roots and course?
L5-S2
Leaves pelvic cavity via greater sciatic foramen below piriformis
Penetrates gluteus maximus
Inferior gluteal nerve supplies?
Gluteus maximus
Nerve to obturator internus and superior gemellus - roots and course?
L5-S2
Leaves via greater sciatic foramen inferior to piriformis. Then passes around ischial spine and via lesser sciatic foramen
Nerve to quadratus femoris and inferior gemellus - roots and course?
L4 - S1
Greater sciatic foramen, inferior to piriformis
Passes anterior to plane of deep gluteal muscles
Posterior cutaneous nerves - roots and course?
S1, S3
Leaves via greater sciatic foramen inferior to piriformis
Immediately medial to sciatic nerve
Descends through gluteal region deep to gluteus maximus
Posteiror cutaneous nerve innervation?
Skin on posterior thigh
Perforating cutaneous nerve - root and course?
S2, S3
Unusual route and penetrates directly through sacrotuberous ligament to reach inferior buttocks
Perforating cutaneous nerve innervation?
Skin over gluteal fold
How does the nerve to piriformis leave the pelvic cavity?
It doesn’t, oiiiii
Hypogastric plexus - route and what it eventually innervates?
Starts as superior hypogastric plexus anterior to L5, near aortic bifurcation
Enters pelvis as 2 hypogastric nerves. Crosses pelvic inlet medial to internal iliac vessels
Forms inferior hypogastric plexus when hypogastric nerves are joined by the splanchnic nerves
Inferior hypogastric plexus gives rise too: Rectal plexus Uterovaginal plexus Prostatic plexus Vesical plexus
Terminal branches innervate erectile tissue of penis/clitoris
Penile erection - parasympathetic vs sympathetic innervation?
Parasymp = erection Sympathetic = Ejaculation and detumescence
Penile erection - which are the somatic nerves, what nucleus they relay from and muscles innervated?
Dorsal penile and pudendal
Efferent fibres via Onuf’s nucleus
Ischiocavernous and bulbocavernous
Where does internal iliac originate, and where does it divide into anterior and posteiror trunk?
Originates at L5/S1 just anterior to the sacroiliac joint
Divides into posterior and anterior trunks at superior border of greater sciatic foramen
Internal iliac posterior trunk - branches and supply?
Iliolumbar:
- Divides into iliac and lumbar branch
- iliac = skin and muscles in RIF
Lumbar = psoas and quadratus lumborum
Lateral sacral:
- Medial and inferior branches
- Supply muscle and skin behind sacrum
Superior gluteal:
- leaves pelvic cavity above piriformis via greater sciatic foramen
- Divides into superficial and deep branches
- Deep travels between medium and minimus
- superficial Passes on deep surface of maximus
Anterior trunk branches of internal iliac artery?
Umbilical Superior vesical Inferior vesical (men) - vaginal artery in women = equivalent Inferior gluteal Middle rectal Internal pudendal Obturator Uterine (women)
Anterior trunk of internal iliac - Umbillical
Path
Embryology
Continues inferiorly before ascending on anterior abdominal wall to reach umbilicus
In foetus it is very large, in adults it becomes a fibrous cord
This cord is called medial umbilical ligament
Anterior trunk of internal iliac - superior vesical
What does it supply?
Superior aspect of bladder and distal ureter
In men also supplies ductus deferens
Anterior trunk of internal iliac - inferior vesical
Men or women?
What it supplies?
Men
Female equivalent = vaginal artery
Bladder ureter, seminal vesicle and prostate / vagina
Anterior trunk of internal iliac - Obturator artery
Path and supply?
Leaves pelvis via obturator canal
Supplies adductor region
Anterior trunk of internal iliac - Internal pudendal
Path and supply?
Greater sciatic foramen then the lesser sciatic foramen passing over sacrospinous ligament as it joins ischial spine
Erectile tissue
Anterior trunk of internal iliac - inferior gluteal
Path
Passes between anterior rami of S1/S2/S3
Leaves greater sciatic foramen inferior to piriformis
Anterior trunk of internal iliac - Uterine artery
Path
Supply
what it anastomoses with
Travels medially in base of the broad ligament to reach cervix
Crosses ureter and passes superior to lateral vaginal fornix
Anastomoses with. ovarian artery
What are the ovarian arteries a branch of and what do they travel in?
Branch of aorta
Travel in suspense sort ligament of the ovaries = infundibulopelvic ligament
Whats the vein draining clitoris / penis?
Single deep dorsal vein
Left vs right ovarian vein drainage?
Left into renal vein
Right into IVC
Borders of the perineum?
tip of coccyx posteriorly
Pubic symphysis anteriorly
Laterally = ischiopubic ramus anteriorly, sacrotuberous ligament posteriorly
Roof = levator ani
How do we divide the perineum into two?
line between two ischial tuberosities
Anterior = urogenital triangle
Posteiror = anal triangle
Contents of anal triangle?
External anal sphincter = S234
Contents of urogenital triangle?
Males = bulb and crura of penis, superficial transverse perineal muscles and posteiror scrotal arteries and nerves
Females = Internal pudendal becomes posteiror labial artery, Muscles again, crura of clitoris, greater vestibular gland
Three branches of the pudendal nerve and what they innervate?
Infeiror rectal = external anal sphincter + skin of anal triangle
Perineal = Skeletal muscles in perineal pouch + branches into scrotal / labial nerves
Dorsal nerve of penis / clitoris = sensory
As the internal pudendal artery and pudendal nerve pass around ischial spine, which lies lateral?
Artery lies lateral
Where do the testicular artery and cremasteric artery branch from?
Testicular = aorta Cremasteric = from the infeiror epigastric of the external iliac
Layers of spermatic cord?
Internal spermatic fascia = Transversalis fascia
Cremasteric fascia = Internal oblique
External spermatic fascia = External oblique
