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Flashcards in S&F Part III Deck (67):
1

What are the layers of the anterolateral abdominal wall?

1) Skin
2) superficial fascia
2a- camper's fascia- fatty layer
2b- scarpa's fascia - inner fibrous layer (becomes dartos fascia of penis/scrotum and colle's fascia of perineum)
3) external oblique layer- muscle, aponeurosis, fascia
4) internal oblique layer- muscle, aponeurosis, fascia
5) transversus abdominis- muscle, aponeurosis, fascia
6) transversalis fascia (inner surface of abdominal wall)
7) extraperitoneal fatty layer
8) parietal peritonem

2

What is the relationship of the scrotum to the anterior abdominal wall?

Scrotum starts out at 7- extraperitoneal layer
descent of testis - goes from 7 to 2- dartos fascia
*no fatty layer (campers fascia) in scrotum- this is because scrotum is kept cooler for spermatogenesis, don't want insulating layer; this is why testis ends up in scrotum even though it starts in abdomen

3

What is the structure of the rectus sheaths that cover the abs? What is its relation to the inferior epigastric vessels?

1) Above arcuate line (upper 3/4) Rectus abdominis muscles - in anterior midline, covered by anterior and posterior rectus sheaths
anterior rectus sheath - external oblique aponeurosis and anterior lamina of interior oblique aponeurosis
posterior rectus sheath - posterior lamina of internal oblique aponeurosis and transverse abdominis aponeuorisis
2) Below arcuate line (lower 1/4)
internal oblique aponeurosis does not split at lateral border of abs
anterior sheath - all 3 aponeuroses pass anterior to rectus abdominis muscle
posterior sheath- there is none, muscle lies directly against transversalis fascia
3) Inferior epigastric vessels (branches of external iliac)
lie between posterior rectus sheath and abs, enter rectus sheath at arcuate line
below the line- lie between transversalis fascia and rectus abdominis
*anastamose with superior epigastric vessels (branches of internal thoracic vessels)

4

Define:
1) scrotum
2) inguinal ligament
3) flax inguinalis
4) conjoint tendon
5) cremaster muscle

1) scrotum - outpouching of skin and superficial fascia of the abdominal wall - has dartos fascia but no fatty layer
2) inguinal ligament- free edge of external oblique aponeurosis between ASIS and pubic tubercle where there is no bony attachment- folds under itself
lateral 2/3: internal oblique muscle attaches to folded under part of external oblique aponeurosis
medial 1/3: gap where spermatic cord/round uterus ligament pass through; b/w inguinal ligament and arching lower fibers of internal oblique muscle
3) falx inguinalis- arching lower fibers of internal oblique muscle, create a smaller gap through which spermatic cord passes through
4) conjoint tendon - fused tendons of internal oblique and transversus abdominis (continuation of falx inguinalis) *this is why 4 and 5 (internal ob and trans ab) are considered fused/combined entities in the scrotal area! attaches medially to linea alba, has free lateral border
5) cremaster muscle - evaginated skeletal muscle fibers of internal oblique (contracts to elevate spermatic cord/testis, innervated by genital branch of genitofemoral)

5

Explain the 3 mechanisms for thermoregulation of the testis

1) Contraction of the cremaster muscle will pull up the spermatic cord/testis towards abdomen to make warmer
how high you pull up the testis is determined by ambient temperature
cremateric clinical reflex- gently scratch inner upper thigh to cause cremaster to contract --> test L1 spinal cord segment integrity, works best in boys
2) smooth muscle of dartos fascia innervated by sympathetics --> pulls scrotum into tighter, smaller sac to decrease surface area and lose less heat
3) pampiniform venous plexus - continuation of testicular vein - surrounds testicular artery to bring heat from artery into veins and back to core --> facilitates countercurrent mechanism to lower testis temp

6

What is the inguinal canal? What are its walls?

Inguinal canal- pathway for descent of gonads
contains spermatic cord (male) round ligament of uterus (female)
begins at deep inguinal ring and ends at superficial inguinal ring
Walls:
anterior - external oblique aponeurosis (internal oblique/transversus abdominis in lateral half)
posterior - transversalis fascia (and internal oblique and conjoint tendon in medial half)
superior - arching fibers of falx inguinalis
inferior - inguinal ligament

7

Describe the descent of the testis through the inguinal canal and its coverings

1) Deep inguinal ring - evagination of the transversalis fascia (deep inguinal ring) --> internal spermatic fascia
2) passes under falx inguinalis through gap in inguinal ligament --> Cremasteric fascia (continuation of internal oblique aponeurosis)
3) passes through hole in the external oblique aponeurosis (superficial inguinal ring)--> external spermatic fascia
*has 3 coverings when leaving the superficial inguinal ring

8

What are the components of the spermatic cord?

ductus deferens
testicular artery
pampiniform plexus (testicular vein)
genital branch of genitofemoral nerve
autonomic nerves
lymphatic vessels

9

What are the mechanisms and positions of direct and indirect inguinal hernias.

How do you determine whether inguinal hernia is direct or indirect? (both in surgery and physical exam)

hernia- when something that should be contained comes out eg loops of bowl, extraperitoneal fat
1) indirect inguinal hernia - traverses inguinal canal, covered by same 3 fascial layers as testis
lateral to inferior epigastric artery and vein
2) direct inguinal hernia - does not follow preformed pathway, forms its own pathway and tears through walls; most likely to do this where canal is weakest --> superficial inguinal ring
-not covered by same fascial layers as testis, usually only the external spermatic fascia
-region they commonly go through is called Hasselbach's/inguinal triangle
-medial to inferior epigastric artery and vein
3)
A) during surgery- incise skin + superficial fascia
push hernia back in and palpate to feel for pulse of artery
if your finger is lateral to the artery --> indirect
if your finger is medial to the artery (can feel the pulse on lateral side) --> direct
B) during physical exam --> place examining finger on superficial ring and ask patient to cough (increase intrabdominal pressure to force hernia sac out) --> will hit your finger thus confirming inguinal hernia --> take another finger and compress wall over the deep ring and ask patient to cough second time --> if it doesn't push out against your finger --> your finger has stopped it --> is an indirect hernia

10

What is the difference between inguinal hernias and femoral hernias?
What is reducible vs incarcerated hernias

1) Inguinal hernias pass superficial to inguinal ligament (M>F, M have indirect > direct)
femoral hernias pass deep to inguinal ligament (F>M)
use pubic tubercle as bony landmark
*inguinal > femoral (75/25)
2) reducible - can be pushed back into abdomen
incarcerated - cannot be pushed back in
strangulated - blood supply compromised --> emergency
*femoral hernias at higher risk for incarceration /strangulation

11

Define:
1) processus vaginalis
2) tunica vaginalis

1) processus vaginalis is finger like evagination of parietal peritoneum which descends through inguinal canal, then testes follows
-cant have the pathway between peritoneum and scrotum open or you would have hernias all the time --> so processus fuses
-failure of fusion --> patent/persistent processus vaginalis, get congenital indirect inguinal hernias
-incomplete fusion --> hydrocele of spermatic cord (fluid-filled cyst)
2) distal unfused part of peritoneum, double layer - in direct contact with the testis

12

Describe the female inguinal regions and the similarities/differences with males - esp differences in gonad/ligament/artery etc

1) Similarities - mostly everything
-same 8 layers
-caudal genetic ligament - attaches from gonad to body of labioscrotal fold **inguinal canal and all the fascial layers form around the ligament
-gonad and caudal genetic ligament and gonadal artery descend into labioscrotal fold
2) Difference- what is coming through inguinal canal and where it goes
-round ligament of the uterus passes through
descends to skin of labium majus
-M: gonad = testis and ligament = gubernaculum and gonadal artery = in spermatic cord and labioscrotal fold = scrotum
F: gonad = ovary and ligament = round and ovarian ligaments and gonadal artery = in suspensory ligament and labioscrotal fold = labium majus

13

Describe the formation of the gut tube. What are the associated clinical problems that can occur?

1) formed in 3rd-4th weeks
dorsal part of endodermal yolk sac --> endoderm lined tube
buccopharyngeal and cloacal membranes rupture --> communication with oral and anal cavities
vitelline duct is communication bw gut tube and yolk sac, obliterates
2) Gastroschisis- weakness in abdominal wall when lateral body folds do not completely fuse--> intestinal contents in amniotic cavity, can penetrate out
-Vitelline fistula- failure of vitelline duct to close and obliterate, would see meconium/feces at umbilicus
-incomplete closure of vitelline duct: Ileal/Meckel's diverticulum (not in contact with outside cavity) or vitelline cyst, usually asymptomatic
-Atresia (failure of closure)- failure of gut tube to recanalize (epithelial plugs are vacuolized) --> leads to vomiting bc you cant empty the stomach, look for bile to see if obstruction is proximal or distal to the entry of the bile duct

14

What are the divisions of the gut tube, the organs they contain, and their neurovascular supply?

1) Pharynx
*celiac trunk, superior mesenteric artery, and inferior mesenteric artery are all branches of abdominal aorta
2) Foregut- celiac trunk (common hepatic, splenic, left gastric branches) + vagus X
esophagus
stomach
1st part and proximal 2nd part duodenum
also- liver, gall bladder, pancreas
3) Midgut- superior mesenteric artery (level of L1) + vagus X
rest of duodenum
jejunum, ileum, cecum
appendix
ascending colon
proximal 2/3 transverse colon
4) Hindgut- inferior mesenteric artery (level of L3) + sacral parasympathetic
distal 1/3 proximal colon
descending colon, sigmoid colon
rectum
upper part anal canal

15

What is the function of mesentaries? What are the dorsal and ventral mesentaries? What are their adult derivatives?

1) Carry neurovascular structures from retroperitoneal to peritoneal positions eg gut tube
2) Dorsal mesentary- bw gut tube and dorsal body wall (where abdominal aorta branches, along with N and V)
Ventral mesentary- bw gut tube and ventral body wall (only carries umbilical vein --> ligamentum teres/round ligament of liver)
3) Ventral mesentary: falciform ligament (bw liver and ventral body wall; contains ligamentum teres), lesser omentum (bw liver and stomach; contains bile duct, hepatic artery, portal vein)
*ventral mesentary disappears distally
Dorsal mesentary: greater omentum, splenorenal ligament, gastrosplenic ligament, etc

16

Describe the development of the liver

-location: 2nd portion of duodenum
-hepatic diverticulum - evagination of endoderm of gut tube --> marks end of foregut
proximal --> biliary duct system
distal end --> liver and gall bladder
-Ventral mesentary becomes:
lesser omentum- from liver to gut tube (contains bile duct)
visceral peritoneum of liver- part covering the liver
falciform ligament- from liver to ventral body wall

17

Describe the development of the pancreas. What clinical problem can occur?

1) location: 2nd part of duodenum
-2 pancreatic diverticuli evaginate from endoderm of gut tube
-ventral pancreatic bud rotates around the gut tube to dorsal mesentary to fuse with the dorsal pancreatic bud
-ventral bud: major pancreatic duct (empties with bile duct), lower head + uncinate process
dorsal bud: minor pancreatic duct (empties independently), upper head, neck, body, tail
2) Annular pancreas- ventral bud splits and rotates around both sides of gut tube --> can compress duodenum --> create GI obstruction --> vomiting

18

Describe the development of the spleen

Location: dorsal mesentary of the stomach (dorsal mesogastrium)
-mesoderm cells delaminate, migrate into layers between mesentary
-dorsal mesentary becomes:
splenorenal ligament- from dorsal body wall to spleen, contains splenic artery
visceral peritoneum of spleen- part covering spleen
gastrosplenic ligament- from spleen to gut tube
*not connected by a duct, not part of digestive system

19

What is the process of secondary retroperitonealization? What are examples?

1) Absence of ventral mesentary --> mobility of gut tube
visceral and parietal peritoneum fuse together --> become fusion fascia
organ becomes secondary retroperitoneal (partially covered by peritoneum)
secondary retroperitoneal organs are always in front of primary retroperitoneal organs, separated by fascia
2) secondary retroperitoneal
duodenum
pancreas
ascending colon
descending colon
upper rectum

20

Describe:
1) foregut rotation
2) midgut rotation + clinical abnormality

1) Foregut (stomach) rotates 90 degrees clockwise around long axis of gut tube
dorsal --> left (spleen) --> greater curvature/omentum
ventral --> right (liver) --> lesser curvature/omentum
lesser sac (posterior wall) --> epigastric pain
greater sac (anterior wall) --> hypogastric pain
space between two sacs --> Epiploic foramen of Winslow
2) Midgut rotates 270 degrees counterclockwise around superior mesenteric artery
jejunum --> left
cecum and ileum --> right
midgut moves into umbilical cord during gestation, retracts by week 12; failure of retraction --> omphalocele (loops of intestine in umbilical cord outside abdomen)

21

Compare/contrast omphalocele and gastroschisis

Similarities:
-both have intestines outside abdomen when they should be inside
Differences:
-omphalocele is GI due to failure of intestines to retract in week 12, they are inside umbilical cord
-gastroschisis is failure of fusion leading to body wall defect in week 4; intestines outside umbilical cord
-mortality higher with omphalocele due to associated cardiac and kidney defects

22

What are the subdivisions of the abdominal cavity and what organs do they contain?

Greater peritoneal sac - both supracolic and infracolic
-supracolic - stomach, liver, spleen
-boundary - fused greater omentum + transverse mesocolon
-infracolic - small intestine, ascending colon, descending colon
Omental bursa (lesser sac)- posterior to stomach and lesser omentum and gastrocolic ligament (part of greater omentum thats not fused *surgical entry point for posterior wall of the stomach)

23

Describe the portal venous systes incl the points of anatastamosis and potential clinical abnormalities

portal vein drains peritoneal and secondary retroperitoneal organs
IVC drains primary retroperitoneal organs
flow: splenic/superior mesenteric/inferior mesenteric veins --> hepatic portal vein --> sinusoids in liver --> hepatic veins --> IVC --> heart *no valves in portal system
Anastamoses:
1) Left gastric (portal) Azygos (caval)
Esophageal varices: dilated veins bulge into wall of esophagus --> vomit blood
2) Paraumbilical (portal) epigastric (caval)
Caput medussae: dilated veins in superficial fascia, see them radiating away from umbilicus
3) Superior rectal (portal) inferior and middle rectal (caval)
Internal hemorrhoids: dilating bulging veins in lumen of rectum (no pain bc no nociceptors)
*clinical abnormalities suggest portal hypertension (veins dilate when you utilize anastamosis)

24

What is the lymphatic drainage in relation to the vasculature of the gut?

lymphatic pathways follow vasculature with nodes interspersed
lymphatic channel --> intestinal lymphatic trunks --> cysterna chyli --> thoracic duct

25

What are the 3 major openings in diaphragm for entrance into abdomen?

What are the types of hiatus hernias?

1) Caval hiatus - how IVC crosses
2) Esophageal hiatus - esophagus passes through right crura skeletal muscle at T10, acts as sphincter to control passage of food
3) Aortic hiatus

1) Sliding: esophagus, cardia (opening of stomach), and part of fundus slide upwards into thorax --> regurgitation problems
Paraesophageal: cardia and esophagus in normal position but fundus moves up into thorax --> no regurgitation

26

What is the anatomy and arterial supply of the stomach?

peritoneal organ
3 layers of smooth muscle: outer longitudinal, middle circular (pyloric sphincter to control passage of food into duodenum), inner oblique
arterial supply:
right gastroomental left gastroomental
right gastric left gastric
short gastric aa (poor intraceliac anastamoses)

27

What is the anatomy and arterial supply of the duodenum?

starts at pylorus, C-shaped course around head of pancreas
part 1 is peritoneal, parts 2-4 are secondary retroperitoneal
arterial supply:
gastroduodenal --> anterior + posterior superior pancreaticoduodenal
superior mesenteric --> anterior + posterior inferior pancreaticoduodenal (traverses head of pancreas to get to the duodenum)

28

What is the anatomy and arterial supply of the pancreas?

Head, uncinate process (From ventral bud, empties into major duct along with common bile duct)
neck, body, tail (from dorsal bud, empties into minor duct)
arterial supply:
pancreaticoduodenal arcades (collateral circulation bw celiac trunk and SMA) --> head and neck
splenic artery --> body and tail

29

What is the anatomy and arterial supply of the liver + gallblader?

liver has 2 lobes--> left lobe: left, caudate, quadrate lobes
+ right lobe
portal triad: portal vein, proper hepatic artery, common hepatic duct
cystic artery supplies gall bladder (in triangle of Calot bounded by liver, cystic duct, and common hepatic duct)

30

Describe the flow of the biliary duct system

R and L hepatic ducts --> common hepatic duct + cystic duct (From gallblader) --> common bile duct --> hepatopancreatic ampulla of Vater --> duodenum

31

What is the anatomy and arterial supply of the spleen?

*technically not part of GI tract
attaches in front of left kidney under ribs 9-11
attached to stomach through gastrosplenic artery
attached to posterior body wall by splenorenal ligament (blood supply through here)
arterial supply: splenic artery

32

What are the anatomical differences between jejunum and ileum?

jejunum- first 40% and on upper left, ileum 60% and lower right
jejunum compared to ileum:
> vascularity
longer vasa recta
arcades are a few large loops
less fat in mesentary
longer
deeper red because more vascular
thicker/heavier wall
large tall and closely packed circular folds --> more feathery appearance on barium contrast
fewer lymphoid nodules

33

What is the anatomy and arterial supply of the large intestine ie colon?

tianiae coli -- 3 strips of longitudinal smooth muscle, meet at appendix
omental appendices- pockets of fat bw peritoneum and wall
haustra- small pouches/sacs (give segmented appearance)
arterial supply:
ascending colon: ileocolic and right colic arteries
transverse colon: middle colic
descending colon: left colic
sigmoid colon: sigmoid arteries

34

What are the arterial anastamoses in the GI tract?

Celiac trunk (foregut) pancreaticoduodenal arcades Superior mesenteric artery (midgut)
Superior mesenteric artery marginal artery of Drummond Inferior mesenteric artery
Inferior mesenteric artery Superior rectal artery Middle rectal and inferior rectal (via internal pudendal) arteries Internal iliac artery

35

What is the sympathetic innervation for the abdominal GI tract?

function: vasoconstriction, decrease motility and secretion
preganglionics in lateral horn of T5-L2, leave paravertebral ganglion and run in splanchnic nerve to synapse in prevertebral ganglion, then travel on arteries

36

What is the parasympathetic innervation for the abdominal GI tract?

function: increase motility and secretion
preganglionics in brainstem or sacral spinal cord, travel along vagus or pelvic splanchnic to synapse on terminal ganglia studded along the walls of the organs of the GI tract

37

Describe the enteric nervous system

neurons found along the walls of the GI tract
function: intrinsic control of motility and secretion
-myenteric plexus - bw longitudinal and circular muscles; sympathetic innervation --> contraction of muscle tone, parasymp --> increased peristalsis
-submucosal plexus - in submucosal layer; symp --> fluid transport, parasymp--> stimulates secretomotor function

38

Describe the different stages of abdominal pain

1) Visceral - dull, poorly localized, midline
-site of pain is from dermatomes where diseased organ receives motor innervation
-epigastric T6/T7 (foregut pain), umbilical T10 (midgut pain), suprapublic L1 (hindgut pain)
2) Referred - experience pain at the dermatomes of the somatic nerves that arise from the same part of the spinal cord as the sensory nerves
-well localized, lateralized (on one side)
-eg loin to groin for ureteric calculi/stones, back pain for retroperitoneal (kidneys, pancreas), ovaries to T10/T11
3) Parietal- interaction with diseased organ and parietal peritoneum
-more intense, more precisely localized
-carried in somatic afferent sensory nerves

39

Describe the development of the fetal and adult kidneys as well as ureter. What is the associated clinical abnormality?

Intermediate mesoderm --> urogenital ridge:
nephrogenic ridge (lateral part) --> embryonic kidney
metanephrogenic blastema (caudal part) --> adult kidney
gonadal ridge (medial) --> gonads
1) 4th week: pronephros differentiate and then degenerate in cranio-caudal direction
2) form mesonephros - kidney until week 10
makes urine which goes through mesonephric tubules --> the mesonephric duct --> cloaca or urogenital sinus (after cloaca ruptures week 7) --> amniotic cavity
3) ureteric bud forms - evagination from mesonephric duct that invades metanephrogenic blastema and induces it to become nephrons (filtration part)
unbranched part of ureteric bud --> ureter
4) metanephrogenic blastema induces ureteric bud to branch: renal pelvis --> major calyces --> minor calyces --> renal pyramid (apex is renal papilla, contains collecting tubules (conducting part)

Renal agenesis (missing kidneys) - failure of ureteric bud to reach metanophrogenic blastema --> can lead to oligohydramnios --> Potter sequence

40

Describe the ascent of the kidneys and associated clinical abnormalities

1) Kidneys develop in pelvis (metanephrogenic blastema at sacral spinal levels) around week 5
ascent: differential growth - appear to ascend to lumbar levels by week 9, gain new arteries and lose lower arteries
rotation: hilum of kidney (where vessels leave) is initially anterior --> medial
2) pelvic kidney if it doesn't rise
horseshoe kidneys if they fuse, cant rise higher bc of inferior mesentary artery branching off aorta

41

Describe oligohydramnios and polyhydramnios

1) Oligohydramnios - reduced volume of amniotic fluid which is mostly urine (failure to produce normal volume or renal agenesis or failure of uteric buds to form)
leads to Potter sequence --> hypoplastic (underdeveloped) lungs, limbs, and face
2) Polyhydramnios - increased volume of amniotic fluid problems with urinary tract absorption by small intestine or swallowing eg anencephaly

42

Describe development of urethra and bladder and associated clinical abnormalities

1) urorectal septum grows downwards --> divides cloaca (caudal part of the gut tube) by week 7 --> urogenital sinus + anorectal canal
bladder -- upper portion of urogenital sinus, incorporates the mesonephric ducts
urethra -- caudal portion of urogenital sinus

2) Failure of fusion of the allantois into the urachus/median umbilical ligament
no fusion --> fistula (urine at umbilicus)
incomplete fusion --> one-sided sinus
opening in middle --> cyst

43

What is the relationship of the renal artery, vein, and pelvis at the hilum?

Hilum- where vessels enter/exit at organ; at medial surface of kidney
renal vein is most anterior (left renal vein longer, crosses aorta to drain into IVC; in SMA syndrome - supply to left kidney, left adrenal gland, and left gonad compromised)
renal artery is in the middle behind the vein (--> segmental end arteries --> interlobar --> arcuate arteries --> interlobular end arteries)
renal pelvis is most posterior, leads downwards and narrows into the ureter

44

What is the course, blood supply, and innervation for the ureter? Where are the 3 locations for kidney stones to get lodged?

1) Course: leaves kidney anterior to psoas major, descends in retroperitoneal space, crosses pelvic brim anterior and imm distal to bifurcation of the common iliac artery, passes obliquely through bladder wall
2) Blood supply: renal --> aorta --> common iliac; cant retain all for kidney transplant so upper portion ureter + renal artery supply + kidney transplanted close to bladder
3) Innervation: parasympathetic (vagus + pelvic splanchnic), sympathetic (T10-L2 from lesser + least + lumbar splanchnics), sensory (T10-L2); pain is loin --> groin (Referred pain)
4) 1st=ureteropelvic junction (at renal pelvis at junction of kidney and ureter), 2nd=crossing pelvic brim, 3rd=ureterovesical junction (junction of ureter and bladder); obstruction results in colic (painful muscle contraction)

45

Describe the anatomy and innervation of the bladder

bladder is extraperitoneal but can ascend as it fills
detrusor smooth muscle (parasympathetic sacral spinal cord S2-4, - pelvic splanchnic nerves)- when it contracts, bladder expels urine + also compresses ureter to prevent retrograde flow of urine
internal urethral sphincter (sympathetic lumbar spinal cord)- also smooth muscle; when it contracts, retain urine in bladder
trigone at opening of urethra - from mesoderm, but then overgrown so all bladder = endodermally derived
blood supply: internal iliac arteries
venous drainage: internal iliac vein
lymphatic drainage: external and internal iliac nodes

46

What is the basis for sex differentiation?

Embryo preprogrammed to be female, becomes male with Y chromosome
SRY region --> TDF --> gonadal ridge becomes testis --> leydig cells produce testosterone (male genital system develops) + sertoli cells produce MIF (inhibits development of female genital tract)
absence of factors --> ovary and female genital system develop

47

Describe the process of gonad formation

4th week: Primordial germ cells from the wall of the yolk sac travel through dorsal mesentary to hindgut
6th week: Enter gonadal portion of urogenital ridge
induce ridge to develop into gonad
germ cells become gametes

48

Describe what male genital system is devlpd from

Mesoderm:
gonadal ridge --> testis
mesonephric tubules --> efferent ductules
mesonephric duct --> ductus deferens + epididymis + seminal vesicles + ejaculatory duct
Endoderm:
urethra
prostate
bulbourethral glands
Ectoderm:
glandular plate (distale end of penis)
*prostatic utricles if the paramesonephric ducts do not fuse on midline prior to fusion with urogenital sinus

49

Describe what female genital system is devlpd from

mesonephric duct degenerates
paramesonephric duct located laterally - coelom invagination on surface of urogenital ridge (THIS is why uterine tube opens into peritoneal cavity)
Mesoderm:
gonadal ridge --> ovary
paramesonephric ducts fuse at midline to become uterus, unfused portion is uterine tubes
caudal end of fused ducts --> cervix, upper 1/3 vagina
fused paramesonephric ducts come in contact with
remnant of vaginal plate --> hymen
Endoderm:
sinus tubercules --> lower 2/3 of vagina
urogenital sinus --> vestibule (common cavity where urethra and vagina open)
*no ectoderm in female reproductive

50

Describe the devlpt of external genitalia in males and females

Weeks 3+4: proliferation of mesenchyme --> genital tubercle, cloacal folds which become urethral and anal folds, and labioscrotal folds
Males:
genital tubercle --> penis
urethral folds --> ventral midline penis
labioscrotal folds --> scrotum
glandular plate grows back, canalizes --> distal end of penile urethra
Females:
genital tubercle --> clitoris
urethral folds --> labia minora
labioscrotal fold --> labia majora

51

Define the true pelvis, false pelvis, and perineum.
Distinguish between the anatomy of the male and female pelvis

1) true pelvis - below pelvic brim, pelvic outlet is between ischiopubic rami
false pelvis - above pelvic brim in abdominal cavity to iliac crest
perineum- below pelvic floor (between thighs) - where external genitalia is located
greater sciatic foramen - connects gluteal region to true pelvis
lesser sciatic foramen - connects gluteal region with perineum
obturator canal - connects pelvis to medial thigh
2)
Male - pelvis is more narrow and deep, thick and heavy, smaller infrapubic angle
Female - pelvis is more wide and shallow, thing and light, large infrapubic angle of outlet

52

Describe the importance of the pelvic floor (/diaphragm) and the structures passing through pelvic floor musculature

1) Importance - supports pelvic viscera; sphincteric control over pelvic visceral functions; separates true pelvis from perineum; contracts with increased intrabdominal pressure (pressure on abdominal viscera extends to pelvic viscera)
2) composed of obturator internus and levator ani - 3 muscles (puborectalis muscle is sling for rectum)
tendinous arch/muscular white line - thickening of the obturator internus fascia where the pelvic floor attaches
supports effluent tubes - urethra + vagina through urogenital hiatus, and anal canal that pass through pelvic floor (otherwise go out through greater sciatic and back in through lesser sciatic foramen)
skeletal muscle innervated by ventral rami of S4

53

Describe the endopelvic fascia and subsets responsible for supporting pelvic viscera

1) Importance - provides static support to pelvic viscera; covers pelvic walls, floor, viscera
2) composed of connective tissue and smooth muscle
connected to fascial white line (thickening of levator ani fascia bw pubis and ischial spine)
Attachment of 2 ligaments and 2 fascial sheets
-transverse cervical (/cardinal) ligament
-uterosacral ligament
-anterior pubocervical fascial sheet (bw bladder and uterus, supports anterior vaginal wall)
-posterior rectovaginal fascial sheet (bw uterus and rectum, supports posterior vaginal wall)

54

Describe clinical manifestations of loss of pelvic support

1) cystocele - bladder pushing into anterior vaginal wall; damage to pubocervical fascia (can be pushed up)
2) rectocele - rectum pushes through vaginal wall; caused by damage to rectovaginal fascia (can be pushed down)
3) Stress urinary incontinence - torn pubocervical fascia so that when there is increased abdominal pressure (coughing, sneezing), urethra moves posteriorly and is not closed by the fascia-- allowing leakage

55

Describe anatomy, functions, and blood supply of female pelvic viscera:
1) bladder
2) vagina
3) uterus
4) uterine tubes
5) ovaries
6) Rectum

1) Bladder- consists of detrusor smooth muscle, function is to store urine; ureter enters bladder neck at trigone (Triangular region) - acts like a valve; urge to urinate when the bladder fills and walls stretch; opens inferiorly into the vestibule
2) Vagina - 10 cm tube oriented superoposteriorly; cervix at superior end, opens inferiorly into the vestibule
blood supply: internal iliac, internal pudendal
innervation: pelvic vagina (uterovaginal plexus, pain via pelvic splanchnics), perineal vagina (somatics and pain via pudendal)
3) Uterus - uterine tubes enter bw fundus and body; anteverted (cervix entering vagina) and anteflexed (body tipped forward, rests on bladder); 3 layers: peri, myo, and endometrium
blood supply: uterine (anterior branch internal iliac), vaginal, umbilical
innervation: sympathetics above pelvic pain line, pelvic splanchnics below pelvic pain line
4) Uterine tubes - passageway for eggs to reach uterus; infundibulum= opening into peritoneal cavity, fimbrae= fingers on the ends
5) Ovaries - female gonads; IP/suspensory ligament (contains ovarian vessels) and proper ovarian ligament
Innervation: referred pain at T10/T11
6) Rectum - smooth layer (not ruffled like sigmoid colon), starts at S3; fecal matter stored in inferior ampulla
blood supply- superior rectal (inferior mesenteric), middle (internal iliac branch) and inferior rectal (internal pudendal branch)
innervation: parasympathetics pelvic splanchnic (peristalsis)

56

Describe anatomy, functions, and blood supply of male pelvic viscera:
1) bladder
2) prostate
3) ampulla of vas deferens
4) seminal vesicle

1) Bladder- Bladder- consists of detrusor smooth muscle, function is to store urine; ureter enters bladder neck at trigone (Triangular region) - acts like a valve; urge to urinate when the bladder fills and walls stretch
2) Prostate - between neck of bladder and urogenital hiatus; consists of stroma (collagen + smooth muscle) and epithelial glandular cells (secrete prostatic fluid); prostatic sinus and ejaculatory ducts (seminal fluid + sperm) open here; prostate gets larger in men over time (harder to urinate) --> benign prostatic hyperplasia
80% prostate cancers in peripheral zone
blood supply: inferior vesicle artery (internal iliac), prostatic venous plexus
innervation: (parasympathetics) - secretomotor/erection; (Sympathetic) - smooth muscle contraction during ejaculation
3) Ampulla of ductus deferens - emlarged portion before it reaches prostate, where sperm is stored prior to ejaculation
4) Seminal vesicle - lateral to the ampulla, provide seminal fluid (fructose), forms ejaculatory duct with ampulla which opens into prostatic urethra

57

Describe the lymphatic drainage of pelvic visceral structures and the pathways metastatic
disease may follow

lymph nodes follow arteries
ovarian cancer spreads to lateral aortic nodes (since ovaries started in posterior abdominal wall and then descended)
cervical cancer spreads to internal iliac nodes (following internal iliac arterial path)

58

Outline both sympathetic and parasympathetic pathways involved in motor innervation of pelvic viscera

1) Sympathetic - vasoconstriction of pelvic arteries, contraction of smooth muscle sphincters (urethral and anal), peristalsis of male reproductive tract
Preganglionic bodies - lateral horn of L1, L2
Postganglionic bodies - inferior hypogastric plexus (pregang travel on superior hypogastric plexus, goes directly to organ after synapsing); superior mesenteric, or inferior mesenteric plexuses (travel on blood vessels)

2) Parasympathetic - inhibits smooth muscle sphincters, contraction of smooth muscle of bladder and rectum
Preganglionic bodies - S2,3,4 cord segments --> pelvic splanchnic nerves
Postganglionic bodies - inferior hypogastric plexus, or ganglia in walls of viscera (travel on internal iliac artery branches)

59

Describe the pathways of pelvic visceral pain including where that pain is perceived on the body

Parasympathetics carry reflex afferents
Pelvic pain line:
Above line- peritoneal structures eg body of uterus, tubes, ovaries --> sympathetic fibers to T10/L1 --> lower back pain
Below line - subperitoneal structures eg cervix, bladder --> parasympathetic pelvic splanchnic nerves to S2,3,4 --> perineal region/lower limb pain

60

Identify the major autonomic nerves responsible for innervating pelvic viscera

1) Superior hypogastric plexus: pre and postganglionic sympathetics, visceral afferents
2) Hypogastric nerves (R/L): Pre and postganglionic sympathetics, visceral efferents
3) Inferior hypogastric plexus: pre and postganglionic sympathetics, pre and postganglionic parasympathetics (postgang cell bodies here for synapsing), visceral afferents
4) Pelvic splanchnic: preganglionic parasympathetics, visceral afferents

61

Define perineum and describe its organization into two triangles

Perineum - diamond shaped region between the thighs, containing anal canal + external genitalia
I. Anal triangle: anal canal + ischioanal fossa
II. Urogenital triangle: urethra and external genitalia contained within deep and superficial perineal pouches

62

Anal triangle of perineum
1) Describe the anal canal and its blood supply/innervation
2) Describe anatomy of the ischioanal fossa incl clinical significance of anterior recess

1) Anal canal with internal sphincter (involuntary smooth, tonically contracted) and external sphincter (voluntary skeletal somatic)
-above pectinate line - hindgut (endoderm)
innervation: motor (autonomic - symp + parasymp) + sensory (visceral afferent, pressure)
blood supply: arterial (superior rectal), venous (superior rectal --> hepatic portal venous)
lymphatic: internal iliac
hemorrhoids: internal (painless)
-below pectinate line - proctodeum (ectoderm)
innervation: motor (somatic efferent to external anal sphincter) + sensory (somatic efferent, pain, temp, touch)
blood supply: arterial (inferior rectal), venous (inferior retal --> caval venous system)
lymphatic: superficial inguinal nodes
hemorrhoids: External (painful)
2) Ischioanal fossa - triangle fat filled space that allow for distension and contraction of the anal canal; muscles include pelvic floor/diaphragm and obturator internus
inferior rectal branches of NAV pass through here
pudendal canal with NAV runs on lateral wall, medial to obturator internus
anterior recess is reflection of fossa with UG diaphragm - abscess fluid can enter, would be above UG diaphragm and below pelvic diaphragm

63

Describe the anatomy of the male and female superficial perineal pouches including the major fascial relationships, which extend to the anterior abdominal wall

roof is perineal membrane, floor is superficial perineal fascia
1) Anatomy
1st layer- attach erectile bodies to UG diaphragm and ischiopubic rami
2nd layer - cover erectile bodies with deep fascia (acts as tourniquet to maintain erection)
3rd layer - skeletal muscle attached to perineal body
4th layer - superficial perineal fascia
5th layer- skin

2) Contents
both M and F have Bulbospongiosus (ejaculation/feelings of orgasm), Ischiocavernosus (maintains erection), Superficial Transverse Perineal muscles, and spongy urethra
Male: bulb of penis (erectile tissue), corpus spongiosum (erectile tissue, contains urethra, forms glans penis), R/L crura of the penis, corpora cavernosa (erectile tissue, primarily engorges with blood during erection)
Female: vestibular bulb (erectile tissue), greater vestibular gland (Bartholin's gland, for lubrication), vagina (splits 2 pouches, not really in the pouch), R/L crura of the clitoris

3) Fascia
Male: Buck's fascia (deep penile)
Colles' fascia (superficial perineal fascial floor)
Scarpa's (anterolateral abdominal wall) -- superficial penile (penis) -- Dartos (scrotum)
*urethral tears possible with Buck's fascia tear, blood and urine in superficial pouch and abdomen

64

What is the urogenital diaphragm and its anatomy
What are the contents of the deep perineal pouch in males and females

1) Below the pelvic floor/diaphragm
-covers the urogenital hiatus
-base of support for external genitalia
-contains deep perineal pouch (roof is superior fascia, floor is perineal membrane)
-sphincteric control of urethra and vagina
2)
-superior fascia from ramus to ramus - covers UG hiatus
-muscles attached
-inferior fascia (perineal membrane) from ramus to ramus
3) Males: sphincter urethrae m, deep transverse perineal m, bulbourethral glands (for lubrication, homologous to vestibular glands in F which are in superficial perineal pouch), NAV, membranous urethra
Females: sphincter urethrae m (*blends with other muscle fibers so less effective), deep transverse perineal m, vagina, NAV, membranous urethra

65

What is the perineal body?

Central tendon area - support structure where muscles attach
attachments:
-external anal sphincter
-external urethral sphinter
-bulbospongiosus m + superficial transverse perineal m
-deep transverse perineal m
-anterior fibers, levator ani muscle
located between urogenital triangle and anal triangle
adult remnant of urorectal septum which came down and divided UG sinus and rectal canal
abnormalities: can get rectocele or uterine prolapse if the perineal body tears

66

What is the blood supply in the perineum?

Blood: branches of internal pudendal (from internal iliac artery); exits pelvis via greater sciatic foramen, runs along the ischial spine in the gluteal region, then enters ischioanal fossa of anal triangle through lesser sciatic foramen, runs in pudendal canal to reach urogenital triangle; supplies pouches, anal canal, and erectile tissue
Venous: Deep dorsal vein of penis or clitoris, drains in prostatic venous plexus and vesicle venous plexus, respectively

67

What is the somatic and autonomic innervation of the perineum?

1) Somatic: pudendal nerves (both motor and sensory)
inferior rectal - motor to external anal sphinctor + levator ani, sensory to skin of anal triangle
dorsal nerve - sensory to dorsum of penis/clitoris
perineal - motor and sensory to everything in deep and superficial pouches
2) Sympathetic - vasoconstriction
preganglionic cell bodies in L1, 2
1st pathway: lumbar splanchnic --> superior hypogastric plexus --> hypogastric nerves --> synapse at inferior hypogastric plexus (travel on internal pudendal artery)
2nd pathway: travel down sympathetic chain, synapse at sacral paravertebral ganglia S2, 3, 4 (travel in pudendal nerves)
3) Parasympathetic - vasodilation arteries in erectile tissues to stimulate erection
preganglionic bodies in S2, 3, 4
pelvic splanchnic nerves --> synapse at inferior hypogastric plexus (Travel in cavernous nerves)