S&F Part III Flashcards
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
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
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)
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)
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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)
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
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)
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)
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
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
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)
