Gastrointestinal - Embryo & Anatomy

sefomepu's version from 2015-06-18 14:18


Question Answer
Gastroschisisextrusion of abdominal contents, not covered
Omphaloceleextrusion of abdominal contents, covered by peritoneum
Failure of rostral fold closuresternal defects
Failure of lateral fold closureomphalocele, gastroschisis
Failure of caudal fold closurebladder exstrophy
Duodenal atresia (failure to recanalize)Trisomy 21
Jejunal, ileal, colonic atresiad/t vascular accident (apple peel atresia)
Esophageal atresia with distal tracheoesophageal fistulamost common cause of EA (85%)
Drooling, choking, vomiting with first feeding
TEF allows air into the stomach → visible on CXR
failure to pass NG tube into stomach
H-type esophageal atresiaPure TEF
Pure EA does not show...gas in abdomen on CXR
Pyloric stenosispalpable "olive" mass in epigastric region
nonbilious projectile vomiting at ~2 weeks of age
Tx: surgical incision
often firstborn males
Pancreas derived fromforegut
Ventral pancreatic bud →pancreatic head, main pancreatic duct, uncinate process
Dorsal pancreatic bud →body, tail, isthmus, accessory pancreatic duct
Annular pancreasventral pancreatic bud abnormally encircles 2nd part of duodenum
forms a ring of pancreatic tissue that may cause duodenal narrowing
Pancreas divisumventral and dorsal parts fail to fuse at 8 weeks
Spleen arises from where?mesentary of stomach
BUT it's supplied by the foregut (celiac artery)
Retroperitoneal structures (mnemonic)SAD PUCKER
Suprarenal gland (adrenal)
Aorta and IVC
Duodenum (2nd and 3rd parts only)
Pancreas (except tail)
Colon (descending and ascending only)
Esophagus (thoracic portion)
Rectum (lower 2/3rds)

GI Ligaments

Question Answer
Falciform connectsliver to anterior abdominal wall
Gastrohepatic connectsliver to lesser curvature of stomach
Gastrocolic connectsgreater curvature and transverse colon
Gastrosplenic connectsgreater curvature and spleen
Splenorenal connectsSpleen to posterior abdominal wall
Falciform containsligamentum teres hepatis
(derivative of fetal umbilical vein)
Hepatoduodenal containsPortal triad: hepatic artery, portal vein, common bile duct
Gastrohepatic containsgastric arteries
Gastrocolic containsgastroepiploic arteries
Gastrosplenic containsshort gastrics, left gastroepiploic vessels
Splenorenal containsSplenic artery and vein, tail of pancreas
Falciform is derived from...ventral mesentery
Pringle maneuverhepatoduodenal ligament may be compressed between thumb and index finger to control bleeding
Which ligaments connect the greater and lesser sacs?Gastrohepatic - on the right
Gastrosplenic - on the left
Which ligament is part of the greater omentum?Gastrocolic

Digestive tract

Question Answer
Layers of gut wall, from inside → outMSMS
Muscularis externa
Serosa/adventitia (when retroperitoneal)
Mucosal layer contains which layers?epithelium - absorption
lamina propria - support
muscularis mucosa - motility
Which layer contains Meissner's plexus?Submucosa, (submucosal nerve plexus)
Which layer contains Auerbach's plexus?Muscularis externa, (myenteric nerve plexus)
Fn of myenteric plexus?controls muscle contractions
Fn of submucosal plexus?controls secretory activity
Definition of ulcer vs erosionUlcer - extends into submucosa
Erosion - stays in mucosa only
Frequency of stomach rhythm3 waves/min
Frequency of duodenal rhythm12 waves/min
Frequency of ilium rhtyhm8-9 waves/min
Histology of esophagusnonkeratinized stratified squamous epithelium
Histology of stomachgastric glands
Histology of DuodenumVilli and microvilli (↑ absorptive surface)
Brunner's glands (submucosa)
crypts of Lieberkuhn
Histology of jejunumPlicae circulares and crypts of Lieberkuhn
Histology of ileumPeyer's patches (lamina propria, submucosa)
plicae circulares (proximal ileum)
crypts of Lieberkuhn
Largest # of goblet cells in the small in the small intestine
Histology of coloncrypts but no villi
numerous goblet cells
Foregut blood supply/parasymp innervation/vertebral levelceliac trunk
Midgut blood supply/parasymp innervation/vertebral levelSMA
Hindgut blood supply/parasymp innervation/vertebral levelIMA

Blood supply

Question Answer
Structures supplied by celiac trunkStomach to proximal duodenum
Structures supplied by SMADistal duodenum to proximal 2/3 of transverse colon
Structures supplied by IMADistal 1/3 of transverse colon to upper portion of rectum
splenic flexure is a watershed region
Branches of celiac trunkcommon hepatic, splenic, left gastric → main blood supply of the stomach
Stong anastomoses of circulation around stomachleft and right gastroepiploics
left and right gastrics
Poor anastomoses around stomachshort gastrics (if splenic artery is blocked)
4 arterial anastomoses compensate if branches off the abdominal aorta are blocked1. superior epigastric (internal thoracic/mammary) ↔ inferior epigastric (external iliac)
2. Superior pancreaticoduodenal (celiac trunk) ↔ inf. pancreaticoduodenal (SMA)
3. Middle colic (SMA) ↔ left colic (IMA)
4. Superior rectal (IMA) ↔ middle and inferior rectal (internal iliac)
5 portosystemic anastomosesesophagus: left gastric ↔ esophageal
below umbilicus: paraumbilical ↔ sup/inf epigastrics
above umbilicus: paraumbilical ↔ superior epigastric/lateral thoracic
rectum: superior rectal ↔ middle and inferior rectal
Theraputic/artificial: portal vein ↔ hepatic vein - relieves portal hypertension by shunting blood to systemic circulation
Clinical signs of portal hypertension (realization of shunts)Esophageal varices
Caput medusae
Internal hemorrhoids
Blood supply/drainage above pectinate lineA: superior rectal artery (IMA)
V: superior rectal vein → inferior mesenteric vein → portal system
Blood supply/drainage below pectinate lineA: inf rectal artery (branch of internal pudendal artery)
V: inf rectal vein → internal pudendal vein → internal iliac vein → IVC
Cancers, hemorrhoids, and pectinate linesAbove pectinate line: internal hemorrhoids (not painful), adenocarcinoma
Below pectinate line: external hemorrhoids (painful, innervated by inf. rectal branch of pudendal n.), squamous cell carcinoma
Lymphatic drainage above/below pectinate linesAbove: deep nodes
Below: superficial inguinal nodes

Liver/biliary system

Question Answer
Zone 1 of liverperiportal zone
affected 1st by viral hepatitis
Zone 2 of liverintermediate zone
Zone 3 of liverpericentral vein (centrilobular) zone:
-affected 1st by ischemia
-contains P450 system
-most sensitive to toxic injury
-site of alcoholic hepatitis
Apical surface of hepatocytes faces what?bile canaliculi
Basolateral surface of hepatocytes faces what?sinusoids
Flow of blood through liverZone 1 → Zone 3
Flow of bile through liverZone 3 → Zone 1
Portal triadBile duct, branch of portal vein, branch of hepatic artery
Space of Disselymphatic drainage
Ampulla of Vaterwhere main pancreatic duct and common bile duct both drain into duodenum
Sphincter of Oddicontrols bile/pancreatic juice flow out of the ampulla of Vater
Relationship of cystic duct, common bile duct, and common hepatic ductcystic duct + common hepatic duct = common bile duct

Femoral/inguinal region

Question Answer
Organization of structures at femoral triangleLateral→Medial
NAVEL: nerve, artery, vein, empty space, lymphatics
Femoral sheathcontains femoral vein, artery, and deep inguinal lymph nodes - NOT the femoral n.
Located 3-4 cm below the inguinal ligament
Direct herniathrough abdominal wall (parietal peritoneum, extraperitoneal tissue, transversalis fascia, covered by external spermatic fascia) through Hesselbach's triangle (external/superficial inguinal ring):
- medial to inf. epicastric artery
- lateral to rectus abdominus m
- superior to inguinal ligament
Order of muscles from deep to superficialRectus abdominis, pyramidalis, transversus abdominis, internal oblique, aponeurosis of external oblique muscle
Indirect herniaprotrusion through internal inguinal ring, external (superficial) inguinal ring, scrotum
enters internal inguinal ring lateral to inf epigastric a.
Femoral herniaProtrudes below inguinal ligament through femoral canal below and lateral to pubic tubercle
More common in women
Leading cause of bowel incarceration
Diaphragmatic herniaMost commonly a hiatal hernia: stomach herniates upwards through esophageal hiatus of the diaphragm
Sliding hiatal herniaMC hiatal hernia (diaphragmatic hernia)
GE junction is displaced superiorly - "hourglass stomach"
Paraesophageal herniaHiatal hernia (diaphragmatic hernia)
GE junction is normal.
Fundus protrudes into the thorax