GI, USMLE Flashcards
Derivatives of foregut
Pharynx to duodenum
Derivatives of midgut
Duodenum to proximal 2/3 of transverse colon
Derivatives of hindgut
Distal 1/3 of transverse colon to rectum
Developmental defects: Failure of rostral fold closure
Sternal defects
Developmental defects: Failure of lateral wall closure
1) Omphalocele 2) Gastroschisis
Developmental defects: Failure of caudal fold closure
Bladder extrophy
Developmental defects: Failure to recanalize
Duodenal atresia
Developmental defects: Duodenal atresia is seen in what genetic disorder
Trisomy 21
Developmental defects: Due to vascular accident
Jejunal, ileal, and colonic atresia
Developmental defects: Jejunal, ileal, and colic atresia is aka
Apple peel atresia
Midgut development: Herniates through umbilical ring at
6th week
Midgut development: Returns to abdominal cavity and rotates around SMA at
10th week
Developmental defect: Extrusion of abdominal contents through abdominal folds, not covered by peritoneum
Gastroschisis
Developmental defect: Persistence of herniation of abdominal contents into umbilical cord, covered by peritoneum
Omphalocele
Gastroschisis: Constant size
Less than or equal to 5cm
Derivatives of midgut
Duodenum to transverse colon
Tracheoesophageal anomalies: Most common
EA with distal TEF
Gastroschisis: Constant location
Right of the umbilical cord
Retroperitoneal structures
SAD PUCKER 1) Suprarenal gland 2) Aorta and IVC 3) Duodenum (2nd, 3rd, and 4th parts) 4) Pancreas (except tail) 5) Ureters 6) Colon (ascending and descending) 7) Kidneys 8) Esophagus (lower 2/3) 9) Rectum (upper 2/3)
Pentalogy of Cantrell
1) Epigastric omphalocele 2) Cleft sternum 3) Anterior diaphragmatic hernia (Morgagni) 4) Absent pericardium 5) Cardiac defects (ectopia cordis/VSD)
Tracheoesophageal anomalies: Most common
EA with distal TEF
Tracheoesophageal anomalies: EA with distal TEF, signs
1) Drooling with first feeding 2) Cyanosis secondary to laryngospasm 3) Abdominal gas
Tracheoesophageal anomalies: EA with distal TEF, clinical test
Failure to pass NGT into stomach
Palpable olive in epigastric region
Hypertrophic pyloric stenosis
Hypertrophic pyloric stenosis: Characteristics of vomitus
Non-bilous, projectile, at 2 weeks of age
Hypertrophic pyloric stenosis: Treatment
Surgical incision
Pancreas: Derived from
Foregut
Ligaments: Gastrocolic ligament connects
Greater curvature of stomach and transverse colon
Pancreas: Ventral pancreatic bud abnormally encircles 2nd part of duodenum and may cause duodenal narrowing
Annular pancreas
Pancreas: Ventral and dorsal parts fail to fuse at 8 weeks
Pancreas divisum
Spleen: Derived from
Mesoderm
Blood supply: Foregut
Celiac artery
Blood supply: Midgut
SMA
Blood supply: Hindgut
IMA
Ligaments: Connects liver to anterior abdominal wall
Falciform ligament
Ligaments: Falciform ligament, content
Ligamentum teres hepatis
Ligaments: Connects liver to duodenum
Hepatoduodenal ligament
Ligaments: Hepatoduodenal ligament, contents
Portal triad
Portal triad
1) Portal vein 2) Hepatic artery 3) Common bile duct
Ligaments: Hepatoduodenal ligament, compressed between thumb and index finger in the omental foramen to stop bleeding
Pringle maneuver
Ligaments: Liver to lesser curvature of stomach
Gastrohepatic ligament
Ligaments: Gastrocolic ligament connects
Greater curvature of stomach and transverse colon
Ligaments: Gastrocolic ligament, content
Gastroepiploic arteries
Ligaments: Gastrosplenic ligament connects
Greater curvature of stomach and spleen
Ligaments: Gastrosplenic ligament, content
1) Short gastrics 2) Left gastroepiploic vessels
Ligaments: Spleen to posterior abdominal wall
Splenorenal ligament
Ligaments: Splenorenal ligament, contents
1) Splenic artery and vein 2) Tail of pancreas
Derivatives of ventral pancreatic bud
1) Head 2) Main pancreatic duct 3) Uncinate process
Layers of gut wall: Erosion extends up to
Mucosa
Layers of gut wall: Ulcer extends up to
Submucosa
Frequency of slow waves: Duodenum
12/min
Frequency of slow waves: Ileum
8-9/min
Histology: Esophagus
Nonkeratinizing stratified squamous epithelium
Histology: Stomach
Gastric glands
Histology: Duodenum
Villi and microvilli
Histology: Location of Brunner’s glands
Submucosa of duodenum
Histology: Location of crypts of Leiberkuhn
1) Duodenum 2) Jejunum 3) Ileum
Histology: Plica circulares
1) Jejunum 2) Proximal ileum
Histology: Peyer’s patches
Lamina propria and submucosa of ileum
Histology: Contains largest number of goblet cells in the INTESTINE
Ileum
Histology: Colon
1) Crypts without villi 2) Goblet cells
Branches of abdominal aorta in order downwards (10)
1) Inferior phrenic artery 2) Celiac trunk 3) Left middle suprarenal artery 4) SMA 5) Right and left renal arteries 6) Left testicular/ovarian artery 7) Right testicular/ovarian artery 8) IMA 9) Bifurcation: Left and right common iliac 10) Median sacral artery
Transverse portion of duodenum (3rd part) is entrapped between SMA and aorta causing intestinal obstruction
SMA syndrome
Vertebral levels: Celiac trunk
T12
Vertebral levels: SMA
L1
Vertebral levels: Left renal artery
L1
Vertebral levels: IMA
L3
Vertebral levels: Bifurcation of abdominal aorta
L4
Watershed region
Splenic flexure
Main blood supply of stomach
Celiac trunk
Branches of celiac trunk
1) Common hepatic 2) Splenic 3) Left gastric
Sites of portosystemic anastomoses
1) Esophagus 2) Umbilicus 3) Rectum
Clinical signs of portal hypertension based on anastomoses
1) Esophageal varices 2) Caput medusae 3) Internal hemorrhoids
Portal-systemic: Esophagus
Left gastric-esophageal
Portal-systemic: Umbilicus
Paraumbilical-superficial and inferior epigastric, superior epigastric, lateral thoracic
Portal-systemic: Rectum
Superior rectal-middle and inferior rectal
Portal hypertension, management: Shunts blood to systemic circulation
TIPS
Hindgut: Derived from
Endoderm
Where endoderm and ectoderm meet
Pectinate/dentate line
Above pectinate line: Internal vs external hemorhhoids
Internal
Above pectinate line: Arterial supply
Superior rectal from IMA
Above pectinate line: Venous drainage
Superior rectal- Inferior mesenteric - Portal system
Above pectinate line: Lymphatic drainage
Deep nodes
Above pectinate line: Carcinoma
Adenocarcinoma
Below pectinate line: Internal vs external hemorrhoids
External
Below pectinate line: Carcinoma
Squamous cell carcinoma
Below pectinate line: Arterial supply
Inferior rectal from internal pudendal
Below pectinate line: Venous drainage
Inferior rectal-internal pudendal-internal iliac-IVC
Below pectinate line: Lympatic drainage
Superificial inguinal nodes
Innervation: Internal hemorrhoids
Visceral
Innervation: External hemorrhoids
Somatic
Apical surface of hepatocytes face
Bile cannaliculi
Basolateral surface of canaliculi face
Sinusoids
Liver: Sinusoids drain into
Central vein
Liver: Central vein drains into
Hepatic veins-systemic circulation
Liver: Zones
1) I, periportal 2) II, intermediate 3) III, pericentral vein or centrilobular
Liver: Blood flow through zones
I-II-III
Liver: Bile flow through zones
III-II-I
Liver zone: Affected first by ischemia
Zone III
Liver zone: Contains P450 system
Zone III
Liver zone: Most sensitive to toxic injury
Zone III
Liver zone: Site of alcohol hepatitis
Zone III
Biliary structures: Common hepatic duct is formed by
Right and left hepatic ducts
Biliary structures: Cystic duct branches from
Common hepatic duct
Biliary structures: Common bile duct is formed by
Cystic duct and common hepatic duct
Biliary structures: Common bile duct and pancreatic duct have a common opening called
Ampulla of Vater
Diaphragmatic hernia: Most common
Hiatal (through the oesophageal hiatus)
Diaphragmatic hernia: Most common hiatal hernia
Sliding hiatal hernia
Diaphragmatic hernia: Stomach in sliding hiatal hernia
Hourglass stomach
Diaphragmatic hernia: Displaced upward in sliding hiatal hernia
GE junction
Diaphragmatic hernia: Displaced upward in paraesophageal hernia
Fundus of stomach
3 layers of spermatic fascia
1) External spermatic fascia 2) Cremasteric muscle 3) Internal spermatic fascia
Indirect inguinal hernia: Protrudes through
1) Internal inguinal ring 2) External inguinal ring
Indirect inguinal hernia: Lateral vs medial to the inferior epigastric artery
Lateral
Indirect inguinal hernia: Defect
Failure of obliteration of processus vaginalis
Indirect inguinal hernia: Male vs female
Male
Indirect inguinal hernia: Sac covering
All 3 layers of spermatic fascia
Direct inguinal hernia: Protrudes through
1) Hesselbach’s (inguinal) triangle in the abdominal wall 2) External inguinal ring
Direct inguinal hernia: Sac covering
External spermatic fascia
Direct inguinal hernia: Population
Older men
Direct inguinal hernia: Lateral vs medial to the inferior epigastric artery
Medial
Where common iliac veins come together to form IVC
L4-L5
Where lymph nodules are located in the GIT wall
Lamina propria of mucosa
GI Histology: Mucosal epithelium
Simple cuboidal/columnar
GI Histology: Lamina propria
Blood and lymphatic vessels
GI Histology: Muscularis mucosa
Inner circular, outer longitudinal
GI Histology: Submucosa
Blood vessels, lymphatics, connective tissue, Meissner plexus
GI Histology: Serosa
Connective tissue
GI Histology: Esophagus, muscularis mucosa
LONGITUDINAL smooth muscle
GI Histology: Esophagus, muscularis externa
1) Upper 3rd: Striated 2) Middle 3rd: Striated + smooth 3) Lower 3rd: Smooth
GI Histology: SI mucosa
1) Villi and microvilli (brush border) 2) Mucus-secreting goblet cells 3) Absorptive enterocytes
GI Histology: Frequency of villi and microvilli in SI (greatest to least)
Duodenum > jejunum > ileum
GI Histology: SI (duodenum, jejunum, ileum) and LI mucosal glands
Crypts of Leiberkuhn
GI Histology: Duodenal submucosa
Brunner glands
Brunner glands secrete
Alkaline secretion (HCO3)
Atrophy vs hypertrophy of Brunner glands: PUD
Hypertrophy
GI Histology: Plicae circulares are found
Submucosa of jejunum and ileum
GI Histology: Aggregates of nodules of UNENCAPSULATED lymphatic tissue
Peyer’s patches
GI Histology: Where Peyer’s patches are found
Ileal lamina propria and submucosa
GI Histology: Cells that overlie Peyer’s patches
M cells
GI Histology: M cells, function
APCs
GI Histology: Colonic mucosa
Smooth, devoid of villi
GI Histology: Muscularis externa of colon
3 longitudinally oriented bundles, taenia coli
GI ligaments
Ligamentum teres hepatis is an embryological remnant of
Left umbilical vein
A fold of peritoneum extending from stomach to adjacent abdominal organs
Omentum
Double layer of peritoneum extending from liver to lesser curvature of stomach and proximal part of duodenum
Lesser omentum
Lesser omentum consists of (2)
1) Hepatogastric ligament 2) Hepatoduodenal ligament
Connects liver to lesser curvature of stomach
Hepatogastric ligament
Hepatogastric ligament, content
Left and right gastric arteries
Hepatogastric ligament, separates what 2 structures
Right greater and lesser sacs
Structure that may be cut during surgery to access the lesser sac
Hepatogastric ligament
Hepatoduodenal ligament, content
Porta hepatis
Porta hepatis consists of
1) Portal vein 2) Hepatic artery 3) CBD
Lesser sac communicates with greater sac through
Epiploic foramen of Winslow
Epiploic foramen of Winslow is located where
Posterior to the free edge of the lesser momentum (hepatoduodenal ligament)
A temporary cross-clamping of hepatoduodenal ligament containing portal triad at epiploic foramen (of Winslow) for control of hepatic bleeding during liver surgery or donor hepatectomy for living liver transplantation
Pringle maneuver
Where index finger is passed for Pringle maneuver
From the greater sac, through the epiploic foramen, and into the lesser sac
Structure compressed in the Pringle maneuver
Hepatic artery
A quadruple layer of peritoneum that hangs down like an apron from the greater curvature of the stomach and proximal part of the duodenum
Greater omentum
Greater momentum consists of
1) Gastrosplenic 2) Splenorenal 3) Gastrocolic ligaments
Connects greater curvature of the stomach to the spleen
Gastrosplenic ligament
Gastrosplenic ligament, separates what 2 structures
Left greater and lesser sacs
Connects the spleen to the posterior abdominal wall
Splenorenal ligament
Splenorenal ligament, runs between what 2 structures
1) Hilum of spleen 2) Left kidney
Gastrocolic ligament, contents
Left and right gastroepiploic arteries
Liver histology
Portal vein supplies ___% of liver blood supply
75
T/F Portal vein carries deoxygenated blood
T
Central veins empty into
Sublobular veins
Sublobular veins of the liver converge to form
Hepatic veins
Pores of liver sinusoids are __nm in diameter
100-200
T/F A basement membrane lies between vascular endothelium and underlying hepatocytes
F
Lies between basal surfaces of hepatocytes and basal surface of endothelial cells
Space of Disse
Site of exchange of materials between blood and hepatocytes
Space of Disse
Functional unit of hepatic parenchyma
Liver acinus
First liver cells affected by viral hepatitis
Cells in zone 1 (periportal)
Liver zone that contains CY450 enzyme system
Zone III
First liver cells affected by ischemia
Cells in zone III
First liver cells affected by alcoholic hepatitis
Cells in zone III
Liver cells most sensitive to toxic injury
Zone III cells
Anal canal is divided into
1) Upper 2/3, visceral 2) Lower 1/3, somatic
Anal canal: Upper 2/3 is derived from
Endoderm (hindgut)
Anal canal: Lower 1/3 is derived from
Ectoderm (proctodeum)
Anal canal: Location of pectinate line
Inferior limit of anal valves
Anal canal, upper 2/3: Epithelial lining
Simple columnar
Anal canal, upper 2/3: Lymphatic drainage
Internal iliac LN
Anal canal, lower 1/3: Lining epithelium
Stratified squamous
Anal canal, lower 1/3: Venous drainage
Inferior rectal vein > internal pudendal vein > IVC
Anal canal, lower 1/3: Innervation
Inferior rectal from pudendal nerve
Femoral sheath: ___cm deep to the inguinal ligament
3-4
Femoral sheath: Contents
1) Femoral artery 2) Femoral vein 3) Femoral canal
T/F Femoral canal encloses the femoral nerve
F
Femoral sheath: Lateral compartment
Femoral artery
Femoral sheath: Intermediate compartment
Femoral vein
Femoral sheath: Medial compartment
Femoral canal
Femoral canal: Contents
1) Loose CT 2) Fat 3) Lymphatics 4) Deep inguinal LN of Cloquet
Base of femoral canal
Femoral ring (superior end)
Femoral triangle, boundaries: Superior
Inguinal ligament
Femoral triangle, boundaries: Lateral
Sartorius
Femoral triangle, boundaries: Medial
Adductor longus
Femoral triangle, boundaries: Floor (3)
PIA 1) Pectineus 2) Iliopsoas 3) Adductor longus
Femoral triangle, boundaries: Roof
1) Fascia lata 2) Cribriform fascia
Femoral triangle: Contents (Lateral to medial)
NAVeL 1) Femoral nerve 2) Artery 3) Vein 4) Empty 5) Lymphatics
Internal inguinal ring: Lies in
Transversalis fascia
Internal inguinal ring: Relation to inferior epigastric vessels
Lateral
External inguinal ring: Shape
Triangular
External inguinal ring: Lies in
External oblique aponeurosis
External inguinal ring: Relation to inferior epigastric vessels
Medial
External inguinal ring: Lies lateral to
Pubic tubercle
Inguinal canal, boundaries: Anterior wall
External and internal oblique aponeuroses
Inguinal canal, boundaries: Posterior wall
Transversus abdominis and transversalis fascia aponeuroses
Inguinal canal, boundaries: Roof
Internal oblique and transversus abdominis
Inguinal canal, boundaries: Floor
Inguinal and lacunar ligament
Inguinal canal: Contents in males
FANO x 3 1) Fascia: internal spermatic, cremasteric, external spermatic 2) Arteries: Testicular, artery to vas deferens, artery to cremaster 3) Nerves: Ilioinguinal, genital branch of genitofemoral, autonomics 4) Others: Vas deferens, pampiniform plexus, testicular lymphatics
Inguinal canal: Contents in females
1) Ilioinguinal nerve 2) Round ligament of uterus
Vertebral level: Gonadal artery
L2 (left higher than right)
Branches of SMA (3)
1) Inferior pancreaticoduodenal 2) Middle colic 3) Right colic
Inferior pancreaticoduodenal artery supplies
1) Distal duodenum 2) Head of pancreas
Middle colic artery supplies
Proximal 2/3 of transverse colon
Right colic artery supplies
Ascending colon
Branches of IMA (3)
1) Left colic 2) Sigmoid 3) Superior rectal
Left colic artery supplies
1) Distal 1/3 of transverse colon 2) Descending colon
Sigmoid artery supplies
1) Descending colon 2) Sigmoid colon
Superior rectal artery supplies
Superior 2/3 of rectum
Renal arteries supply
1) Kidneys 2) Adrenal glands
Vessel that accompanies vas deferens
Testicular artery
Ovarian artery enters what ligament
Suspensory ligament of the ovary
Innervation: Foregut
Vagus
Innervation: Midgut
Vagus
Innervation: Hindgut
Pelvic
Arterial anastomoses that compensate for abdominal aorta blockage
1) Superior epigastric from internal thoracic from subclavian AND Inferior epigastric from external iliac 2) Superior pancreaticoduodenal (celiac trunk) and inferior pancreaticoduodenal (SMA) 3) Superior rectal (IMA) and middle rectal artery (internal iliac)
Celiac trunk
Left gastroepiploic artery is a branch of
Splenic
Right gastroepiploic artery is a branch of
Gastroduodenal
Right gastric artery is a branch of
Hepatic artery
Portosystemic anastomoses: Anastomose at esophagus
Left gastric (esophageal branch) and esophageal (branch of azygos) veins
Portosystemic anastomoses: Anastomose at the umbilicus
Paraumbilical and superficial & inferior epigastric
Portosystemic anastomoses: Anastomose at the rectum
Superior rectal and middle & inferior rectal
Innervation of Meissner’s plexus
PSY and SY
Innervation of Auerbach’s plexus
PSY and SY
Biliary structures
Largest branch of the splenic artery
Left gastroepiploic artery
Largest branch of the celiac trunk
Splenic artery
