Abdominal Aorta

• Branches of the abdominal aorta

  • Celiac
  • Superior mesenteric
  • Inferior mesenteric
  • Suprarenal
  • Renal
  • Gonadal
  • Inferior phrenic
  • Lumbar
  • Common iliac
  • Median sacral
• Primitive gut (endoderm) divisions


  1. Foregut - supplied by Celiac trunk

  2. Midgut - Sup. Mesenteric artery

  3. Hindgut - Inf. Mesenteric artery
• Anterior unpaired visceral arteries

  • Celiac
  • Superior mesenteric
  • Inferior mesenteric
• Lateral paired visceral arteries


  • Suprarenal
  • Renal
  • Gonadal
• Lateral paired abdominal arteries

  • Inferior phrenic
  • Lumbar
• Terminal branches of abdominal aorta

  • Common iliac
  • Median sacral
• Primitive gut


  Formed from the incorporation of the dorsal part of the yolk sac into the developing embryo- 4th week
• Primitive gut


  • Lining epithelium and the glands arised from the endoderm
  • Visceral mesoderm (muscular, connective tissue, other layers)
  • Craniocaudal and Lateral folding of the embryo
• Divisions of the primitive gut

  • Foregut
  • Midgut
  • Hindgut
• Foregut


  Cranial portion, supplied by Celiac trunk (artery and branches)
• Midgut


  Middle portion, supplied by the Superior Mesenteric artery
• Hindgut


  Caudal portion, supplied by the Inferior Mesenteric artery
• Foregut derivatives


  • Primordial pharynx and its derivatives (oral cavity, pharynx, tongue, tonsils, salivary glands, upper respiratory)
  • Lower respiratory system
  • Esophagus and stomach
  • Upper 2nd part of the duodenum (proximal to the opening of bile duct)
  • Liver, biliary apparatus (hepatic ducts, Gall bladder, and Bile duct) and Pancreas
• Midgut derivatives


  • Duodenum (2nd part)
  • Small intestine
  • Cecum, Vermiform appendix, Ascending colon, and the right half or the upper two thirds of the Transverse colon
• Hindgut derivatives


  • Transverse colon (left 1/3)
  • Descending colon and Sigmoid colon
  • Rectum and Superior part of the Anal canal
  • Epithelium of the urinary bladder and most of the urethra
• Duodenum (2nd part) is classified under both Midgut and Foregut derivatives
• Transverse colon is classified as both Midgut and Hindgut derivatives
• Development of esophagus


  1. Laryngotracheal tube diverticulum or tracheoesophageal diverticulum arising from the ventral border of the foregut

  2. Initially you have a common opening between the respiratory and the digestive tracts

  3. Tracheoesophageal folds fuse in the midline to form a septum

  4. Foregut is divided into esophagus (dorsally) and trachea (ventrally) because of the formation of the tracheaesophageal septum
• Esophagus development


  • Initially short but elongates rapidly because of the growth and relocation of the heart and lungs
  • Epithelium and glands are derived from the endoderm
  • Recanalization occurs at the end of 8th week
• Esophageal anomalies


  • Esophageal atresia
  • Esophageal stenosis
  • Tracheoesophageal Fistula (TEF)
• Esophageal atresia


  Failure of recanalization (8th week), associated with TEF, no lumen at all, the proximal part of the esophagus ends as a blind pouch, usually results in Polyhydramnios
• Esophageal stenosis


  There is a formation of the tube but lumen is narrowed (8th week) resulting to obstruction, involves the midportion of the esophagus, caused by hypertrophy of the submucosal/muscularis externa or incomplete recanalization
• Tracheoesophageal Fistula (TEF)


  Abnormal communication between the trachea and the esophagus, always associated with Esophageal atresia, caused by improper division of the foregut by the tracheoesophageal septum
• Types of TEF


  • Esophageal atresia with TEF at the distal end (most common)
  • TEF only (between trachea and esophagus)
  • Esophageal atresia with TEF at proximal end
  • Esophageal atresia with TEF at distal and proximal ends
• Clinical features of TEF

  • Excessive accumulation of saliva or mucus in the nose and mouth
  • Episodes of gagging and cyanosis after swallowing milk
  • Abdominal distention after crying
  • Reflux of gastric contents into the lungs, causing Pneumonitis
• Development of stomach


  1. 4th week- a slight dilation (indicates the site of primordial stomach) is seen

  2. Fusiform dilatation -> primitive stomach

  3. The next 2 weeks, the dorsal/posterior (left) part grows faster than the ventral/anterior (right) -> resulting to greater (dorsal part) and lesser (ventral part) curvatures

  4. Rotates 90 degrees clockwise

  5. As a result of rotation, the Dorsal mesentery is carried to the Left and eventually forms the Greater Omentum
• Parts of the stomach

  Cardinal, Fundus, Body, and Pyloric
• Hypertrophic Pyloric Stenosis


  Muscularis externa in the pyloric region hypertrophies resulting into a narrow lumen that could obstruct the passage of food
• Clinical features of Hypertrophic Pyloric Stenosis

  • Projectile/forceful vomiting immediately after feeding
  • A small palpable mass at the right costal margin
• Development of duodenum


  1. Early 4th week- duodenum begins to develop from caudal portion of the foregut (upper duodenum) and cranial part of the midgut (lower duodenum)

  2. Duodenum is both foregut (2nd part, proximal to the opening of the bile duct) and midgut (2nd part, distal to the opening of the bile duct)
• Blood supply of duodenum

  • Superior pancreaticoduodenal artery
  • Inferior pnacreaticoduodenal artery
• Duodenal anomalies


  • Duodenal stenosis
  • Duodenal atresia
• Duodenal stenosis


  Involves the 3rd and 4th portion, narrow lumen, caused by incomplete recanalization
• Duodenal atresia


  Involves the 2nd and 3rd portion, no lumen, "Double Bubble Sign"
• Development of liver


  1. Hepatic Diverticulum arises from the distal part of the foregut (early 4th week), cranial part forms the liver, caudal part forms the gallbladder & cystic duct

  2. Endodermal lining of the Foregut forms an outgrowth (Hepatic diverticulum) into the surrounding mesoderm of the Septum Transversum

  3. Growth of the liver bulges into the abdominal cavity that stretches the Septum Transversum to form the Ventral Mesentery containing the Falciform ligament and the Lesser omentum

  4. Umbilical vein regresses to form the ligamentum teres

  5. Connection between the hepatic diverticulum and the foregut narrows to form the Bile duct

  6. An outgrowth of the bile duct gives rise to the Gall Bladder rudiment and Cystic duct

  7. Bile formation starts at 12th week
• Extrahepatic biliary atresia


  Obstruction of the ducts at/or superior to the porta hepatis, failure of the bile duct to canalize, results from liver infection during late fetal life, causes jaundice soon after birth, treated by surgical correction
• Development of pancreas


  1. Develops between the layers of the mesentery from dorsal and ventral pancreatic buds of the endodermal cells

  2. 5th-8th weeks the dorsal and ventral pancreatic bud develops

  3. Dorsal pancreatic bud appears first and forms the reminder of the pancreas- head, body and tail

  4. Ventral pancreatic bud forms most of the head of the pancreas (including the uncinate process)

  5. As the duodenum rotates to the right and becomes C-shaped, the ventral pancreatic bud is carried dorsally with the bile duct

  6. The ventral pancreatic bud soon lies posterior to the dorsal pancreatic bud and later fuses with it

  7. Main pancreatic duct is formed by the union of the distal part of the dorsal pancreatic duct and the entire ventral pancreatic duct
• Development of pancreas


  1. Develops between the layers of the mesentery from dorsal and ventral pancreatic buds of the endodermal cells

  2. 5th-8th weeks the dorsal and ventral pancreatic bud develops

  3. Dorsal pancreatic bud appears first and forms the reminder of the pancreas- head, body and tail

  4. Ventral pancreatic bud forms most of the head of the pancreas (including the uncinate process)

  5. As the duodenum rotates to the right and becomes C-shaped, the ventral pancreatic bud is carried dorsally with the bile duct

  6. The ventral pancreatic bud soon lies posterior to the dorsal pancreatic bud and later fuses with it

  7. Main pancreatic duct is formed by the union of the distal part of the dorsal pancreatic duct and the entire ventral pancreatic duct

  8. Proximal part of the dorsal pancreatic duct usually obliterates, but it may persist as an accessory pancreatic bud
• Ventral pancreatic duct


  • It rotates, after rotation it will fuse with the dorsal pancreatic bud
• Annular Pancreas is a congenital anomaly