Term
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Definition
Celiac trunk
PNS: vagus nerve
SNS: T5-T12, celiac ganglion
Derivatives:
Esophagus
Stomach
Duodenum (1st and 2nd parts)
Liver
Pancreas
Biliary apparatus
Gallbladder |
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Term
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Definition
Superior mesenteric artery
PNS: vagus
SNS: T5-T12, superior mesenteric ganglion
Duodenum (2nd-4th parts)
jejunum
ileum
cecum
appendix
ascending colon
proximal 2/3 transverse colon
Undergoes physiological umbilical "herniation" (re elongation) from wks 6-9
- cranial limb grows rapidly to form most of the SI
- caudal limb develops a cecal swelling -> cecum and vermiform appendix
Rotation of midgut loop
- herniated loop rotates 90 degrees counterclockwise around the SMA, continues, total 270 degrees rotation
- with reduction of "hernia," SI returns first, passing posterior to SMA
- future colon enters last to take a position on the right side of the abdomen
- caudal part forms part of the transverse colon and the cranial part elongates to form the ascending colon, bringing the cecum and the appendix to the right iliac fossa
Recanalization |
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Term
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Definition
Inferior mesenteric artery
PNS: pelvic splanchnic nerves
SNS: L1-L2, inferior mesenteric ganglion
distal third-splenic flexure of transverse colon
descending colon
sigmoid colon
rectum
anal canal (above pectinate line)
Desc colon becomes retroperitoneal
Sigmoid colon keeps its mesentery
Cloaca
- ends at cloacal membrane which separates the endodermally-lined cloaca from the ectodermally-lined proctoderum
- allantois empties into cloaca
Partitioning of the cloaca
- urorectal septum fuses with clocal membrane, dividing it dorsal/ventral
- urorectal septum divides cloacal sphincter into external anal sphincter and anterior muscles
Cloaca and Proctodeum
- The anal membrane ruptures at end of week 8
- Anal canal develops from 2 sources.
Superior 2/3 from hindgut (endoderm epithelium)
inferior 1/3 from proctodeum (ectoderm epithelium) the junction is at the pectinate line
- The different sources lead to different blood supply, venous and lymphatic drainage and nerve supply. Autonomic nerves (hindgut) vs somatic sensory (proctodeum) painless (hindgut) or painful (proctodeum) carcinomas |
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Term
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Definition
Reaches normal length - wk 7
Failure to lengthen -> congenital hiatal hernia (gastroesophageal junction displaced above the diaphgram)
Lumen fills in, recanalizes by end of embryonic period
Caudal branchial arches -> striated m
Splanchnic mesoderm -> smooth m
Innervated by the vagus |
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Term
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Definition
Esophageal atresia
I/c amniotic fluid -> blockage of amniotic fluid circulation |
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Term
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Definition
First visible in 4th wk
Dorsal edge grows faster, bulges dorsally -> greater curvature
90 degree rotation in longitudinal axis so left side becomes anterior (left vagus) and right side becomes posterior (right vagus)
Dorsal mesentery
- gastrosplenic lig.
- lienorenal lig.
- greater omentum
Ventral mesentery
- lesser omentum
- falciform lig.
- coronary lig. |
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Term
| Congenital hypertrophic pyloric stenosis |
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Definition
most common congenital anomaly of stomach
4-6:1 M:F ration
Projectile vomiting |
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Term
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Definition
Develops from caudal foregut and cranial midgut
Celiac and superior mesenteric arteries
Secondarily retroperitoneal with rotation of the stomach
Lumen fills then recanalizes, just like esophagus |
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Term
| Duodenum - abnormal development |
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Definition
Atresia
- Failure to recanalize -> polyhydramnios (if distal to bile duct you get bile-stained vomit)
- "double bubble" sign in imaging
Stenosis: failure of recanalization usually caudal to bile duct
Failure of recanalization can cause either of these |
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Term
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Definition
Foregut
Hepatic diverticulum grows into the septum transversum (splanchnic mesoderm) and forms the hepatocytes and lining of the biliary tree
- hepatic diverticulum (mesoderm) -> hepatic cords, epithelial lining of biliary apparatus
- other tissue components are derived from septum transversum mesoderm
Anomalies: variations in extrahepatic biliary tree
- extrahepatic biliary atresia is NOT a developmental defect
Smaller caudal part forms the gallbladder |
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Term
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Definition
Foregut
Two buds - ventral and dorsal
- dorsal grows into dorsal mesoduodenum and dorsal mesogastrium
- eventually fuse, combine duct systems
Annular pancreas
- 2nd part of duodenum is surrounded by a ring of pancreatic tissue
Ectopic pancreas
- pancreatic tissue outside the normal site (stomach, SI, Meckel's d) |
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Term
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Definition
NOT part of the foregut, although the splenic artery is a branch of the celiac trunk
Derived from mesenchymal cells in the dorsal mesogastrium beg. wk 5
- as mesogastrium swings to the left, a portion fuses with the posterior abdominal wall over the kidney
Accessory spleens can be found in dorsal mesogastrium, the walls of the stomach, or elsewhere |
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Term
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Definition
Fixation - most of duodenum and head of pancreas become retroperitoneal due to rotation of stomach and duodenum
Ascending colon becomes retroperitoneal
Attachment of SI runs from duodenojejunal jn inferolaterally to the ileocecal jn |
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Term
Developmental anomalies of the midgut
(or not)
Meckel's diverticulum
Appendiceal variations
Stenosis, atresia |
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Definition
Omphalocele
- persistent "hernia"
- bowel covered by peritoneum
- umbilical cord arises from sac
Gastroschisis (NOT A MIDGUT ANOMALY)
- abdominal wall defect
- bowel not covered by amnion
- defect usually to right of umbilicus, possibly due to excessive resorption of right umbilical vein
- more common in males
Malrotation
Omphalomesenteric Duct anomalies
- various problems where an ileal diverticulum attaches to the umbilicus - fistulas, cysts, diverticula, etc
Meckel's diverticulum
- 2%, 2 ft, 2 in
- can contain ectopic gastric mucosa or ectopic pancreas
- perforation - can mimic appendicitis
Appendix
- may alter clinical presentation or present a problem
- can be preileal, pelvic, subcecal, etc...
Stenosis and atresia
- Failure of recanalization or interruption of blood flow
- most common cause of intestinal obstruction
- obstruction most often in ileum (50%) and duodenum (25%) |
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Term
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Definition
| Derived from vagal and sacral neural crest |
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Term
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Definition
absence of intramural autonomic ganglion cells in the affected region of colon with distension (megacolon) cranial to the affected region
most common cause of colonic obstruction
accounts for 33% of all neonatal obstructions
1 in 5400-7200 live births. Males>females (4:1). More common in trisomy 21
Thought to be caused by abnormal migration of neural crest.
Abnormal portion is resected. |
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