Embryo Flashcards
Derivatives of Endoderm
Epithelium (except mouth and anal canal)
Mesoderm
Splanchnic
Smooth mm. And CT
Ectoderm
Mouth and anal canal
Neural Crest
ANS
Foregut
Pharynx/derivatives Respiratory system Esophagus Stomach Liver/pancreas Biliary apparatus Proximal duodenum
Midgut
Small intestine
Cecum/appendix
Ascending colon
R. 1/2 transverse colon
Hindgut
L. 1/2 transverse colon Descending colon Sigmoid colon Rectum Superior anal canal Epithelium of urinary bladder/urethra
Foregut vessel
Celiac Trunk
Midgut vessel
SMA
Hindgut vessel
IMA
Skeletal muscle of esophagus
Pharyngeal arches 4 & 6
Smooth muscle of esophagus
Splanchnic mesoderm
LARP (stomach development/rotation)
Left Anterior
Right Posterior
Hypertrophic Pyloric Stenosis
Hypertrophy of circular and some longitudinal muscles in the pylorus
Presentation:
- Post-feeding (nonbilious) projectile vomiting
- Few stools
- Fail to gain weight
*Possible olive-like mass @ L1
Pancreas (dorsal primordia)
Body
Tail
Part of Head
Pancreas (ventral primordia)
Head
Unicate process
(Main duct is from ventral duct)
Pancreatic Rotation
When duodenum rotates right, ventral pancreatic bud goes dorsally
Annular Pancreas
When ventral bud becomes bifed and rotates to the left to fuse with dorsal bud around 2nd part of duodenum
**Can lead to obstruction in duodenum (with bilious vomit)
Midgut Rotation
Leaves abdominal cavity for umbilicus @ W6 (returns @ W10)
Rotates 90* in umbilical cord (then another 180* in return) (Total 270* rotation)
SMA herniates out into umbilical cord @ W6 (liver grows too much)
Returns @ W10 when body has grown enough
Omphalocele
W10
Failure of bowel to return to body cavity
*not an umbilical hernia
Gastroschisis
W4 Failure of anterior ab. Wall to close
Hirschsprung’s Disease
Absence of ganglion cells (d/t failure of Neural crest migration)
Leads to mega colon (d/t loss of motility, feces get “stuck”)
Congenital Diaphragmatic Hernia
Herniation of abdominal organs into thoracic cavity
D/t failure of diaphragmatic components to fuse properly
Nonrotation of Midgut
SI sits on right side
LI on left side
Side-by-side
Reversed Rotation of Midgut
Duodenum become anterior to transverse colon (possible colon obstruction)
Meckel’s Diverticulum
Abnormality of Vitelline duct (it normally regresses)
Causes a projection from ileum to abdominal wall
Rule of 2s
- 2 year olds
- 2 inches long
- 2x more likely in M vs. F
- 2 types of ectopic tissue (gastric and pancreatic)
- 2% population
- 2 ft. From IC Jxn
Urorectal Septum
Grows toward cloacal membrane
Divides into urogenital membrane and anal membrane
Composed of Endo/ectoderm (no mesoderm because we need to open it up)
Anal Canal
Superior portion from Hindgut
Inferior portion from proctodeum
Superior Anal canal
Upper 2/3
Blood: IMA
Nerves: ANS
Lymph: Inf. Mesenteric LNs
Inferior Anal Canal
Lower 1/3
Blood: middle/inf. Rectal aa.
Nerves: Pudendal n. (Somatic)
Lymph: Sup. Inguinal LNs
Anorectal Malformations
Occur if Endo/ectoderm do not meet up properly
Septum should migrate and separate the cloaca
Pleura-peritoneal Membrane
Septum Transversum meets with pleuroperitoneal membranes (somatic layer of lateral plate)
Diaphragm Formation
Septum Transversum (central tendon)
Pleuroperitoneal membranes
Dorsal mesentery of esophagus (cruras)
Congenital Diaphragmatic Hernia
Results from defective formation/fusion of pleuroperitoneal membranes
Opening in foremen of Bochdalek (most on Left side)
Associated with hypoplastic lungs/polyhydramnios
Peritoneal Cavity
Mesentery is double layer of serous membrane
Dorsal mesentery- attaches to posterior wall
Ventral mesentery- attaches to anterior wall
*Splanchnic Mesoderm
Dorsal Mesocardium
Degenerates leaving the transverse pericardial sinus
Dorsal mesogastrium
Greater Omentum (4 total layers)
Splenorenal l.
Gastrosplenic l.
Ventral Mesogastrium
Lesser Omentum
Ventral Mesentery
Falciform L.
Mesoduodenum
Mesentery around duodenum
Mesentery proper
Mesentery containing jejunum and ileum
Mesocolon
Mesentery around transverse colon and sigmoid colon
Mesorectum
Mesentery around rectum
Thoracic Esophagus and Anus
RETROPERITONEAL
Intraperitoneal Structures
Stomach Tail of pancreas 1st part of duodenum Jejunum Ileum Transverse colon Sigmoid colon
Retroperitoneal Structures
Pancreas (except tail)
Ascending/Descending colon
Duodenum (2,3,4th parts)
