First Aid Embryology Flashcards
Foregut consists of
esophagus to the upper duodenum
Midgut consists of
lower duodenum to proximal 2/3 of transverse colon
Hindgut consists of
distal 1/3 of transverse colon to anal canal above pectinate line
Mid gut development
6th week - physiologic midgut herniates through umbilical ring
10th week - returns to abdominal cavity + rotates around superior mesenteric artery (SMA) total 270° counterclockwise
Ventral wall defects
developmental defects due to failure of rostral fold closure (eg sternal defects [ectopia cordis]), lateral fold closure (eg, omphalocele, gastroschisis), or caudal fold closure (eg, bladder exstrophy)
Gastroschisis etiology
Extrusion of abdominal contents through abdominal folds (typically right of the umbilicus)
Gastroschisis coverage
not covered by peritoneum or amnion
“The abdominal contents are coming out of the G”
Gastroschisis associations
cot associated with chromosome abnormalities
Gastroschisis overview
TBD
Omphalocele etiology
Failure of lateral walls to migrate at the umbilical ring -> persistent midline herniation of abdominal contents into umbilical cord
Omphalocele coverage
Surrounded by peritoneum (light gray shiny sac)
“Abdominal contents are sealed in the O”
Omphalocele associations
Associated with congenital anomalies
- trisomy 13
- trisomy 18
- Beckwith-Wiedermann syndrome
And other structural abnormalities
- cardiac
- GU
- neural tube
Omphalocele overview
TBD
Description of Congenital umbilical hernia
failure of the umbilical ring to close after physiologic herniation of the intestines
Small defects usually close spontaneously
Tracheoesophageal anomalies
Esophageal atresia with distal tracheoesophageal fistula (TEF) is the most common (85%) and often presents as polyhydramnios in utero (due to inability of fetus to swallow amniotic fluid).
Neonates drool, choke and vomit with first feeding, TEFs allow air to enter the stomach (visible on CXR)
Cyanosis is 2° to laryngospasm (to avoid reflux-related aspiration
Clinical test: failure to pass nasogastric tube into stomach
Clinical test for Esophageal Atresia w/ distal TEF
Clinical test: failure to pass nasogastric tube into stomach
TEF AKA
Tracheoesophageal fistula
Describe H-type TEF
the fistula resembles the letter H
Describe pure Esophageal Atresia
CXR shows gasless abdomen
Identify structures and pathology
Describe presentation of intestinal atresia
Present with bilious vomiting and abdominal distension within first 1-2 days of life
What is duodenal atresia?
Caused by failure of duodenum to recanalize
Duodenal atresia is a condition in which the first part of the small bowel (the duodenum) has not developed properly. It is not open and cannot allow the passage of stomach contents.
Duodenal atresia associations
- Associated with “double bubble” (dilated stomach, proximal duodenumm) on x-ray
- Associated with down syndrome
Jejunal and ileal atresia description
Jejunal or ileal Atresia is a birth defect in which the fold of the stomach membrane needed to connect the small intestine to the back wall of the abdomen is, in part, absent. As a result, a portion of the small intestine (the jejunal) twists about one of the arteries to the colon. This twisting may be so severe that the artery in question is completely blocked (atrasia). It is sometimes compared to an apple peel in appearance.
disruption of mesenteric vessels -> ischemic necrosis -> segmental resorption (bowel discontinuity or “apple peel”)
What is the most common cause of gastric outlet obstruction in infants?
Hypertrophic pyloric stenosis
Signs of hypertrophic pyloric stenosis
- Palpable olive-shaped mass in the epigastric region
- visible peristaltic waves
- nonbilious projectile vomiting around 2-6 weeks old
hypertrophic pyloric stenosis is most common in?
Firstborn males
Hypertrophic pyloric stenosis associations
associated with exposure to macrolides
Imaging of hypertrophic pyloric stenosis
ultrasound shows thickened and lengthened pylorus
Treatment of hypertrophic pyloric stenosis
surgical incision (pyloromyotomy)
Complications of hypertrophic pyloric stenosis
Results in hypokalemic hypochloremic metabolic alkalosis (2° to vomiting of gastric acid and subsequent volume contraction
Identify structures and pathology
Hypertrophic pyloric stenosis
Pancreas derived from?
Foregut
Pancrease development
ventral pancreatic buds contribute to uncinate process and main pancreatic duct
The dorsal pancreatic bud alone becomes the body, tail, isthmus and accessory pancreatic duct
Both ventral and dorsal buds contribute to the pancreatic head
Describe annular pancreas
abnormal rotation of ventral pancreatic bud forms a ring of pancreatic tissue -> encircles the 2nd part of the duodenum
may cause duodenal narrowing and vomiting
Pancreas divisum
ventral and dorsal parts fail to fuse at 8 weeks
common anomaly
mostly asymptomatic
but may cause chronic abdominal pain and/or pancreatitis
Spleen derived from
Spleen arises in mesentery of stomach (hence is mesenchymal) but has foregut supply (celiac trunk -> splenic artery)
Retroperitoneal structures
SAD PUCKER
Suprarenal (adrenal) glands
Aorta and IVC
Duodenum (2nd through 4th parts
Pancreas [except tail]
Ureters
Colon (descending and ascending)
Kidneys
Esophagus [thoracic portion]
Rectum (partially)
Identify structures
Identify structures
Falciform ligament connects
Liver to anterior abdominal wall
Falciform ligament structures contained
ligamentum teres hepatis (derivative of fetal umbilical vein)
Patent paraumbilical veins
Falciform ligament is derived from
derivative of ventral mesentery
Hepatoduodenal ligament connects
liver to duodenum
Hepatoduodenal ligament structures contained
Portal triad
(Proper hepatic artery, portal vein, common bile duct)
Describe the Pringle maneuver
- The Hepatoduodenal ligament may be compressed between thumb and index finger placed in omental foramen to control bleeding
Hepatoduodenal ligament location
Part of the lesser omentum
Borders the omental foramen which connects the greater and lesser sacs
Gastrohepatic ligament connects
liver to lesser curvature of stomach
Gastrohepatic ligament structures contained
Gastric vessels
Gastrohepatic ligament location
Part of the lesser omentum and connects liver to lesser curvature of the stomach and separates greater and lesser sacs on the right
Sugical considerations of gastrohepatic ligament
May be cut during surgery to access the lesser sac
This May be cut during surgery to access the lesser sac
Gastrohepatic ligament
Gastrocolic ligament connects
Greater curvature of stomach and transverse colon
Gastrocolic ligament structures contained
gastroepiploic arteries
Gastrocolic ligament location
part of the greater omentum and connects the greater curvature of the stomach to the transverse colon
Gastrosplenic ligament connects
greater curvature of the stomach and spleen
Gastrosplenic ligament structures contained
short gastrics
left gastroepiploic vessels
Gastrosplenic ligament location
- Separates greater and lesser sacs on the left and connects the greater curvature of the stomach and the spleen
- Part of the greater omentum
Splenorenal ligament connects
Spleen to posterior abdominal wall
Splenorenal ligament structures contained
- Splenic artery and vein
- vein of pancreas
Identify structures
