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Embryology Review
N/A
131
Anatomy
Graduate
12/14/2011

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Cards

Term
What are the three mesodermal germ layers of the trilaminar germ disc?
Definition
Paraxial, intermediate, and lateral plate mesoderm
Term
When does mesoderm differentiate into its three germ layers?
Definition
3rd week of development
Term
When does the respiratory diverticulum (lung bud) appear in embryonic development?
Definition
4th week
Term
Tracheoesophageal ridges fuse to form what?
Definition
Tracheoesophagel septum
Term
What does the tracheoesophageal septum separate?
Definition
Dorsal esophagus from the ventral trachea
Term
What maintains communication between the esophagus and the pharynx?
Definition
Laryngeal orifice/inlet
Term
What defect is known as esophageal atresia?
Definition
Upper part of esophagus remains a blind pouch with the lower segment forms a fistula with the trachea
Term
What are some possible complications of the formation of a tracheoesophageal fistula?
Definition
Pneumonia, polyhydramnios
Term
Cartilage and muscles of the larynx originate from what embryonic structures?
Definition
Mesenchyme of the fourth and sixth pharyngeal arches
Term
The intrinsic muscles of the larynx are controlled by what nerve?
Definition
Vagus
Term
The trachea is formed from what embryonic structure?
Definition
Lung bud
Term
Where does the respiratory portion of the bronchial tree begin?
Definition
Respiratory bronchioles which divide into alveolar ducts
Term
What doe alveolar ducts divide into?
Definition
Alveolar sacs
Term
What are the two types of cells found in alveolar squamous epithelium? 
Definition
Type 1 and 2 pneumocytes
Term
Flattened cells with attenuated cytoplasm that form 90% of the surface lining of alveoli are known as what?
Definition
Type 1 pneumocytes
Term
Rounded cells commonly located in obtuse angles of alveoli that are surfactant secreting cells are known as what? 
Definition
Type 2 pneumocytes
Term
When do terminal sacs/primitive alveoli first develop?
Definition
26 weeks
Term
What must be developed in order to allow for the possibility of postnatal survival with intensive care?
Definition
Terminal sacs/primitive alveoli 
Term
What fraction of adult alveoli are present at birth?
Definition
1/6
Term
What partitions the pleural cavities form the rest of the intraembryonic coelom?
Definition
Pleuropericardial membranes, Pleuroperitoneal folds
Term
What forms visceral pleura covering the outside of the lung?
Definition
Splanchnic mesoderm
Term
What innervates the visceral pleura?
Definition
GVA fibers from the pumlmonary plexus, is insensitive to pain
Term
What forms parietal pleura covering the inside of the body wall?
Definition
Somatic mesoderm
Term
What innervates the parietal pleura?
Definition
GSA fibers from intercostal nerves, very sensitive to pain
Term
The potential space between the visceral plerua and the parietal pleura is known as what?
Definition
Pleural cavity
Term
Normal development of the lung is dependant on what? 
Definition
Presence of fluid in the lung, fetal breathing moments, adequate amniotic fluid volume
Term
What are the sources of fluid in the lungs?
Definition
Secreted within the lung, some aspirated as amniotic fluid
Term
How is fetal breathing employed in the development of the lung?
Definition
Aspirating amniotic fluid and for conditioning respiratory muscles
Term
How does adequate amniotic fluid volume impact lung development?
Definition
Creates adequate space in the thoracic cavity for lung growth
Term
At birth, the lung is about half full of fluid. What routes clears the lung of fluid after birth?
Definition
Pressure on the fetal thorax during birth expels some of the fluid via the nose and mouth, resorption into respiratory capillaries, resorption into lymphatic vessels
Term
Insufficient synthesis of surfactant by type II alveolar cells (type 2 pneumocytes) is known as what disease?
Definition
Respiratory distress syndrome (hyaline membrane disease)
Term
What are the effects of respiratory distress syndrome?
Definition
Increased surface tension results in collapsed alveoli, may lead to fetal death
Term
How is respiratory distress syndrome treated?
Definition
Artifical surfactant or corticosteroid therapy
Term
Hypoplastic lung may be caused by what?
Definition
Oligohydramnios (prevents thoracic cavity expansion), congenital diaphragmatic hernia
Term
What incorpates the yolk sac into the primitive gut?
Definition
Cephalocaudal (longitudinal) and lateral (transverse) folding
Term
Where does the foregut of the primitive gut begin?
Definition
Buccopharyngeal (oropharyngeal) membrane
Term
What connects the midgut to the yolk sac?
Definition
Vitelline duct
Term
Where does the hindgut end in the primitive gut?
Definition
Cloacal membrane
Term
What are the boundaries of the pharyngeal gut?
Definition
Buccopharyngeal membrane to the respiratory diverticulum (lung bud), forms head and neck portion of the foregut
Term
The foregut, apart from the pharyngeal gut, extends between what developing structures?
Definition
Respiratory diverticulum and the liver bud
Term
What are the boundaries of the developing midgut?
Definition
From just distal to the liver blood to the junction of the right 2/3 and left 1/3 of the transverse colon (left colic flexure)
Term
What are the boundaries of the hindgut?
Definition
Distal 1/3 of the transverse colon to the cloacal membrane 
Term
What two tissues form the primitive gut?
Definition
Endoderm and splanchnic mesoderm
Term
The endoderm gives rise to what structures of the gut?
Definition
Epithelial lining of the gut, gives rise to parenchyma of glands (liver, pancreas, etc.)
Term
Splanchnic mesoderm gives rise to what structures in the gut?
Definition
Smooth muscle and connective tissue, visceral peritoneum of the gut wall 
Term
Double layers of peritoneum that suspend portions of the gut tube from the gut wall are known as what? 
Definition
Mesenteries
Term
By when are foregut, midgut, and hindgut portions of the gut suspended from the posterior abdominal wall by the dorsal mesentary?
Definition
5th week
Term
What are the divisions of the dorsal mesentary?
Definition
Dorsal mesogastrium (greater omentum), dorsal mesoduodenum, mesentary proper, dorsal mesocolon
Term
The ventral mesentary develops into what structures?
Definition
Falciform ligament and lesser omentum by division of the septum transversum
Term
The remnant of the umbilical vein can be found in what structure?
Definition
Falciform ligament
Term
Incomplete recanalization of the esophagus following an epithelial proliferation phase leads to what dysfunction? 
Definition
Esophageal stenosis
Term
A congenitally short esophagus pulling the stomach up through the esophageal hiatus is known as what abnomality?
Definition
Congenital hiatal hernia
Term
How does the primitive stomach rotate about its longitudinal axis during development?
Definition
90 degrees clockwise, original left side ends up facing anteriorly
Term

How does the primitive stomach rotate about its anteroposterior axis during development?

Definition
90 degrees, causing the lesser curvature to face upwards and the greater curvature to face downward and to the left
Term
Rotation of the primitive stomach creates what abdominal space? How?
Definition
Omental bursa behind the stomach and lesser omentum by pulling the dorsal mesogastrium to the left
Term
What anomaly is characterized by hypertrophy of the smooth muscles of the pyloric sphincter, leading to polyhydramnios and blockage of food passage into the duodenum?
Definition
Congenital pyloric stenosis
Term
Duodenal stenosis or atresia is caused by what?
Definition
Incomplete recanalization of the duodenum
Term
A "double bubble" ultrasound scan in the gut, polyhydramnios, and bile stained vomit shortly after birth are all signs indicating what dysfunction?
Definition
Duodenal stenosis or atresia
Term
The hepatic diverticulum begins as an endodermal poliferation on what other structure?
Definition
Middle of the descending duodenum
Term
What gives rise to the cystic duct, bile duct, and gallbladder?
Definition
Small ventral outgrowth on the hepatic diverticulum
Term
The hepatic diverticulum is closely related to what other endodermal poliferation?
Definition
Ventral pancreatic bud
Term
The connective tissue framework of the liver (stroma) are formed from what?
Definition
Mesoderm of the septum transversum
Term
What is an essential developmental function performed by the liver between week 6 to the 6th month of gestation?
Definition
Hematopoietic, colonized by hematopoietic cells from the aorta-gonad-mesonephros region
Term
When does bile excretion begin?
Definition
Week 12
Term
What structures form the pancreas?
Definition
Dorsal pancreatic bud in the dorsal mesentary and ventral pancreatic bud that develops near the bile duct
Term
The ventral pancreatic bud forms which structures?
Definition
Uncinate process and inferior part of the head of the pancreas, dorsal pancreatic bud forms the rest of the gland
Term
The main pancreatic duct develops from what?
Definition
Distal portion of the dorsal pancreatic duct and the entire ventral pancreatic duct
Term
The accessory pancreatic duct forms from what structure?
Definition
Proximal part of the dorsal pancreatic duct
Term
Failure of the hepatic or bile duct to recanalize following a phase of epithelial proliferation is known as what defect?
Definition
Extrahepatic biliary atresia
Term
What condition refers to two components of the ventral pancreas bud migrating in opposite directions to encircle and possibly obstruct the duodenum?
Definition
Annular pancreas
Term
The primary intestinal loop of the midgut forms what structures?
Definition
Mesentary
Term
The cephalic limb of the midgut forms what structures?
Definition
Distal duodenum, jejunum, part of the ileum
Term
The caudal limb of the midgut forms what structures?
Definition
Lower ileum, cecum, appendix, ascending colon, 2/3 of the transverse colon
Term
Rapid growth of the liver that causes intestinal loops to enter the umbilical cord is known as what?
Definition
Physiological umbilical herniation
Term
What occurs concurrently with physiological umbilical herniation?
Definition
Primary intestinal loop rotates around the superior mesenteric artery a total of 270 degrees counterclockwise
Term
When do intestinal loops return to the enlarged abdominal cavity?
Definition
10th week
Term
What develops as the cecum bud of the colon descends from the upper right quadrant to the right lower quadrant?
Definition
The Appendix
Term
What occurs when the ascending and descending colons reach their final positions?
Definition
Mesentaries fuse with the peritoneum of the posterior abdominal wall, making the organs secondarily retroperitoneal
Term
What are the divisions of the cloaca?
Definition
Anterior urogenital sinus and posterior anorectal canal
Term
What forms the segments of the cloaca?
Definition
Mesodermal urorectal septum 
Term
What is the origin of the caudal part of the anal canal below the pectinate line?
Definition
Ectoderm
Term
Failure of recanalization of the lower portion of the anal canal following epithelial proliferation is known as what?
Definition
Imperforate anus
Term
When the opening of the hindgut shifts anteriorly, the defect is known as what?
Definition
Urorectal or rectovaginal fistula
Term
Absence of autonomic parasympathetic ganglia from a segment of the intestines is known as what?
Definition
Congenital megacolon or Hirschprung's disease 
Term
The 5 paired structures arising from the aortic sac (the most distal portion of the truncus arteriosus) is known as what?
Definition
The aortic arches
Term
The aortic arches are embedded in what?
Definition
Mesenchyme of the pharyngeal arches
Term
By forming right and left horns, the aortic sac gives rise tow hat structures?
Definition
Brachiocephalic artery and proximal (ascending) segment of the aorta 
Term
The third aortic arch gives rise to what?
Definition
Common carotid, first part of internal carotid arteries, external carotid
Term
The fourth aortic arch gives rise to what?
Definition
Arch of the aorta on the left, proximal segment of righ subclavian artery on the right
Term
The fifth aortic arch gives rise to what?
Definition
Nuthin, SUCKA! It don't form good often
Term
The sixth aortic arch gives rise to what?
Definition
Proximal right pulmonary artery on the right, proximal segment of left pulmonary artery and ductus arteriosus on the left
Term
The ductus arteriosus closes shortly after birth and becomes what?
Definition
Ligamentum arteriosum
Term
Failure of ductus arteriosus to close is known as what?
Definition
Patent ductus arteriosus
Term
A patent ductus arteriosus leads to what? 
Definition
Left to right shunt
Term
What kind of coarctation of the aorta is not fatal until age 50 which is when it requires surgical correction
Definition
Postductal coarctation (vs preductal coarctation which must be corrected in infancy)
Term
When the right dorsal aorta persists, what abnormality forms?
Definition
Double aortic arch which a vascular ring forms around the trachea and esophagus, can cause difficulty breathing and swallowing
Term
The vitelline arteries eventually fuse to create what?
Definition
Celiac, superior mesentary, and inferior mesentary arteries
Term
Umbilical arteries persist after birth as what?
Definition
Internal iliac and umbilical arteries 
Term
What are the three major pairs of veins in the 5 week embryo?
Definition
Vitelline, umbilical veins, cardinal veins
Term
The vitelline vein forms what?
Definition
Hepatocardiac portion of the inferior vena cava, superior mesenteric vein
Term
The ductus venosus shunts most of the oxygenated blood from the placenta past the liver into where?
Definition
The heart for distribution to the rest of the body
Term
After birth, the left umbilical vein and ductus venosus are obliterated and form what?
Definition
Ligamentum teres hepatis, ligamentum venosum 
Term
Supracardinal veins eventually form what structures?
Definition
Azygos and hemiazygos
Term
The right anterior cardinal and common cardinal veins form what?
Definition
Superior vena cava
Term
The anastomosis between the anterior cardinal veins develops into what?
Definition
Left brachiocephalic vein
Term
The terminal portion of the left posterior cardinal veins form the left superior intercostal vein
Definition
Term
The right sacrocardinal vein forms what?
Definition
Sacrocardinal segment of inferior vena cava
Term
The inferior vena cava has segments that derive from what structures?
Definition
Vitelline, subcardinal, sacrocardinal veins
Term
Blood islands develop from what?
Definition
Mesenchymal cells in splanchnic mesoderm
Term
When do blood islands form?
Definition
Beginning of 3rd week
Term
What do blood islands eventually form?
Definition
Forms a horseshoe shaped plexus that eventually becomes endocardial tubes
Term
The cephalic central portion of blood island plexuses in front of the buccopharyngeal membrane is known as what?
Definition
Cardiogenic area
Term
How does the cardiogenic area and buccopharyngeal membrane move together during development?
Definition
Pushed ventrally and caudally and rotated 180 degrees
Term
How is the heart tube formed?
Definition
Lateral folding of the trilaminar germ disc fuses two lateral endothelial tubes 
Term
What initially separates the epimyocardial mantle from the endothelial heart tube?
Definition
Cardiac jelly
Term
What are the three layers formed by the heart tube?
Definition
Endocardium, myocardium, epicardium
Term
The future bulboventricular region of the heart arises from what?
Definition
Intrapericardial part of the heart tube
Term
The bulbus cordis contributes to what?
Definition
1/3 to right ventricle, 1/3 to outflow tracks for the ventricles, proximal portions of the aorta and pulmonary trunk
Term
The cephalad portion of the heart tube bends in what direction?
Definition
Ventrally and caudally to the right
Term
The caudal portion of the heart tube bends in what direction?
Definition
Dorsocranially and to the left
Term
When is the cardiac loop finished?
Definition
Day 28
Term
The left sinus horn gives rise to what structures?
Definition
Oblique vein of the left atrium, coronary sinus
Term
The right sinus horn becomes encorporated into what structure?
Definition
Smooth wall of right atrium
Term
What is the temporary opening between the septum primum and the endocardial cushions
Definition
Ostium primum
Term
The second crescent shaped fold that appears to the right of the septum primum that leaves the opening for the foramen ovale is known as what?
Definition
Septum secundum
Term
What is incorporated into the left atrium to form its smooth walled section?
Definition
Pulmonary vein and its tributaries
Term
If the oval foramen persists, what kind of blood shunting occurs?
Definition
Left to right atrial shunting of blood
Term
Closure of the foramen ovale during fetal life causes what?
Definition
Hypertrophy of the right side of the heart, underdeveloped left heart, death
Term
What causes a common atrium?
Definition
Complete absence of atrial septum
Term
What connects tricuspid and bicuspid valve cusps to papillary muscles?
Definition
Chordae tendineae
Term
Unequal division of the truncus arteriosus may result in Tetralogy of Fallot which is characterized by what?
Definition
Pulmonary stenosis, right ventricular hypertrophy, ventricular septal defect, overriding aorta, results in left to right shunt with cyanosis 
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