Chapter 7 Flashcards
During the third and fourth weeks, the top layer (ectoderm) of the trilaminar embryonicdisc forms the neural plate that rolls up into a tube to form the brain and spinal cord by the process called ____
neurulation
The visceral layer rolls ventrally and is intimately connected to the gut tube; the parietal layer, together with the overlying ectoderm, forms the ____ (one on each side of the embryo), which move ventrally and meet in the midline to close the ventral body wall
lateral body wall folds
The visceral layer rolls ventrally and is intimately connected to the gut tube; the parietal layer, together with the overlying ectoderm, forms the lateral body wall folds (one on each side of the embryo), which move ventrally and meet in the midline to close the ____
ventral body wall
The space between visceral and parietal layers of lateral plate mesoderm is the ___, which at this early stage is a continuous cavity, because it has not yet been subdivided into the pericardial, pleural, and abdominopelvic regions
primitive body cavity
At the end of the third week, ___ differentiates into paraxial mesoderm, which forms somitomeres and somites that play a major role in forming the skull and vertebrae; intermediate mesoderm, which contributes to the urogenital system; and lateral plate mesoderm, which is involved in forming the body cavity
intraembryonic mesoderm
At the end of the third week, intraembryonic mesoderm differentiates into ____, which forms somitomeres and somites that play a major role in forming the skull and vertebrae; intermediate mesoderm, which contributes to the urogenital system; and lateral plate mesoderm, which is involved in forming the body cavity
paraxial mesoderm
At the end of the third week, intraembryonic mesoderm differentiates into paraxial mesoderm, which forms somitomeres and somites that play a major role in forming the skull and vertebrae; ____, which contributes to the urogenital system; and lateral plate mesoderm, which is involved in forming the body cavity
intermediate mesoderm
Soon after it forms as a solid mesodermal layer, clefts appear in the lateral plate mesoderm that coalesce to split the solid layer into two:
(1) the____ adjacent to the surface ectoderm and continuous with the extraembryonic parietal mesoderm layer over the amnion. Together, the parietal (somatic) layer of lateral plate mesoderm and overlying ectoderm are called the ______;
(2) the _____ layer adjacent to endoderm forming the gut tube and continuous with the visceral layer of extraembryonic mesoderm covering the yolk sac
parietal (somatic) layer - somatopleure
Visceral (splanchnic)
At the end of the third week, intraembryonic mesoderm differentiates into paraxial mesoderm, which forms somitomeres and somites that play a major role in forming the skull and vertebrae; intermediate mesoderm, which contributes to the urogenital system; and _____, which is involved in forming the body cavity
lateral plate mesoderm
Together, the visceral (splanchnic) layer of lateral plate mesoderm and underlying endoderm are called the ___
splanchnopleure
The space created between the two layers of lateral plate mesoderm constitute the ___
primitive body cavity
During the fourth week, the sides of the embryo begin to grow ventrally forming two ___
lateral body wall folds
Similarly, closure of the gut tube is complete except for a connection from the midgut region to the yolk sac called the ___
Vitelline (yolk sac) duct
This closure is aided by growth of the head and tail regions (folds) that cause the embryo to curve into the ___
fetal position
Some cells of the parietal layer of lateral plate mesoderm lining the body wall of the primitive embryonic cavity become mesothelial and form the _____ lining the outside of the peritoneal, pleural, and pericardial cavities
parietal layer of the serous membranes
Some cells of the parietal layer of lateral plate mesoderm lining the body wall of the primitive embryonic cavity become mesothelial and form the parietal layer of the serous membranes lining the outside of the ____, ____, and ___
peritoneal, pleural, and pericardial cavities
In a similar manner, some cells of the visceral layer of lateral plate mesoderm form the ____ covering the abdominal organs, lungs, and heart
Visceral layer of the serous membranes
Visceral and parietal layers are continuous with each other as the ____, which suspends the gut tube from the posterior body wall into the peritoneal cavity
dorsal mesentery
_____ exists only from the caudal foregut to the upper portion of the duodenum and results from thinning of mesoderm of the septum transversum, a block of mesoderm that forms connective tissue in the liver and forms a scaffold for formation of the diaphragm
Ventral mesentery
Ventral mesentery exists only from the caudal foregut to the upper portion of the duodenum and results from thinning of mesoderm of the ____, a block of mesoderm that forms connective tissue in the liver and forms a scaffold for formation of the diaphragm
septum transversum
These mesenteries are ____ of peritoneum that provide a pathway for blood vessels, nerves, and lymphatics to the organs
double layers
___ occur in the thorax, abdomen, and pelvis and involve the heart [ectopia cordis], abdominal viscera [gastroschisis], and/or urogenital organs bladder or cloacal exstrophy], depending on the location and size of the abnormality
Ventral body wall defects
Ventral body wall defects occur in the thorax,
abdomen, and pelvis and involve the heart [_____], abdominal viscera [gastroschisis], and/or urogenital organs bladder or cloacal exstrophy], depending on the location and size of the abnormality
ectopia cordis
Ventral body wall defects occur in the thorax,
abdomen, and pelvis and involve the heart [ectopia cordis], abdominal viscera [____], and/or urogenital organs bladder or cloacal exstrophy], depending on the location and size of the abnormality
gastroschisis
Ventral body wall defects occur in the thorax,
abdomen, and pelvis and involve the heart [ectopia cordis], abdominal viscera [gastroschisis], and/or urogenital organs ______], depending on the location and size of the abnormality
bladder or cloacal exstrophy
____ occurs when lateral body wall folds fail to close the midline in the thoracic region causing the heart to lie outside the body cavity
Ectopia cordis
Sometimes, the closure defect begins at the caudal end of the sternum and extends into the upper abdomen resulting in a spectrum of abnormalities called ____
Cantrell pentalogy
____ occurs when body wall closure fails in the abdominal region
Gastroschisis
____ results from abnormal body wall closure in the pelvic region
Bladder or cloacal exstrophy
___ represents another ventral body wall defect, but it does not arise from a failure in body wall closure
Omphalocele
Instead, it originates when portions of the gut tube [the midgut] that normally herniates into the umbilical cord during the 6th to the 10th weeks [_____] fails to return to the abdominal cavity
physiological umbilical herniation
The ___ is a thick plate of mesodermal tissue occupying the space between the thoracic cavity and the stalk of the yolk sac
septum transversum
This septum does not separate the thoracic and abdominal cavities completely but leaves large openings, the ___, on each side of the foregut
pericardioperitoneal canals
Ventral and lateral expansion is posterior to the ____
pleuropericardial folds
With expansion of the lungs, mesoderm of the body wall forms two components:
(1) the definitive wall of the thorax
(2) the pleuropericardial membranes, which are extensions of the pleuropericardial folds that contain the ___ and ____
common cardinal veins and phrenic nerves
With expansion of the lungs, mesoderm of the body wall forms two components:
(1) the definitive wall of the thorax
(2) the _____, which are extensions of the pleuropericardial folds that contain the common cardinal veins and phrenic nerves
pleuropericardial membranes
Finally, they fuse with each other and with the root of the lungs, and the thoracic cavity is divided into the definitive ___ and two ____
pericardial cavity - pleural cavities
In the adult, the pleuropericardial membranes form the ____
fibrous pericardium
Although the pleural cavities are separate from the pericardial cavity, they remain in open communication with the abdominal (peritoneal) cavity by way of the ____
pericardioperitoneal canals
During further development, the opening between the prospective pleural and peritoneal cavities is partially closed by
crescent-shaped folds, the ___, which project into the caudal end of the pericardioperitoneal canals
pleuroperitoneal folds
By the seventh week, the folds become thinner to form the ____ that grow medially to fuse with the mesentery of the esophagus that forms the crura of the diaphragm around the aorta
pleuroperitoneal membranes
By the seventh week, the folds become thinner to form the pleuroperitoneal membranes that grow medially to fuse with the mesentery of the esophagus that forms the ___ around the aorta
crura of the diaphragm
The central region of these fused membranes forms the _____, whereas their periphery forms connective tissue that serves as a scaffold and guide
for migrating myoblasts
central tendon of the diaphragm
These muscle cells originate from ___ to form the musculature of the diaphragm
cervical segments three to five (C3—C5)
A ___, one of the more common malformations in the newborn [1/2,000], may be caused by shortness of the foregut that keeps the stomach in the thoracic region
congenital diaphragmatic hernia
Innervation of the diaphragm is via the ___ that are derived from ventral primary rami of spinal nerves carrying motor and sensory fibers that also originate from C3 to C5
phrenic nerves
In summary, the diaphragm is derived from
the following structures:
1. The two pleuroperitoneal membranes form the central tendon of the diaphragm and provide a connective tissue scaffold for muscle cells migrating in on the periphery.
2. Muscular components from somites at cervical segments three to five
3. The mesentery of the esophagus, in which the ___ of the diaphragm develop
crura
Frequently, these smaller hernias arise in the ___ and a small peritoneal sac containing intestinal loops may enter the chest between the sternal and costal portions of the diaphragm
parasternal region
” Mesoderm holds the tubes together, and the lateral plate mesoderm splits to form a ____ associated with the gut and a parietal (somatic) layer that, together with overlying ectoderm, forms the lateral body wall folds
visceral (splanchnic) layer
Another type of smaller diaphragmatic hernia, an ____, is thought to be due to congenital shortness of the gut tube in the region of the lower esophagus
esophageal hernia
” Mesoderm holds the tubes together, and the ____ splits to form a visceral (splanchnic) layer associated with the gut and a parietal (somatic) layer that, together with overlying ectoderm, forms the lateral body wall folds
lateral plate mesoderm
” Mesoderm holds the tubes together, and the lateral plate mesoderm splits to form a visceral (splanchnic) layer associated with the gut and a parietal (somatic) layer that, together with overlying ectoderm, forms the ____
lateral body wall folds
” Mesoderm holds the tubes together, and the lateral plate mesoderm splits to form a visceral (splanchnic) layer associated with the gut and a ___ that, together with overlying ectoderm, forms the lateral body wall folds
parietal (somatic) layer
