Body Cavities, Mesenteries, And Diaphragm Flashcards
Early int he fourth week of development, the ___ __-the primordium of the body cavities-appears as a horseshoe-shaped cavity
Intraembryonic coelom
The bend in this cavity at the cranial end of the embryo represents the future ___ ___, and its limbs indicate the future pleural and peritoneal cavities
Pericardial cavity
The distal part of each limb of the intraembryonic coelom is continuous with the ___ ___ at the lateral edges of the embryonic disc
Extraembryonic coelom
This communication is important because most of the midgut normally herniated through this communication into the __ ___
Umbilical cord
The intraembryonic coelom provides room for the abdominal organs to __ and ___
Develop
Move
During the embryonic lateral folding, the limbs of the coelom are brought together on the __ aspect of the embryo
Ventral
The ___ ___ becomes the embryonic body cavity, which is divided into three well-defined body cavities during the fourth week: a pericardial cavity, two pericardioperitoneal canals connecting the pericardial and peritoneal cavities, and a large peritoneal cavity.
Intraembryonic coelom
These body cavities are lined by the mesothelium- a parietal wall derived from the ___ ___ and a visceral wall derived from the ___ ___
Somatic mesoderm
Splanchnic mesoderm
The mesothelium forms the major portion of the ___
Peritoneum
The peritoneal cavity is connected to the extraembryonic coelom at the ___
Umbilicus
The peritoneal cavity loses its connection with the extraembryonic coelom during the 10th week as the intestines return to the abdomen from the umbilical cord
Ok
During formation of the head fold, the heart and __ __ are relocated ventrocaudally, anterior to the foregut.
Pericardial cavity
As a result , the pericardial cavity opens into the ___ ___, which pass dorsal to the foregut
Pericardioperitoneal canals
After embryonic folding, the caudal parts of the __, __, and ___ are suspended into the peritoneal cavity from the dorsal abdominal wall by the __ ___
Foregut, midgut, and hindgut
Dorsal mesentery
A mesentery is a double layer of ___ that begins as an extension of the visceral peritoneum that covers an organ
Peritoneum
The mesentery connects the organ to the body wall and conveys its __ and __
Vessels and nerves
Transiently, the dorsal and ventral Mesenteries divide the peritoneal cavity into right and left halves
The ventral mesentery soon disappears, except where it is attached to the caudal part of the foregut
The peritoneal cavity then becomes a continuous space
The peritoneal cavity then becomes a continuous space
The arteries supplying the primordial gut-what are they-pass between the layers of the dorsal mesentery
Celiac arterial trunk
Superior mesenteric artery
Inferior mesenteric artery
Each pericardioperitoneal canal lies ___ to the proximal part of the foregut and __ to the septum transversum
Lateral
Dorsal
What is the septum transversum
A thick plate of mesoderm that occupies the space between the thoracic cavity and the omphaloenteric duct
The septum transversum is the primordium of the central tendon of the ___
Diaphragm
Partitions form in each pericardioperitoneal canal, separating the pericardial cavit from the pleural cavities, and the pleural cavities from the peritoneal cavity
Ok
Because of the growth of the __ ___ into the pericardioperitoneal canals
Bronchial buds
What are the pericardioperitoneal canals
Pair of membranous ridges is produced int he lateral wall of each canal
The cranial ridges-the __ __-are located superior to the developing lungs, and the caudal ridges- the __ __- are located inferior to the lungs
Pleuropericardial folds
Pleuroperitoneal folds
As the pleuropericardial folds enlarge, they form partitions that separate the pericardial cavity fromt he pleural cavities. What are the partitions called
Pleuropericardial membranes
What do pleuropericardial membranes contain
Common cardinal veins , which drain the venous system into the sinus venosus of the primordial heart
Initially the bronchial buds are small relative to the heart and pericardial cavity.
Ok
They grow laterally from the caudal end of the trachea into the ___ ___
Pericardioperitoneal canals
As the primordial pleural cavities expand ventrally around the heart, they extend into the body wall, splitting the mesenchyme into two layers
An outer later that becomes the thoracic wall
An inner layer (pleuropericardial membrane) that becomes the fibrous pericardium, the outer layer of the pericardial sac that encloses the heart
The pleuropericardial membranes project into the cranial ends of the pericardioperitoneal canals
With subsequent growth of the common cardinal veins, positional displacement of the heart and expansion of the pleural cavities , the pleuropericardial membranes become mesentery-like folds extending fromt he lateral thoracic wall
By the seventh week, the pleuropericardial membranes fuse with the mesenchyme ventral to the esophagus, separating the pericardial cavity from the pleural cavities
The primordial mediastinum consists of a mass of mesenchyme that extends from the sternum to the vertebral column, separating the developing lungs
The right pleuropericardial opening closes slightly earlier than the left one and produces a larger __ __-
Pleuropericardial membrane
The pleuroperitoneal folds enlarge, they project into the ___ __
Pericardioperitoneal canals
Gradually, the folds become membranous , forming the ___ ___
Pleuroperitoneal membranes
Eventually, these membranes separate the pleural cavities from the peritoneal cavity.
The pleuroperitoneal membranes are produced as the developing lungs and pleural cavities expand and invade the body wall. They are attached dorsolaterally to the abdominal wall and their crescentic free edges initially project into the caudal ends of the pericardioperitoneal canals
During the 6th week, the pleuroperitoneal membranes extend ventromedial until their free edges fuse with the dorsal mesentery of the esophagus and the __ __
Septum transversum
The pleuroperitoneal membranes separates the pleural cavities from the peritoneal cavity
Closure of. The pleuroperitoneal openings is completed by the migration of myoblasts into the pleuroperitoneal membranes
The pleuroperitoneal opening on the r__side closes slightly before the __ one
Right left
The diaphragm is a
Dome shaped , musculotendinous partition that separates the thoracic and abdominal cavities
The diaphragm develops from four embryonic components
Septum transversum
Pleuroperitoneal membranes
Dorsal mesentery esophagus
Muscular ingrowth from the lateral body walls
This transverse septum , which is composed of mesodermal tissue, is the primordium of the central tendon of the ___
Diaphragm
The septum transversum grows dorsally from the ventrolateral body wall and forms a semicircular shelf that separates the heart from the __
Liver
After the head folds ventrally during the fourth week, the septum transversum forms a thick, incomplete connective tissue partition between the pericardial and abdominal cavities
The septum transversum expands and fuses with the mesenchyme ventral to the esophagus and the pleuroperitoneal membranes
These membranes fuse with the dorsal mesentery of the esophagus and the septum transversum
This fusion completes the partition between the thoracic and abdominal cavities and forms the primordial diaphragm
The pleuroperitoneal membranes represent relatively small portions of the neonates ___
Diaphragm
The septum transversum and pleuroperitoneal membranes fuse with the dorsal mesentery of the ___
Esophagus
During the 9th and 12th weeks, the lungs and pleural cavities enlarge, burrowing into the lateral body walls. During this process , the tissue of the body wall is split into two layers. What are they
External layer that becomes part of the definitive abdominal wall
An internal layer that contributes to the peripheral parts of the diaphragm , external to the parts derived fromt he pleuroperitoneal membranes
Further extension of the developing pleural cavities into the lateral body walls forms the right and left __ ___, establishing the characteristic dome-shaped configuration of the diaphragm
Costodiaphragmetic recesses
During the fourth week of development, the septum transversum lies opposite the third and did the ___ ___
Cervical somites
During the fifth week, myoblasts from these somites migrate into the developing diaphragm, bringing their nerve fibers with them
Ok
Consequently, the __ nerves that supply motor innervation to the diaphragm arise fromt he ventral primary rami of the 3rd, 4th, and 5th cervical spinal nerves, which join together on each side to form a phrenic nerve
Phrenic
The phrenic nerve also supply sensory fibers to the superior and inferior surfaces of the right and left domes of the ___
Diaphragm
Rapid growth of the dorsal part of the embryo;s body results in an ___ ___ of the diaphragm
Apparent descent
By the sixth week, the developing diaphragm is at the level of the __ ___
Thoracic somites
The phrenic nerves now have a __ course
Descending
By the beginning of the _ week, the dorsal part of the diaphragm lies at the level of the first lumbar vertebra
8
The phrenic nerves in the embryo enter the diaphragm by passing through the ___ ___
Pleuropericardial membranes
For this reason, the phrenic nerves subsequently lie on the fibrous pericardium of the heart, which is derived from the pleuropericardial membranes
The costal border of the diaphragm receives sensory fibers from the lower intercostal nerves because of the origin of the peripheral part of the diaphragm from the lateral body walls
Posterolateral defect of the diaphragm is the only relatively common congenital anomaly involving the ___
Diaphragm
Posterolateral diaphragmetic defects occur in 1/3000 neonates ___ ___ ___
Congenital diaphragmatic hernia
What is congenital diaphragmatic hernia
Herniation of abdominal contents into the thoracic cavity
CDH is the most common cause of __ __
Pulmonary hypoplasia
CHD can lead to what
Life threatening respiratory difficulties
If severe lung hypoplasia is present, some primordial alveoli may rupture, casing air to enter the pleural cavity, what is this called
Pneumothorax
What causes unilateral CDH
Defective formation or fusion of the pleuroperitoneal membrane with the other three parts of the diaphragm
CDH produces a large opening in the ___ region of the diaphragm
Posterolateral
If a pleuroperitoneal canal is still open when he intestines return tot he abdomen from the umbilical cord in the _ week, some intestine and other viscera may pass into the thorax and compress the ___
10
Lungs
Often the stomach, spleen, and most of the intestines __ in CHD
Herniate
CHD usually occurs on the _ side and is likely related to the earlier closure of the right pleuroperitoneal opening
Left
In CHD chromosomal abnormalities and gene mutations, including those of the zinc finger factor __, have been implicated in cases of CDH
GATA6
How diagnose prenatal CDH
Ultrasonography and magnetic resonance imaging
Ina. Relatively uncommon condition, __ __, half the diaphragm has defective musculature, causing it to balloon into the thoracic cavity as an aponeurotic sheet, forming a diaphragmatic pouch
Diaphragmatic eventration
Consequently in diaphragmatic eventration, the abdominal viscera are displaced superiorly into the what
The pocket like outpouching of the diaphragm
What causes diaphragmatic eventration
Failure of the muscular tissue from the body wall toe xtend into the pleuroperitoneal membrane on the affected side
What does a retrosternal(parasternal) hernia, herniate through
Sternocostal hiatus
What is the sternocostal hiatus
Opening for the superior epigastric vessels in the retrosternal area
Where is the sternocostal hiatus
Between the sternal and costal parts of the diaphragm
Herniation of the intestine into the pericardial sac may occur or part of the heart may descend into the peritoneal cavity in the __ region
Epigastric
Large birth defects are commonly associated with body wall defects in the ___ region (omphalocele)
Umbilical
