Thoracic Development

Question 1

Pleural cavities

Answer 1

space in which lungs develop and persist

Question 2

Pericardial cavity

Answer 2

space in which heart develops and persists

Question 3

Peritoneal cavity

Answer 3

space in which abdominal viscera develops and persists

Question 4

Septum Transversum

Answer 4

will become the central tendon of the thoracic diaphragm

Question 5

Intraembryonic Coelom

Answer 5

primordium of embryonic body cavities - develops during 4th week
Horseshoe shaped cavity develops in the lateral mesoderm

Question 6

Cranial end

Answer 6

future pericardial cavity

embryo undergoes head-fold, bringing pericardium and heart venterocaudally

Question 7

Caudal limbs

Answer 7

future pleural and peritoneal cavities

fold in horizontal plane bringing two caudal limbs together - fuse to form peritoneal cavity (lateral folds)

Question 8

Ectopia cordis

Answer 8

cranial fold needs to be finished before lateral folds or heart will be outside the body wall
Sternum never develops

Question 9

Mesenteries

Answer 9

gut tube

double layer of peritoneum that extends from abdominal wall, divides peritoneal cavity into right and left halves

Question 10

Dorsal Mesentery

Answer 10

Permanent Structure

Provides route for vasculature, nerves, and lymphatics to developing organs

Question 11

Ventral Mesentery

Answer 11

remains attached to caudal part of foregut (suspends primordial liver, stomach, and proximal part of duodenum) - becomes falciform ligament and lesser omentum and visceral peritoneum surrounding liver

Question 12

Parietal peritoneum

Answer 12

covers body wall

Question 13

Visceral peritoneum

Answer 13

covers organ

Question 14

Pericardioperitoneal canals

Answer 14

term for intraembryonic coelom after folding of embryo
lies lateral to foregut
dorsal to septum transersum
partitions form in each canal due to developing bronchial buds

Question 15

Pleuropericardial folds (cranial ridges)

Answer 15

Located superior to developing lungs
Separate pleural from pericardial cavities - divides lung from pericardial space
Phrenic nerve gets caught in these folds

Question 16

Pleuroperitoneal folds (caudal ridges)

Answer 16

Located inferior to developing lungs
Separate pleural from peritoneal cavities
become part of diaphragm
Doesn’t fuse in center - right closes first, then left

Question 17

Pleuropericardial membranes

Answer 17

enlargement of pleuropericardial folds becomes partition that separates pleural from periardial cavities
contains common cardinal veins and phrenic nerves

Question 18

common cardinal veins

Answer 18

drain primordial venous system into sinus venosus of primordial heart

Question 19

Pleuropericardial membrane becomes the

Answer 19

fibrous pericardium, comes from body wall (somatic mesoderm) - inner layer

Question 20

primordial mediastinum

Answer 20

forms after 7th week, after pleuropericardial membranes have fused with the ventral mesenchyme
contains all organs of thoracic cavity except lung and the pleura

Question 21

Pleuroperitoneal membranes

Answer 21

enlargement of pleuroperitoneal folds becomes partition that separates pleural from peritoneal cavities
forms posterior portion of diaphragm
During 6th week, these membranes extend ventromedially and fuse with dorsal mesentery of esophagus and septum transversum

Question 22

Diaphragm develops from

Answer 22

septum transversum
pleuroperitoneal membranes
dorsal mesentery of esophagus
muscular ingrowth from lateral body walls

Question 23

what vessels are caught in lateral body wall folds

Answer 23

esophagus, aorta, IVC - run through developed diaphragm

Question 24

Diaphragm is innervated by

Answer 24

phrenic nerve - C 3,4,5

Question 25

Closure of pleuroperitoneal cavities are assisted by

Answer 25

migration of myoblasts into pleuroperitoneal membrane - also aids in innervation (myoblasts migrate from 3-5 cervical myotomes and carry their nerves with them)

Question 26

Posterolateral defect

Answer 26

intestines in lung space - looks like gas/space on radiogram
left side that closes 2nd never fuses
intestines crush lungs

Question 27

Congenital hiatal hernia

Answer 27

protrusion of upper part of stomach into thorax through tear or weakness in diaphragm