Respiratory System - Diaphragm
Embryology - 14 Jun 2024 Expand to Translate |
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Introduction
The respiratory system does not carry out its physiological function (gas exchange) prenatally and postnatally the lungs continue to grow for another 8+ years. Many other tissues/systems are involved in respiratory function: musculoskeletal (ribs and diaphragm) cardiovascular (pulmonary circulation). The musculoskeletal begins functioning prenatally, the cardiovasular pulmonary circulation is activated and altered postnatally.
The diaphragm along with the ribcage are the musculoskeletal structures that regulate lung inflation. The topic of musculoskeletal development is also covered in a separate set of notes (More? Musculoskeletal System Development).
In humans, the muscles of the diaphragm arise from somite level 3 to 5 (C3 to C5), which also corresponds to the levels of segmental nerves providing innervation of the diaphragm.
Failure of complete diaphragm development can lead to a herniation of abdominal components through channels or gaps in the developing diaphragm into the pleural cavity.
In humans, in the third trimester preparatory fetal respiratory movements occur, which are thought to have a number of roles in late respiratory development.
Some Recent Findings
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More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Diaphragmdevelopment <pubmed limit=5>Diaphragm+development</pubmed> |
Diaphragm Components
Five elements contribute to the diaphragm.
septum transversum - central tendon 3rd to 5th somite - musculature of diaphragm (More? Somitogenesis) ventral pleural sac - connective tissue mesentry of oesophagus - connective tissue around oesophasus and IVC (More? Gastrointestinal Tract Development) pleuroperitoneal membranes - connective tissue around central tendon Pleuroperitoneal FoldThe transient pleuroperitoneal fold (PPF) arise from the posterior body wall, and appears in late week 4 (Carnegie stage 13/14, CRL 6mm) and is present until week 6 (Carnegie stage 17, CRL 14mm).[1] After this time it can no longer be separated from the diaphragm. These pair of folds have a triangular shape and abnormalities in their development is related to congenital diaphragmatic hernia (CDH). Diaphragm Innervation
Fetal Respiratory MovementsFetal respiratory movements (FRM) or Fetal breathing movements (FBM) are thought to be regular muscular contrations occurring in the third trimester, preparing the respiratory muscular system for neonatal function and to also have a role in late lung development. The majority of FBM research has been carried out in fetal sheep.[4] Hypoxia, decreased oxygen levels, blocks these movements by inhibition of the brain stem respiratory centres. Hypercapnia, increased carbon dioxide levels, or acid cerebrospinal fluid perfusion can cause an increase in the regularity and depth of breathing. Hormones also affect fetal breathing movements: inhibitors of prostaglandin synthetase (indomethacin, meclofenamate or aspirin) induce continuous fetal breathing movements, while prostaglandin E2 arrests fetal breathing.
Hypercapnia (Greek, hyper = "above" and kapnos = "smoke") or hypercarbia increased carbon dioxide levels.
AbnormalitiesCongenital Diaphragmatic HerniaInternational Classification of Diseases code Q79.0 Failure of the pleuroperitoneal foramen (foramen of Bochdalek) to close allows viscera into thorax. Intestine, stomach or spleen can enter the pleural cavity, compressing the lung.
Australian national rate (1982-1992) 2.1 - 3.8 /10,000 births.[10]
Adult DiaphragmReferences
Reviews<pubmed></pubmed> <pubmed>22214468</pubmed> <pubmed>18510546</pubmed> <pubmed>18403452</pubmed> <pubmed>16723533</pubmed> <pubmed></pubmed> Articles<pubmed>21370493</pubmed> Search PubMed NowSearch PubMed Now: diaphragm development | phrenic nerve development | fetal respiratory movements | Pubmed - Congenital Diaphragmatic Hernia | OMIM - Congenital Diaphragmatic Hernia Glossary Links
Cite this page: Hill, M.A. (2024, June 14) Embryology Respiratory System - Diaphragm. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Respiratory_System_-_Diaphragm
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