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DIAPHRAGM & PLEURAL CAVITIES
INTRAEMBRYONIC CEOLOM
EMBRYONIC BODY CAVITY
INTRAEMBRYONIC MESODERM
• 3RD WEEK • AXIAL– PRECHORDAL
MESENCHYME– CARDIOGENIC – SEPTUM TRANSVERSUM
• PARAXIAL • INTERMEDIATE• LATERAL PLATE
CEOLOMIC SPACES
• 18th Day • Isolated Small Spaces
In lat. Plate mesoderm• Due To Apoptosis• Primordium Of Intra
Embryonic Ceolom • Cells at periphery of
vesicles,become epithelial.
INTRA EMBRYONIC CEOLOM
• Horse Shoe Shaped Cavity
• Caudally to the level of 1st somite
• No communication between intra and extra embryonic ceolom
INTRA EMBRYONIC CEOLOM• Intraembryonic coelom extends
to caudal wall of the yolk sac. • Distal part of each limb
communicates with the extraembryonic coelom from 4th somite.
• Connection closes during the 10th week
DERIVATIVES INTRA EMBRYONIC CEOLOM
• Midline ventral portion, forms pericardial cavity.
• Pericardioperitoneal canals pleural cavities and the uppermost part of the peritoneal cavity
• Lower part peritoneal cavity• The division is achieved by
development of three sets of partitions – Septum transversum (unpaired)– Pleuropericardial membranes
(paired)– Pleuroperitoneal membranes
(paired
FOLDING4TH WEEK
CRANIO CAUDAL HORIZONTAL
EFFECT OF FOLDING
• Pericardial cavity & heart relocated ventrocaudally, ant. to foregut
• Pericardioperitoneal canals, lateral to proximal part of foregut & dorsal to septum transversum
• The caudal parts turn 90° • Single large cavity• communicate with extraembryonic
coelom ventrally• After embryonic folding, the caudal
part of foregut, midgut, & hindgut are suspended in the peritoneal cavity by the dorsal mesentery
PLEURAL CAVITIES
• LUNG BUDS– 4TH WEEK – VENTRAL WALL OF
FOREGUT
• PERICARDIO PERITONEAL CANALS– PRIMARY PLEURAL
CEOLOM– PLEUROPERICARDIAL
PLEUROPERITONEAL CANALS
DEFINITIVE PLEURAL CAVITIES• PULMONARY RIDGE
– PLEURO PERICARDIAL MEMBRANE • PHRENIC NERVE COMMON
CARDINAL VEIN – PLEURO PERITONEAL MEMBRANES
• INVASION & SPLITTING OF SOMATOPLEURIC MESENCHYME– CRANIALLY
• PLEUROPERICARDIAL MEBRANE– VENTROMEDIALLY
• FIBROUS PERICARDIUM• PARIETAL layer of serous
pericardium• MEDIASTINAL pleura
– DORSOCAUDALLY• Dorsolumbar part of diaphragm
SEPTUM TRANSVERSUM
SEPTUM TRANSVERSUM• 3rd Week
– Axial Mesenchyme– Cranial To Cardiogenic Mesoderm
• 4th Week Folding– B/W Pericardial & Peritoneal Cavities– Partial Separation
• Pars Diaphragmatica– Central Tendon– Sternal & Costal Parts – Myoblast Originating In The Septum Trans. Emigrate Into Pleuroperitoneal
Membrane • Pars Mesenterica
– Median sagittal plane • Pars Intermedia
THORACO ABDOMINAL DIAPHRAGM
MUSCULOTENDINOUS DOME SHAPED PARTITION
DIAPHRAGM
• COMPOSITE STRUCTURE– SEPTUM TRANSVERSUM
• Pars diaphragmatica– Sternal & costal parts
• Pars mesenterica– Gastrohepatic ligament – Anterior to esophageal hiatus
– MESENTARY OF ESOPHAGUS – PLEUROPERITONEAL FOLDS &
MEMBRANES– MESENCHYME OF BODY WALL
• LONG ARM OF Ch 15
MESENTERY OF ESOPHAGUS
• Double Layer Of Peritoneum
• Connecting To Body Wall• Transmits Vessels &
Nerves• Condenstaion Of
Mesenchyme From L1 ---L3
• Muscular Bands– Rt. & Lt Crura Of
Diaphragm
PLEURO PERITONEAL MEMBRANES• 5th Week Pleuroperitoneal
Folds In Pleuro Peritoneal Canals
• Pleuroperitoneal Membrane• 7th Week Fuses With
Mesentery Of Esophagus And Septum Transversum
• Myoblast of Septum Trans. Migrate into PPM Forming bulk of diaphragmatic musculature
• Fetal Vs Newborn Diaphragm• Right Closes Earlier
MESODERMOF BODY WALL• EXPANDING LUNGS
– 9th to 12th weeks, the lungs and pleural cavities "burrow" into lateral body walls
• MESENCHYME OF BODY WALL SPLIT INTO – INNER
• Contributes to peripheral parts of diaphragm, external to parts derived from pleuroperitoneal membranes
– OUTER• becomes part of the definitive abdominal
wall
• Further extension into the lateral body walls forms costodiaphragmatic recesses establishing characteristic dome-shaped configuration of the diaphragm.
MUSCLES OF DIAPHRAGM
• MYOBLAST • TWO SOURCES • MYOBLAST ORIGINATING IN BODY WALL • MYOBLAST ORIGINATING FROM SEPTUM
TRANSVERSUM
POSITIONAL CHANGES
• GROWTH OF DORSAL PART of body • ELONGATION OF NECK• DESECNT OF HEART • ENLARGEMENT OF PLEURAL AND
PERICARDIAL CAVITIES• 4TH WEEK------ CERVICAL SOMITES• 6TH WEEK------ THORACIC• 8TH WEEK ------ LUMBAR
NERVE SUPPLY
PHRENICLOWER SIX INTERCOSTAL NERVES
DIAPHRAGMATIC HERNIA
• Congenital Diaphragmatic Hernia– Most Common– Herniation Of Abdominal
Visceras Lung Hypoplasia– Polyhydramnios – POSTEROLATERAL
– Failure Of Fusion Of Pleuro Peritoneal Membranes
– Uni Or Bilateral– UNILATERAL LEFT (Rt.
Opening Is Smaller And Closes Earlier
• Defects In Septum Transversum
• Parastenal Hernia (Morgagni)– Sternocostal hiatus for sup.
Epigastric vessels – Failure Of Muscular Fiber– Heart into pericardial cavity – Herniation of intestine in
pericardial sac
• Hiatal Hernia– Acquired– Congenital
• Large esophageal hiatus• Short esophagus
• Eventration of diaphragm– Failure of muscular
tissue from body wall to extend into pleuroperitoneal mebrane
• Gastroschisis– Defective fusion of
lateral body wall– Intestine herniate into
abdominal cavity
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