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