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eve opmen o o y av y ap ragm

Diaphragm

Fibromuscular septum separate thoracic cavity from abdominal cavity Parts

y  Central tendon

y  Greater muscular

y  Right crus & Left crus

Superior & Inferior surfaces are covered by serous membranes 

Development of Mesodermal Germ Layer

At beginning of 3rd

week of development, the intra-embryonic mesoderm is

differentiated into

y  Paraxial mesoderm (PAM)

y  Intermediate mesoderm (In M)

y  Lateral plate mesoderm (LP M)

Formation of Intraembryonic Cavity

At the end of 3rd

week, intercellular clefts appear in lateral plate mesoderm on

each side of the midline

When the spaces fuse, the intraembryonic cavity (body cavity) is formed

Cavity is bordered by

y  Somatic mesoderm

y  Splanchnic mesoderm

Folding of Embryo

2 types of folding in embryo

y  Cephalocaudal folding (head to tail fold)

y  Lateral folding

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Development of Diaphragm

Diaphragm develops from 4 components

y  Septum transversum central tendon 

y  2 Pleuroperitoneal membranes

y  Lateral & Dorsal body wall muscular part 

y  Dorsal mesentery of esophagus right & left crus 

Growth of lung buds in pericardioperitoneal canals

Development of Diaphragm

Positional changes & Innervation of Diaphragm

During 4th

Week During 5th

Week By 6th

Week

Septum transversum

(prior to its descent

with the heart) lies

opposite the 3rd

5th

 

cervical somites 

Myoblasts from these

somites migrate into

developing diaphragm

bringing their nerve

(eg. Phrenic nerves)

Apparent descent of 

diaphragm occur at

level of thoracic somites

Phrenic nerve moves

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Diaphragmatic Hernias

Foramen of Morgagni (retrosternal or parasternal hernia)

Herniation through sternocostal hiatus (opening for superior epigastric vessels

in retrosternal area) may occur

Congenital Diaphragmatic Hernia (CDH)

Most frequently caused by failure of 1 or both of pleuroperitoneal membranes

to close the pericardioperitoneal canals.

85-90% cases Hernia is on the left side

Intestinal loops, stomach, spleen, part of liver may enter thoracic cavity

Cause hypoplastic lungs & heart

Most common cause of Pulmonary Hypoplasia 

Figure A Figure B

Hernia is on the left side

Stomach & Bowel are herniated

Hernia is on left side but

underneath, the liver is herniated

into left chest cavity

Polyhydramnios may also present

Also known as Foramen of Bochalek (clinically)

Diaphragmatic Hernias

Esophageal Hernia

Due to congenital shortness of esophagus

Upper portions of stomach are retained in thorax

Stomach is constricted at level of diaphragm

Eventration of Diaphragm

Uncommon condition

Half of diaphragm has defective musculature 

Balloons into thoracic cavity as aponeurotic sheet

Form Diaphragmatic pouch 

Failure of muscle tissue from body wall to extend into pleuroperitoneal

membraneSuperior displacement of abdominal viscera into pouch

Congenital Hiatal Hernia

Herniation of fetal stomach through excessively large esophageal hiatus

(opening through which esophagus & vagus nerve pass)

Uncommon congenital defect

(acquired lesion occur during adult)