INTRODUCTION The diaphragm is a curved musculo-fibrous sheet that separates the thoracic from the abdominal cavity. It is pierced by structures that pass between these two regions of the body. It’s the primary muscle of respiration. Its dome shaped and consist of a peripheral muscular part and central tendinous part. The muscular part arises from the margins of the thoracic opening and gets inserted into the central tendon. Its attachments to the thoracic wall are low posteriorly and laterally, but high anteriorly. It is rarely affected by intrinsic diseases It has complex embryological development and its subject to a number of congenital anomalies

1. Dr. NDAYISABA CORNEILLE
CEO of CHG
MBChB,DCM,BCSIT,CCNA
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2. INTRODUCTION
• The diaphragm is a curved musculo-fibrous
sheet that separates the thoracic from the
abdominal cavity.
• It is pierced by structures that pass between
these two regions of the body.
• It’s the primary muscle of respiration.
• Its dome shaped and consist of a peripheral
muscular part and central tendinous part.
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3. CONT’D:
• The muscular part arises from the margins
of the thoracic opening and gets inserted into
the central tendon.
• Its attachments to the thoracic wall are low
posteriorly and laterally, but high anteriorly.
• It is rarely affected by intrinsic diseases
• It has complex embryological development and
its subject to a number of congenital
anomalies
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4. EMBRYOLOGY
• ORGIN IN VERTEBRAL , COSTAL AND SPINAL
ATTACHMENTS FROM WHICH MUSCULAR
FIBERS CURVE UPWARDS AND INWARDS
FROM PERIPHERY TO BE INSERTED INTO THE
FIBROUS SHEET CALLED CENTRAL TENDON
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5. Develops from 4 sources
• Septum transversum
• Pleuroperitoneal membrane
• Medial dorsal portion of primary oesophageal
mesentry
• Marginal ingrowths of the body wall
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8. Septum transversum
• Third week of development.
• Mass of mesoderm situated cranially to
the pericardial cavity
• Contributes to the ventral portion such
as the sternal and costal parts
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9. Pleuroperitoneal membrane
• Is a paired dorso-lateral portion
• Fuses with dorsal mesentry of oesophagus and
dorsal portion of the septum transversum to
complete the partition between thorax &
abdomen.
• Forms the primitive diaphragm at 7th wk of
development.
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10. Medial portion of the diaphragm
• From the medial dorsal portion of primary
oesophageal mesentry.
• Fuses with septum transversum &
pleuroperitoneal membrane.
• Curves of diaphragm – develop from growth
of muscle fibres into the dorsal mesentry of
the oesophagus.
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11. • At 9-12th week, the periphery is
contributed by – the marginal outgrowth
of the body wall.
• these contibutions from thoracic
myotome contain nerve fibers of lower six
or seven intercostal nerves - distribute
the sensory fibers to periphery of
diaphragm.
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12. • At the 5th week, nerve fibers from the
3rd, 4th & 5th cervical segments of spinal
cord grow into septum transversum, via
the pleuropericardial membrane to form
the PHRENIC NERVE
• At the 8th week – the diaphragm is
attached to dorsal body of 1st lumbar
vertebrae, giving rise to the domed
contour character of the diaphragm.
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13. Origin of the diaphragm
• sternal part- arising from the posterior
surface of the xiphoid process.
• costal part arising from the deep surfaces
of the lower six ribs and their costal
cartilages & forms the right & left domes.
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14. • vertebral/lumbar part arising from upper
three lumbar vertebrae; forms the right &
left crura & the arcuate ligaments.
• Crura: The right crura is from the bodies of
first three lumbar vertebrae.
• The left crus, from the bodies of first two
lumbar vertebrae.
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16. • Arcuate ligaments: Lateral to the crura on
both sides.
• Medial arcuate ligament is thickened
upper margin of fascia that covers the
psoas muscle.
• Lateral arcuate ligament is thickened
upper margin of the fascia covering the
quadratus lumborum muscle.
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17. Shape of the Diaphragm
• It is studied as
(a)Central tendon
(b)Right & left crus
(c)Right & left dome
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19. Insertion of the Diaphragm
• The diaphragm is inserted into the central tendon
that is trifoliate (like three leaves).
• On the superior side, the surface of the tendon is
partially fused with the pericardium.
• Some of the muscle fibers of the right crus pass up to
the left and surround the esophageal orifice in a
slinglike loop.
These fibers appear to act as a sphincter and possibly
assist in the prevention of regurgitation of the
stomach contents into the thoracic part of the
esophagus.
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21. Anatomic positions
• After forced expiration the right dome lies
anteriorly with the fourth costal cartilage and
therefore the right nipple, whereas the left
dome lies approximately one rib lower.
• With maximal inspiration, the dome
will descend as much as 10cm, and on a plain
chest radiograph the right dome coincides
with the tip of the sixth rib.
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22. • body is lying on one side, the dependent half
of the diaphragm will be considerably higher
than the uppermost one.
• higher in short, fat people than in tall, thin
people.
• Over inflation of the lung, as occurs for
example in emphysema, causes marked
depression of the diaphragm.
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23. Functions of the Diaphragm
• Muscle of inspiration: On contraction the
diaphragm pulls its central tendon down and
increases the vertical diameter of the thorax.
• The diaphragm is the most important muscle
used in inspiration.
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24. • Muscle of abdominal straining: The
contraction of the diaphragm assists the
contraction of the muscles of the anterior
abdominal wall in raising the intra-abdominal
pressure for micturition, defecation, and
parturition.
• Weight lifting muscle: In a person taking a
deep breath and holding it (fixing the
diaphragm), the diaphragm assists the
muscles of the anterior abdominal wall in
raising the intra-abdominal pressure.
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25. • Thoraco-abdominal pump: The descent of the
diaphragm decreases the intrathoracic pressure &
increases the intra-abdominal pressure.
• This compresses the blood in the inferior vena
cava and forces it upward into the right atrium of
the heart.
• Within the abdominal lymph vessels is also
compressed, and its passage upward within the
thoracic duct is aided by the negative
intrathoracic pressure. The presence of valves
within the thoracic duct prevents backflow.
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26. • three main openings.
• The caval opening lies at the level of the
T8 vertebra in the central tendon.
• It transmits the inferior vena cava and
terminal branches of right phrenic nerve.
Openings in the Diaphragm
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28. • The esophageal opening lies at the level of the
T10 vertebra in a sling of muscle fibers derived
from the right crus at the left of median plane.
• It transmits esophagus, left and right vagus
nerves, esophageal branches of the left gastric
vessels and lymphatics from lower third of the
esophagus.
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30. • The aortic opening lies anterior to the body of
the T12 vertebra between the crura.
• transmits aorta, thoracic duct and azygous
vein.
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31. Other minor opening
• Sympathetic trunk (passes posterior to
the medial arcuate ligament on both
sides).
• Superior epigastric vessels (passes
between the sterna and costal origins of
the diaphragm on each side).
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32. • Left phrenic nerve (pierces the left dome
of diaphragm)
• Neurovascular bundles of lower six intercostal
spaces (passes between the muscular slips of
costal origin of diaphragm)
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33. Vascular supply
• Lower five intercostal and subcostal arteries-
supply the costal margins of the diaphragm
• Phrenic arteries- supply the main central
portion of the diaphragm.
• The phrenic veins follow the corresponding
arteries on the inferior diaphragmatic surface.
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35. Nerve supply of diaphragm
• sensory supply of the central tendon of
diaphragm that is covered by parietal and
peritoneal pleura is from phrenic nerve.
• Sensory supply to the periphery of
diaphragm is from lower six intercostal
nerves.
• The motor nerve supply of diaphragm is only
from the phrenic nerve.
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37. Phrenic nerve
• descends anterior to the pulmonary hilum,
between the fibrous pericardium and mediastinal
pleura, to the diaphragm, accompanied by the
pericardiophrenic vessels.
• It supplies sensory branches to the mediastinal
pleura, fibrous pericardium and parietal serous
pericardium.
• The right phrenic nerve is shorter and more
vertical than the left
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38. END
Dr Ndayisaba Corneille
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By
DR NDAYISABA CORNEILLE
MBChB,DCM,BCSIT,CCNA
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