Anatomy III: Blood and the Cardiovascular and Respiratory Systems

Diaphragm Anatomy

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Anatomy III: Blood and the
Cardiovascular and Respiratory
Systems

Dr. José Luis Monroy Antón

6 CMLesson 7
Diaphragm. Arteries, veins and
nerves of the diaphragm

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Diaphragm Structure

2Diaphragm
· Musculotendinous wall that separates the
thorax and the abdomen

• Shape: double domed tent, convex for the
  thorax and concave for the abdomen.
  Normally the right dome is higher thanks to
  the liver
  It is the main muscle of respiration:

- It participates specially in the inspiration,
when it descends
- It also participates in the expiration, but
it is mostly passive

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Diaphragm Surface and Movement

3Diaphragm
· We can divide its surface into central
and peripheral:

- Central: moving part, it contains the
central tendon of the diaphragm,
attached to the pericardium
- Peripheral: it is firmly attached to
the thoracic cage and the superior
lumbar vertebrae

• During expiration, the diaphragm can
  achieve the level of 5th rib, but it is
  variable due to the posture and the size
  of the abdominal viscera

Central tendon/
right dome
Caval opening
Diaphragm
(right costal part)
11th rib

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Central Tendon of the Diaphragm

4Central tendon of the diaphragm
Anteromedian gap
Xiphoid process of sternum
Sternal part
Sternocostal triangle
(anterolateral gap)
Costal origin
Caval opening
Right costal part
Costal cartilage
Left costal part
Central tendon
Esophageal
hiatus
Median arcuate
ligament
Gap for
psoas
major
Aortic hiatus
Left
crus
Medial arcuate
ligament
Lumbocostal
triangle
Lateral arcuate
ligament
12th rib
12th rib
Lumbar part
Anterior longitudinal
ligament

• The peripheral muscular
  fibers converge radially on
  the central aponeurotic
  part, called central tendon
• Shape of a cloverleaf
  due its three leaves
• It is pierced in the middle
  by the inferior vena cava
• The surrounding muscular
  part forms a continuous
  sheet, but we can divide it
  in three parts based on the
  attachments

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Muscular Portion of the Diaphragm

5
Quadratus lumborum
Right crusMuscular portion of the diaphragm
· Parts of the muscular portion of the diaphragm:

- Sternal part: two muscular fibers that go to the xiphoid
process
- Costal part: it forms the two domes and consists in wide
muscular strips that attach to the inferior six costal cartilages
and their ribs
- Lumbar part: it forms the crura, from the medial and lateral
arcuate ligaments to the three superior lumbar vertebrae

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Diaphragm Crura

6Crura of the diaphragm
· Crura: musculotendinous bands that begin at the bodies of L1, L2, L3
vertebrae and their discs:

- Right crus: larger and longer than the left. From the first three lumbar
vertebrae. It forms the esophageal hiatus
- Left crus: from the first two lumbar vertebrae
· Median arcuate ligament: it is a ligament that unites both crura. It makes an
arch over the anterior aspect of the aorta, forming the aortic hiatus
· Medial arcuate ligament: it is a thickening of the psoas fascia that makes a
hole for the psoas major muscle
· Lateral arcuate ligament: it makes a hole for the quadratus lumborum
muscles. It goes from the L12 transverse process to the tip of the 12th rib

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Arcuate Ligaments and Diaphragm Openings

7REGE CAROLO III-
ANNO
MDCCLXXVIII
Lateral arcuate Medial arcuate
Median arcuate
Aorta
Medial arcuate
Quadratus lumborum
Psoas
Lateral arcuate
Quadratus lumborum
Psoas
Least s.n.
Azygos
Least s.n.
Thoracic duct

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Diaphragm Openings and Structures

8Check in this picture
the right crus forming
the esophageal hole,
even being this hole
located left to the
midline
Check
the arcuate
ligaments
Sternal portion of diaphragm
Ziphoid process
Sternocostal triangle,
also known as Triangle
of Morgagni, or
Triangle of Larrey
Sternocostal triangle
Costal portion of diaphragm
Vena cava
Central tendon
Ribs
Esophagus
within
esophageal
hiatus
Aorta within
aortic hiatus
Celiac trunk
Right crura
Left crura
Lateral arcuate ligament
Quadratus
lumborum
muscle
Medial arcuate ligament
Psoas major muscle
Lumbar spine

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Crura and Arcuate Ligaments

9Check the two crura and the arcuate ligaments
Median arcuate
ligament
Gap for
psoas
major
Aortic hiatus
Right crus
Left
crus
Medial arcuate
ligament
Lumbocostal
triangle
Lateral arcuate
ligament
12th rib
12th rib
Quadratus lumborum
Lumbar part
Anterior longitudinal
ligament

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Central Tendon and Associated Structures

10Central tendon of diaphragm
Bare area of pericardium
Sternal reflection of right pleura
Costomediastinal recess
Internal thoracic vessels
Sternal reflection of left pleura
Transversus thoracis muscle
Fat pad
External oblique
*
Diaphragmatic part
Left phrenic nerve
Right phrenic nerve
Pericardial sac fused
with central tendon
Inferior vena cava
Esophagus
Central tendon
Central tendon
of diaphragm
Thoracic duct
Aorta
Azygos vein
Splanchnic
nerve
Diaphragmatic
part“
Sympathetic
trunk
Costodiaphragmatic
recess
Latissimus dorsi m.
Costal part
*
Serratus posterior
inferior m.
*
of parietal pleura
Superior view
Copyright @ 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins

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Diaphragm Openings Overview

11Holes of the diaphragm
Caval
opening
Sternum
Esophageal
hiatus
T8
Diaphragm
Inferior
vena cava
Aortic
hiatus
T10
Esophagus
Aorta
CT12
Celiac trunk
Superior
mesenteric artery

• Every structure that goes
  from thorax to abdomen,
  must cross through the
  diaphragm
  · We have three large holes
  and some small ones. The
  three large from anterior to
  posterior are:

- Caval
- Esophageal
- Aortic

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Caval Hiatus

12Caval hiatus

• Most anterior and superior hole, at the
  level of T8-T9 vertebrae
• Located in the middle of the central
  tendon of the diaphragm, slightly to the
  right side
  · Structures that pass through the hole
  - Vena cava
  - Lymph vessels from the liver to the
  middle phrenic and mediastinal
  lymph nodes

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Esophageal Hiatus

13Esophageal hiatus
. Oval opening in the right
crus of the
diaphragm, at the level of T10
. The fibers of the right crus cross one another
forming a muscular sphincter that constrict
the esophagus when the diaphragm contracts
· The left crus can contribute to the formation of
the right margin of the hiatus in about 30% of
the people

• Structures that pass through the hole:
  - Esophagus
  - Anterior and posterior vagal trunks
  - Esophageal branches of the left gastric
  vessels
  - Some lymphatic vessels

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Aortic Hiatus

14Aortic hiatus
. Most posterior and inferior hiatus,
level of T12

• Located between the crura and the
  median arcuate ligament
• Respiratory
  movements
  of
  the
  diaphragm do not affect the blood flow
• Structures that pass through the hole:
  - Aorta
  - Thoracic duct
  - Azygos and hemi-azygos when
  they are formed
  below the
  diaphragm

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Other Diaphragm Openings

15Other small openings
· Sternocostal triangle: between the sternal
and costal attachments of the diaphragm
- Lymph vessels from the surface of the
liver
- Superior epigastric arteries and veins

• Space
  behind the medial arcuate
  ligament: for the psoas, the sympathetic
  trunks and the least splanchnic nerves
  . Small hole for the greater splanchnic
  nerve
  · Small hole for the lesser splanchnic nerve

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Diaphragm Actions

16Actions of the diaphragm
· Contraction: pull inferiorly the domes, flatterning the convexity
of the diaphragm
- This descends the abdominal viscera
- This increases the volumen of the thoracic cavity
- This decreases the intrathoracic pressure
- This increases the intraabdominal pressure
- This two games of pressure helps the venous blood to return
to the heart
. Remember that when we say "the descending of the diaphragm",
only the domes descend, because the periphery is attached to
the ribs and their cartilages

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Diaphragm Level Changes with Position

17Level of the diaphragm changes with position
· Trendelenburg position: here the diaphragm
achieves its most superior level because the
abdominal viscera pushes the diaphragm
· Lying to one side: one hemidiaphragm rises to a
more superior level than the other
· Standing: the diaphragm achieves an inferior level.
So, people with dyspnea prefer to sit instead of lie
down

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Arterial Supply of the Diaphragm

18Arterial supply of the diaphragm

• Superior surface:
  - Pericardiacophrenic and musculophrenic arteries,
  branches of the internal thoracic artery
  - Superior phrenic arteries, from the thoracic aorta
• Inferior surface:
  - Inferior phrenic arteries, that can arise from the abdominal
  aorta (in fact, they are its first branches), or from the celiac
  trunk

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Diaphragm Arterial Supply Illustration

19Arterial supply of the diaphragm
Left: superior surface (posterior view). Right: inferior surface (anterior view)

-
Right and left
internal thoracic
arteries
Right inferior phrenic
artery and vein
Thoracic
aorta
Superior phrenic
arteries
Right internal
thoracic vein
Left inferior phrenic
artery and vein
C
Pericardiaco-
phrenic artery
and vein
Thoracic aorta
Heart inside
pericardium
Internal thoracic
artery and vein
Superior phrenic
artery
Right and left domes
of diaphragm
Right and left
superior epigastric
arteries and veins
Right and left
musculophrenic
arteries
and veins
Inferior vena
cava
Abdominal aorta
Suprarenal vein
and artery

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Venous Drainage of the Diaphragm

20Venous drainage

• Superior surface:
  - Pericardiacophrenic and musculophrenic veins, that will end into the internal
  thoracic veins
  - Superior phrenic vein: only in the right side. It will end at the inferior vena cava
  - Some veins from the posterior curvature of the diaphragm drain into the azygos and
  hemi-azygos veins
• Inferior phrenic veins:
  - Right inferior phrenic vein: drains at the IVC
  - Left inferior phrenic vein: double vessel:
  · Anterior branch: passes anterior to the esophageal hiatus to end at the IVC
  · Posterior branch: that ends at the left suprarenal vein

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Diaphragm Venous Drainage Illustration

21Venous drainage of the diaphragm
Left: superior surface (posterior view). Right: inferior surface (anterior view)
Right and left
internal thoracic
arteries
Right internal
thoracic vein
Pericardiaco-
phrenic artery
and vein
Thoracic aorta
Heart inside
pericardium
Internal thoracic
artery and vein
Superior phrenic
artery
Right and left domes
of diaphragm
Right and left
superior epigastric
arteries and veins
Right and left
musculophrenic
arteries
and veins
Right inferior phrenic
artery and vein
Thoracic
aorta
Superior phrenic
arteries
Left inferior phrenic
artery and vein
Inferior vena
cava
Abdominal aorta
Suprarenal vein
and artery

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22