This slideshow will give you the understanding of mediastinum and also the structure of heart and lungs

1. By Hermizan Halihanafiah

2. Mediastinum
The central part of the thoracic cavity called mediastinum.
It is between the lungs, extending from the sternum to
the vertebral column, and from neck to the diaphragm
muscle.
Mediastinum contain all thoracic viscera except the lungs
itself.
Among the structure in the mediastinum are the heart,
esophagus, trachea, thymus and several large blood
vessels.

3. Mediastinum can divide in 2
portion:
an upper portion, above the
upper level of the
pericardium, which is
named the superior
mediastinum with its
superior limit at the
superior thoracic opening
and its inferior limit at the
plane from the sternal angle
to the intervertebral disc of
T4-T5 (Plane of Ludwig);

4. Lower portion, below the upper level of the
pericardium. This lower portion is again subdivided
into three parts:
that in front of the pericardium, the anterior
mediastinum
that containing the pericardium and its contents, the
middle mediastinum
and that behind the pericardium, the posterior
mediastinum

5. Lower Portion

6. It is surrounded by the chest wall anteriorly, the
lungs laterally and the spine posteriorly. It is
continuous with the loose connective tissue of the
neck, and extends inferiorly onto the diaphragm.

7. Boundaries of the superior
mediastinum (1)are:
anterior - manubrium of the
sternum
posterior - anterior surface of
bodies of vertebrae T1 through
T4
superior - plane of the thoracic
inlet
inferior - plane of the sternal
angle
lateral - mediastinal pleura

8. Superior Mediastinum
The superior
mediastinum is that
portion of the which
lies between the
manubrium of sternum
anteriorly, and the
upper thoracic
vertebrae posteriorly.

9. Superior Mediastinum
This image shows the
structures of the superior
mediastinum in tact.
Then we will start from
the anterior boundary and
work our way through the
superior mediastinum
from anterior to posterior.

10. With the thorax in tact,
the first thing you see
when you get ready to
study the superior
mediastinum is the
manubrium of the
sternum and the cartilage
of the first rib.
These structures make up
the anterior boundary.

11. The first plane is the
glandular plane. The
gland is what is left of
the thymus.
It consists of two lobes
and is mainly fat in the
adult with small islets
of active thymic cells
scattered throughout.

12. The second plane is the
venous plane and consists
of the:
left brachiocephalic vein
right brachiocephalic
vein
superior vena cava
Intercostal vein
arch of the azygos vein

13. The third plane is the arterial-nervous
plane and consists of
the:
aortic arch and its branches
brachiocephalic artery
left common carotid artery
left subclavian artery
nerves include the:
Left Common Carotid Artery
Phrenic Nerve
Vagus Nerve
left and right vagus nerves
left and right phrenic
nerves Arch Of Aorta
Brachiocephalic Artery
Left
Subclavian
Artery

14. The fourth plane is the
visceral plane and
includes the:
trachea
esophagus
left recurrent laryngeal
nerve
(larynx nerve)

15. The fourth plane is the
visceral plane and
includes the:
trachea
esophagus
left recurrent laryngeal
nerve

16. The fifth plane is the
lymphatic plane and
consists of the:
thoracic duct

17. muscles
origins of the
Sternohyoid and
Sternothyroid
lower ends of the
Longus coli

18. Anterior Mediastinum
The anterior
mediastinum exists
only on the left side
where the left pleura
diverges from the mid-sternal
line.
It is narrow, above, but
widens out a little
below.

19. Boundaries
It is bounded:
in front by the sternum
laterally by the pleurae
posteriorly by the pericardium
anteriorly by the left Transversus thoracis and the
fifth, sixth, and seventh left costal cartilages

21. Contents
It contains:
a quantity of loose areolar tissue
some lymphatic vessels which ascend from the
convex surface of the liver
two or three anterior mediastinal lymph glands
the small mediastinal branches of the internal
thoracic artery

22. Middle Mediastinum
The middle
mediastinum is the
broadest part of the
interpleural space. It is
made up of the
pericardial sac and its
contents.

23. Contents
It contains:
the heart enclosed in the pericardium
the ascending aorta
the lower half of the superior vena cava with the azygos
vein opening into it
the bifurcation of the trachea and the two bronchi
the pulmonary artery dividing into its two branches
the right and left pulmonary veins
the phrenic nerves
some bronchial lymphatic glands

25. Posterior Mediastinum
The posterior
mediastinum is an
irregular triangular
space running parallel
with the vertebral
column.

26. Boundaries
It is bounded:
anteriorally by the pericardium (in front of)
inferiorally by the thoracic surface of the diaphragm
(below).
superiorally by the transverse thoracic plane (above).
This plane is marked by an imaginary line travelling
through the manubriosternal joint to the dividing line
between the fourth and fifth thoracic vertebrae.

27. Boundaries
posteriorally by the bodies of the vertebral column
from the lower border of the fourth to the twelfth
thoracic vertebra (behind).
laterally: by the mediastinal pleura (on either side)

28. Contents
artery
thoracic part of the descending aorta
veins
azygos vein
the hemiazygos vein and the accessory hemiazygos vein
nerves
vagus nerve
splanchnic nerves (Sympathetic nerve)
esophagus
thoracic duct
some lymph glands

29. After the heart has been
removed, you will see the cut
borders of the major vessels
entering and leaving the heart.
The oblique pericardial sinus is
clearly seen within the four
pulmonary veins and inferior
vena cava at this point.
The arrow at the top represents
the division between the
superior mediastinum above
and the inferior mediastinum
below.

30. In Level 2, the pericardium has been removed and the
esophagus can seen along with its plexus derived from
the left and right vagus nerves as well as branches
from the sympathetic chain.
As the esophagus passes through the diaphragm to
enter the abdomen, the left vagus emerges from the
plexus as the anterior vagal trunk and the right vagus
becomes the posterior vagal trunk.

31. You can also see that
the trachea splits into
the right and left
primary bronchi at the
level of the junction
between the superior
and inferior
mediastinum .

32. Once the esophagus has
been studied, the next level
to check out is the thoracic
aorta.
The thoracic aorta starts at
the T4-T5 junction and
extends the full length of
the posterior mediastinum
passing through the aortic
hiatus of the diaphragm
into the abdomen.

33. The thoracic aorta gives
rise to the posterior
intercostal arteries
which pass posterior and
lateral to join the posterior
intercostal veins and
intercostal nerves to form
the neurovascular bundle
That travels along the
inferior border of a rib or
the upper aspect of an
intercostal space.

34.  It also gives rise to
bronchial branches that
enter the root of the lung
to supply the bronchi and
lung tissue.

35. Alongside and behind the
thoracic duct, you will
find the veins that drain
the walls of the thorax,
the azygos and
hemiazygos veins.
Each of these veins begin
in the abdomen as the
ascending lumbar veins.
The ascending lumbar
veins drain parts of the
posterior abdominal wall.

36. The next structures in the
posterior mediastinum
would be the splanchnic
nerves, specifically the
greater splanchnic nerves.
These nerves are derived
from the sympathetic
chains, thoracic ganglion
T5 to T10.
There is also lesser
splanchnic nerves that are
derived from ganglion T10
and T11.

37. The most posterior item in
the posterior mediastinum
is the anterior longitudinal
ligament which
completely covers the
anterior surfaces of the
bodies of the vertebrae.
This extends from the
sacral part of the vertebral
column all the up to the
skull.

38. Heart
Cone shaped
12 cm long, 9 cm wide, 6 cm thick
Mass average 250 g in adult females, 300 g in adult
males
Rest at diaphragm, near the midline of the thoracic
cavity.
Lies in the middle mediastinum.
2/3 of the mass of the heart lies to the left of the body
midline.

40. The pointed end of the heart is the apex.
Apex – directed anteriorly, inferiorly and to the left.
The broad portion of the heart opposite the apex is
the base.
Base – directed posteriorly, superiorly and to the
right.

41. Anterior surface (sternocostal surface) is deep to the
sternum and ribs.
The inferior surface is the part of the heart between
the apex and right border and rests mostly on the
diaphragm.
The right border faces the right lung and extends
from the inferior surface to the base.

44. Also note the three
borders of the heart:
right border (1) made up
of the right atrium
inferior border (2) made
up of right atrium, right
ventricle and left
ventricle
left border (3) made up of
the left ventricle

45. The left border, also
called the pulmonary
border, faces the left
lung and extends from
the base to the apex.

46. Note that the anterior surface shows parts of each of
the four chambers of the heart:
right atrium (RA)
left atrium (LA)
right ventricle (RV)
left ventricle (LV)

47. Coronary Sulcus
When the vessels are removed from the heart, certain
sulci (grooves) can be seen and separated the various
chambers of the heart.
From the anterior view of the heart, the anterior
interventricular and coronary sulci can be seen (the darker
brown areas).
The anterior interventricular sulcus separates the right
and left ventricles.
The anterior part of the coronary sulcus separates the
right atrium from the right ventricle.

48. Coronary Sulcus

49. From the posterior view of the heart, the posterior part
of the coronary sulcus and the posterior
interventricular sulcus can be seen.
 From this view, the coronary sulcus can be seen to
separate the left and right atria from the left and right
ventricles.
The posterior interventricular sulcus separated the
right ventricle from the left ventricle and if followed
inferiorly, it can be seen to be almost continuous with
the anterior interventricular sulcus.

50. Coronary Sulcus

51. Pericardium
Membrane that surround and protect the heart
Confine the heart into its position in the
mediastinum.
Allowing sufficient freedom and movement
vigorous and rapid contraction.
Consists 2 layers; superficial fibrous pericardium
and deeper serous pericardium.

53. Superficial Fibrous Pericardium
Superficial fibrous pericardium is a tough, inelastic,
dense irregular connective tissue.
Resembles bag that rest on and attaches to the
diaphragm.
Prevents overstretching, provide protection and
anchors the heart in the mediastinum.

54. Deeper Serous Pericardium
Thinner, more delicate membrane, forms a double
layer around the heart.
Outer layer is a parietal layer
Inner layer is a visceral layer @ epicardium
Between parietal and visceral layer – pericardial
cavity
Pericardial cavity contain pericardial fluid
Pericardial fluid – reduce friction between 2
membranes as the heart move.

55. Pericardium

56. Layers of the Heart Wall
Epicardium (external)
Myocardium (middle)
Endocardium (internal)

57. Epicardium
@ visceral layer of the
serous pericardium
Thin, transparent
Smooth, slippery texture
to the outermost surface of
the heart.

58. Myocardium Cardiac muscle tissue
Makes up the bulk of
the heart.
Responsible for its
pumping action.
Involuntary

59. Endocardium Innermost
Thin layer
Provide smooth lining
for the chambers of the
heart and covers the
heart valves.

60. Chambers of the Heart
Right atrium
Right ventricle
Left atrium
Left ventricle

62. Right Atrium
Receive blood from superior and inferior vena
kava, and coronary sinus.
Anterior and posterior walls within the right
atrium is differ.
Posterior walls is smooth, anterior wall is rough
due to the presence of muscular ridges called
pectinate muscles.
Between the right and left atrium is a thin
partition called interatrial septum.

63. Right Atrium
A prominent feature of this septum is an oval
depression called the fossa ovalis.
Blood passes from the right atrium to the right
ventricle through tricuspid valve.

65. Right Ventricle
Forms most of the anterior surface of the heart.
Inside – contains a series of ridges formed by raised of
cardiac muscles fibers called trabeculae carneae.
The cusps of tricuspid valve are connected to
tendonlike cords, called chordae tendineae.
Chordae tendineae connected to cone-shaped
trabeculae carneae called papillary muscles.

66. The right ventricle separate from left ventricle by a
partition called interventricular septum.
Blood passes from right ventricle through the
pulmonary valve into a large artery called pulmonary
trunk
Pulmonary trunk will divide into left and right
pulmonary arteries.

67. Left Atrium
Forms most of the base of the heart
Receive blood from 4 pulmonary veins.
Inside the left atrium; anterior and posterior wall
also is smooth.
Blood passes from the left atrium to the left ventricle
through bicuspid (mitral) valve.

68. Left Ventricle
Forms apex of the heart
Contain trabeculae carneae and has chordae
tendineae that anchor the cusps of the bicuspid valve
to papillary muscles.
Blood passes from left atrium through aortic valve
into the largest artery, arch of aorta.
Some blood in the aorta flows into the coronary
arteries, which branch from the ascending aorta and
carry blood to the heart wall.

69. Nerve Supply
The strength and frequency of the
heart beat is controlled by the
autonomic nervous system. Both
parasympathetic and sympathetic
parts of the autonomic nervous
system are involved in the control
of the heart.
The sympathetic fibers arise from
segments T2-T4 of the spinal cord
and are distributed through the
middle cervical and cervico-thoracic
(or stellate) ganglia and the first
four ganglia of the thoracic
sympathetic chain.

70. The sympathetic fibers pass into the cardiac plexus
and from there to the SA node and the cardiac
muscle.
The effect of the sympathetic nerves at the SA node is
an increase in heart rate.
The effect on the muscle is an increase in rise of
pressure within the ventricle, thus increasing stroke
volume

71. The vagus provides the
parasympathetic control to the
heart.
The effect of the vagus at the
SA node is the opposite of the
sympathetic nerves, it decreases
the heart rate.
It also decreases the excitability
of the junctional tissue around
the AV node and this results in
slower transmission.
Strong vagal stimulation here
may produce AV block

72. Conduction System
The heart also has an internal
nervous system made up of the
SA (sinuatrial node) and the
AV (atrioventricular) node.
The AV bundle (His) leaves
the AV node near the lower
part of the interatrial septum
and splits over the upper part
of the interventricular septum
into a left bundle branch (LBB)
and a right bundle branch
(RBB).
Then impuls will send to the
Purkinje Fibers – ventricle
contraction

75. Systemic Circulation
The systemic circulation
includes the flow of
oxygenated blood from the
heart to the tissues in all parts
of the body and the return of
deoxygenated blood back to
the heart.

76. The blood vessels, including
the arteries, capillaries, and
veins, are the main parts of
systemic circulation.

77. Through systemic circulation, oxygen and nutrients
are delivered to the body tissues via the arteries.
Blood is filtered during systemic circulation by the
kidneys (most of the waste) and liver (sugars).

79. The systemic circulatory system
is complex and its functions vary.
The systemic circulatory system
is divided into subsystems for
particular regions of the body.

80. Jugular Vein
Pulmonary Artery
Superior Vena Kava
Inferior Vena Kava
Hepatic vein
Hepatic Portal Vein
Renal Vein
Carotid Artery
Pulmonary Artery
Aorta
Mesentric Artery
Renal Artery
Iliac Artery
IliacVein

82. CORONARY CIRCULATION

83. Coronary Circulation
Nutrient could not diffuse quickly enough from
blood in the chambers of the heart to supply all
layers of cells that make up the heart wall.
For this reason, the myocardium has its own blood
vessels called coronary circulation.
Consists coronary arteries and coronary veins.

84. Coronary Arteries
2 coronary arteries, the right and left coronary
arteries, branch from the ascending aorta and supply
oxygenated blood to myocardium.
The left coronary artery passes inferior and devide
into anterior inventricular branch (left anterior
decending artery) and circumflex branches.

85. Anterior interventricular branch supply oxygenated
blood to the walls of ventricles.
The circumflex branch distributes oxygenated blood
to the walls of the left ventricle and left atrium.

87. The right coronary artery gives off small atrial
branches that supply the right atrium.
Then its continues inferiorly and divide into
posterior interventricular branch and marginal
branch.
Posterior interventricular branch supplies the walls
of 2 ventricles with oxygenated blood.

88. The right marginal branch carries oxygenated blood
to the myocardium of the right ventricle.

89. Figure 19.11b

90. Coronary Veins
After blood passes through coronary arteries, it
flows into capillaries, where it delivers oxygen and
nutrient and collect CO2 and waste product into
veins.
The deoxygenated blood then drains into a large
vascular veins called coronary sinus, located at the
posterior surface of the heart.

91. Coronary will empties into right atrium.
The main tributaries carrying blood into the coronary
sinus are:
Great cardiac vein – drains the anterior aspect of the
heart.
Middle cardiac vein – drain the posterior aspect of the
heart.

93. Figure 19.11b

94. Lungs
Paired cone shaped organ in the thoracic cavity
Separated each other by the heart and other structures in
the mediastinum.
2 layers of serous membrane, called the pleural membrane
enclose and protect the lungs.
The superficial layer lines the wall of the thoracic cavity
called the parietal pleura.
The deep layers cover the lungs themselves call visceral
pleura.

96. Figure 10.16 The relationship of the pleura to the lungs.
Copyright © Elsevier Ltd 2005. All rights reserved.

97. Between the visceral and prietal pleurae is a small
space called pleural cavity.
Pleural cavity contains small amount of lubricating
fluid called pleural fluid.
Pleural fluid reduces friction between 2 membranes,
allowing them to slide easily over one another during
breathing.
pleural fluid also causes the 2 membranes to adhere
to one another. (surface tension)

98. The lungs extend from the diaphragm to just slightly
superior to the clavicles and lie against the ribs
anteriorly and posteriorly.
The broad inferior portion of the lung, the base, is
concave and fits over the convex area of the
diaphragm.
The narrow superior portion of the lung is the apex.

100. The surface of the lung lying against the ribs, the costal
surface, matches the rounded curvature of the ribs.
The mediastinal (medial) surface of each lung contain the
region, the hilus, through which bronchi, pulmonary
blood vessel, lymphatic vessels,
These structure are held together by the pleura and
connective tissue and constitute the roots of the lung.
Medially, the left lung also contains a concavity, the
cardiac notch, in which the heart lies.

102. Apex of the lungs lies superiorly to the medial third of
the clavicles
Anterior, lateral, and posterior surface of the lungs lie
against the ribs.
Base of the lung extends from the 6th costal cartilage
anteriorly to the spinous process of the T10
posteriorly.
The pleura extend about 5cm below the base from the
6th costal cartilage anteriorly to the 12th rib posteriorly.

104. Lobe and Fissure
The left lung has 2 lobes (superior, inferior) and the
right lung has 3 lobes (superior, inferior, middle).
The bulk of the lung surface is against the ribs and is
called the costal surface.
Other surfaces include the diaphragmatic and
mediastinal.
Each lung also has 3 borders: anterior, posterior and
inferior.
In both lungs, the superior and inferior lobes are
separated by the oblique fissure.
In the right lung, the superior lobe is further divided
into the superior and middle lobes, which are
separated by the horizontal fissure.

105. RIGHT LUNG LEFT LUNG
Oblique Fissure
Horizontal Fissure
Oblique Fissure

106. The anterior border of
the left lung is pushed
out by the heart and
this notch is called the
cardiac notch. If you
follow this notch
inferiorly, you will find
a small lingular lobe

107. Root of the right lung
bronchi lie posterior
pulmonary arteries are
superior
pulmonary veins are
inferior and anterior

108. Root of the left lung
bronchus lies posterior
pulmonary artery is
superior
pulmonary vein is
inferior and anterior

109. On the mediastinal surface
of the right lung, you will
find these structures
azygos vein and its arch
(over the root of the lung)
phrenic nerve anterior to the
root of the lung
vagus nerve posterior to the
root of the lung
esophagus

110. On the mediastinal surface
of the left lung, you will find
these structures:
descending aorta
arch of the aorta over the
root of the lung
right common carotid artery
right subclavian artery
phrenic nerve anterior to
the root of the lung
vagus nerve posterior to the
root of the lung

113. Blood Supply to Lungs
2 sets of artery
Pulmonary arteries
Bronchial arteries

114. Pulmonary Arteries
Deoxygenated blood passes through the pulmonary
trunks
Divide into left and right pulmonary arteries
Enter left and right lungs
Return oxygenated blood to the heart (left atrium)
through 4 pulmonary veins.

116. Bronchial artery
Branch from the aorta
Deliver oxygenated blood to the lungs tissues
This blood perfuse the walls of bronchi and bronchioles.
Deoxygenated blood return to the heart through
pulmonary artery
Some blood, however drains into bronchial veins,
branches of the azygos system returns to the heart via
superior vena kava.