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Cardiac Anatomy
Internal Anatomy of the Heart
Chambers of the •
heart
Right & left atrium –
Separated by the •
interatrial septum
Right & left ventricle –
Separated by the •
interventricular
septum
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Structure of the Heart Wall
Epicardium = “upon •
the heart” = visceral
pericardium
Dense fibrous –
connective tissue
Myocardium is the •
middle layer
Cardiac muscle –
Endocardium = “inside •
the heart”
Simple squamous –
epithelium
Human Anatomy, 3rd edition
Prentice Hall, © 2001
The Great Vessels
Superior & inferior •
vena cava
Return blood from –
body to right atrium
Coronary Sinus •
Returns blood from –
heart wall to right
atrium
Human Anatomy, 3rd edition
Prentice Hall, © 2001
The Great Vessels
Pulmonary veins •
Return blood –
(oxygenated) from
lungs to left atrium
Aorta •
Takes blood from –
left ventricle to
body
Pulmonary artery •
Takes blood –
(deoxygenated)
from right ventricle
to lungs
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Valves of the Heart
Atrioventricular (AV) 
valves separate the
atria from the ventricles
Tricuspid valve –
right
Bicuspid valve 
(mitral) – left

Semilunar valves 
separate the ventricles
from the great vessels
Pulmonary 
semilunar valve
Aortic semilunar
valve

Human Anatomy, 3rd edition
Prentice Hall, © 2001
Valves of the Heart (Ventricular Diastole)
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Valves of the Heart (Ventricular
Systole)
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Conducting System of the Heart
Depolarization spreads up the ventricular •
walls via Purkinje fibers.
Ventricles contract –
Human Anatomy, 3rd edition
Prentice Hall, © 2001
The Cardiac Cycle
Contraction pattern •
of the myocardium
Determined by the –
conduction system
Systole = contraction –
Diastole = relaxation –
Both atria contract •
Both ventricles •
contract
Atria alternate with •
ventricles
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Conduction System of the Heart
The average heart rate is 72 beats/min. •
Depolarization stimulates contraction •
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Conducting System of the Heart
Depolarization begins in the sinoatrial (SA) node •
Pacemaker –
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Conduction System of the Heart
•Depolarization spreads through atria, atria contract
Conducting System of the Heart
Atrioventricular (AV node) depolarizes •
Depolarization travels down the AV bundle (bundle •
of His)
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Conducting System of the Heart
Depolarization spreads up the ventricular •
walls via Purkinje fibers.
Ventricles contract –
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Pulmonary trunk
Arteries of thorax
Arises from right ventricle •
Runs up, back ,and to the left •
Bifurcates inferior to aortic arch into •
right and left pulmonary arteries, one
for each lung
Pulmonary arteries
Right pulmonary artery－passes •
posterior to ascending aorta and
superior vena cava to hilum of right
lung
Left pulmonary artery－passes •
anterior to descending aorta and left
main bronchus to hilum of left lung
Arterial ligament － remnant of ductus arteriosus, connects bifurcation of
pulmonary trunk to inferior border of aortic arch
Triangle of ductus arteriosus
Bounded by phrenic n., left vagus n. and left pulmonary a.
•
Contents－ arterial ligament , left recurrent n. and superficial cardiac
plexuses
•
Ascending aorta
Runs upward, forward and •
to the right,
Extends to level of second •
right sternocostal joint
Branches: right and left •
coronary arteries
Aortic arch
Continuation of ascending aorta
•
Curves upward, to the left and
•
posteriorly, then downward, arching
over left principal bronchus and
pulmonary trunk to lower border of T4
level, to become descending aorta
Branches (from right to left )
•
Brachiocephalic trunk－extends to right
sternoclavicular joint, bifurcates into
right subclavian and right common
carotid arteries
Left common carotid artery
–
Left subclavian artery
–
Aortic isthmus－baroreceptor
•
Aortic glomera－chemoreceptor
•
–
Thoracic
aorta
Continuation of aortic arch at lower border of T4
•
Courses downward on left side of, then in front of
vertebral column
Passes through aortic hiatus of diaphragm at level of
T12 vertebra to enter abdominal cavity
Main branches
•
Parietal branches
–
Nine pairs posterior intercostals arteries
•
One pair subcostal artery
•
For lower nine intercostals spaces and upper
•
part of abdominal wall; superior phrenic
arteries supply the superior surface of the
diaphragm.
Visceral branches
–
Bronchial branches: one or two for each lung
•
Esophageal branches
•
Pericardial branches
•
•
•
Internal thoracic artery －
descends into thorax 1.2cm
lateral to edge of sternum,
and ends at the sixth costal
cartilage by dividing
musculophrenic and
superior epigastric arteries
Veins of thorax
Brachiocephalic veins
Formed by union of internal jugular and
subclavian veins posterior to the
sternoclavicular joint
Angle of union is termed venous angle
Superior vena cava
•
•
Formed by union of right and left
•
brachiocephalic veins behind the right
sternocostal synchorndrosis of first rib
Runs vertically down on right of ascending
•
aorta
Joined by azygos vein at level of sternal angle
•
Enters right atrium at lever of lower border of
•
third right sternocostal joint
Collects blood from veins of upper half of body
•
Azygos vein
Begins as continuation of right ascending •
lumbar vein
Ascending along the right side of •
vertebral column
Joins superior vena cava by arching above •
right lung root at level of T4 to T5
Receives right posterior intercostals and •
subcostal veins plus some of bronchial,
esophageal and pericardial veins, and
hemiazygos vein
Tributaries－hemiazygosv. and accessory •
hemiazygos v., which receive most left
posterior intercostals vein and left
bronchial veins
Veins of vertebral column
Consists of
External vertebral •
venous plexus
Internal vertebral •
venous plexus
The lymphatic drainage of thorax
The lymphatic drainage of
thoracic wall
To axillary lymph nodes •
To parasternal lymph nodes •
(along internal thoracic vessels)
To intercostals lymph nodes •
from deeper structures
lymph nodes of the thoracic contents
lymph nodes of trachea, bronchi
and lungs
Pulmonary lymph nodeslie in the •
angles of bifurcation of branching
lobar bronchi
Bronchopulmonary hilar lymph •
nodes－lie in the hilus of the lung
Tracheobronchial lymph nodes－ •
situated above or below the
bifurcation of trachea
Paratracheal lymph nodes
－ •
along each side of the trachea
Anterior mediastinal •
lymph node lies anterior to
the large blood vessels of thoracic
cavity and pericardium; the
efferents unite with those of
paratracheal lymph nodes, to form
the right and left
bronchomediastinal trunks The
left bronchomediastinal trunk
terminates in thoracic duct, and
right in the right lymphtic duct
Posterior mediastinal •
lymph nodes lie along the
esophagus and thoracic aorta
Thoracic duct
Begins in front of L1 as a dilated sac, the •
cisterna chyli which formed by joining of left
and right lumbar trunks and intestinal trunk
Enter thoracic cavity by passing through the •
aortic hiatus of the diaphragm and ascends
along on the front of the vertebral column,
between thoracic aorta and azygos vein
Travels upward, veering to the left at the level •
of T5
At the roof of the neck, it turns laterally and •
arches forwards and descends to enter the
left venous angle
Just before termination, it receives the •
left jugular, subclavian and
bronchomediastinal trunks
Drains lymph from lower limbs, pelvic •
cavity, abdominal cavity, left side of thorax,
and left side of the head, neck and left
upper limb
Right lymphatic duct
Formed by union of right jugular, •
subclavian, and bronchomediastinal
trunks
Ends by entering the right venous angle •
Receives lymph from right half of head, •
neck, thorax and right upper limb
Phrenic nerve
Descends over scalenus anterior •
to enter thorax
Accompanied by •
pericardiophrenic vessels and
passes anterior to lung roots
between mediastinal pleura and
pericardium to supply motor and
sensory innervation to
diaphragm
Sensory fibers supply to pleurae, •
pericardium and peritoneum of
diaphragm; usually right phrenic
nerve may be distributed on live,
gallbladder and biliary system.
Left vagus nerve
Enter thoracic inlet between left •
common carotid and left subclavian
arteries, posterior to left
brachiocephalic vein
Crosses aortic arch where left recurrent •
laryngeal nerve branches off
Passes posterior to left lung root •
Forms anterior esophageal plexus •
Forms anterior vagal trunk at •
esophageal hiatus where it leaves
thorax and passes into abdominal cavity ,
then divides into anterior gastric and
hepatic branches
Right vagus nerve
Enter thoracic inlet on right side of •
trachea
Travels downward posterior to •
right brachiocephalic vein and
superior vena cava
Passes posterior to right lung root •
Forms posterior esophageal plexus •
Forms posterior vagal trunk at •
esophageal hiatus where it leaves
thorax and passes into abdominal
cavity, then divides into posterior
gastric and celiac branches
Recurrent laryngeal nerves
Right one hooks around right •
subclavian artery, left one hooks aortic
arch
Both ascend in tracheo-esophageal •
groove
Nerves enter larynx posterior to •
cricothyroid joint, the nerve is now
called inferior laryngeal nerve
Innervations: laryngeal mucosa below •
fissure of glottis , all laryngeal
laryngeal muscles except cricothyroid
Bronchial and esophageal
branches
Thoracic sympathetic trunk
Branches of sympathetic trunk to thoracic •
plexuses
Greater splanchnic nerve formed by •
preganglionic fibers from T5~T9 ganglia, and
relay in celiac ganglion.
Lesser splanchnic nerve formed by •
preganglionic fibers from T10~T12 ganglia,
and relay in aorticorenal ganglion.
The postganglionic fibers supply the liver, •
spleen, kidney and alimentary tract as far as
the left colic flexure.
Aortic arch
Continuation of ascending aorta •
Curves upward, to the left and
•
posteriorly, then downward,
arching over left principal
bronchus and pulmonary trunk
to lower border of T4 level, to
become descending aorta
Branches (from right to left ) •
Brachiocephalic trunk－ –
extends to right
sternoclavicular joint,
bifurcates into right
subclavian and right common
carotid arteries
Left common carotid artery –
Left subclavian artery –
Contents
The superior mediastinum contains so
many important structures that it is best to
.consider it in stages:
Stage 1: the esophagus
The most posterior structure, closely related to
the vertebrae (T1-T4), is the esophagus with the
thoracic duct running up its left side. It is
flattened anteroposteriorly. As it descends, it
inclines slightly towards the left but is pushed
back to the median plane by the arch of the
aorta
Stage 2: the trachea
In front of the upper part of the esophagus
is the trachea, which inclines slightly to the
right and bifurcates at the level of the
manubriosternal joint. Because of tracheal
inclination, the right bronchus is more in
line with the trachea than the left. The
posterior surface of the trachea is flat
where it is applied to the esophagus. It is
kept patent by a series of C-shaped bars of
cartilage.
Between the trachea and esophagus on the
left side is the left recurrent laryngeal
nerve, which comes from the vagus nerve
and hooks under the ligamentum
arteriosum. The arch of the aorta arches
over the root of the left lung; the azygos
vein arches over the root of the right lung.
In front of the tracheal bifurcation is the
pulmonary trunk dividing into left and right
pulmonary arteries. This has the
appearance of a (T) with a sloping
The right pulmonary artery passes to the right lung
behind the ascending aorta, superior vena cava and in
front of the esophagus and right main bronchus. The
left pulmonary artery goes to the left lung in front of
the descending aorta and left main bronchus. The
beginning of the left pulmonary artery is connected to
the under surface of the aorta by the ligamentum
arteriosum, a remnant of the fetal ductus arteriosus
that short-circuited the functionless lungs by
diverging most of the right ventricular outflow into
the aorta. Also in front of the tracheal bifurcation are
the tracheobronchial lymph nodes and the cardiac
plexus.
The barchiocephalic trunk passes superolaterally to
the right side of the trachea and the right
sternoclavicular joint, where it divides into the right
common carotid and right subclavian arteries. The
arch of the aorta passes to the left of the trachea and
esophagus, displacing the trachea to the right and
constricting the esophagus.
The left phrenic nerve crosses the arch of the aorta in
front of the vagus. The left superior intercostal vein
crosses the arch from back to front, over the vagus
and under the phrenic, relationships similar to those
of the azygos vein on the right side, which is
embryologically equivalent to it.
Since the arch is entirely behind the manubrium sterni, the
left brachiocephalic vein is only just below the jugular
(suprasternal) notch and is actually above it in children. The
brachiocephalic veins, which arise posterior to
sternoclavicular joints, unite to form the superior vena cava at
the level of the inferior border of the first right costal
cartilage.
The superior vena cava lies just to the right of the ascending
aorta before opening into the right atrium at the level of the
right 3rd costal cartilage. The only other tributary of the
superior vena cava is the azygos vein. The brachiocephalic
veins receive a number of tributaries including the left
superior intercostal vein (into left brachiocephalic)
the inferior thyroid veins which come down from the neck in
front of the trachea, the vertebral veins, and the internal
thoracic veins.
Stage 3: the great arteries
The arch of the aorta passes backwards as well
as to the left. The junction between the ascending
aorta and the arch is at the level of the lower
border of T4. Thus the whole arch is in the
superior mediastinum. The major branches of the
arch spiral around the trachea and esophagus (at
first anterior then on either side); these are the
brachiocephalic trunk (innominate), the left
common carotid and the left subclavian arteries
respectively.
The bronchial arteries to the lungs and the
thyroidea ima artery to the thyroid gland may
arise from the aortic arch.
Stage 4: the great veins
In the embryo the venous system is, at first,
symmetrical but cross-connections drain most of the
blood across the midline to the right. In the thorax the
cross-channel is the left brachiocephalic vein. Hence
both superior and inferior venae cavae are on the
right and open into the right atrium.
Each brachiocephalic vein is formed by the junction of
the corresponding subclavian and internal jugular
veins; the left brachiocephalic crosses the midline just
above the arch of the aorta.
Stage 5: The thymus gland
This important component of the lymphatic system lies
behind the manubrium sterni but may extend up into the
neck or down in the anterior mediastinum. It is molded
around the great vessels and trachea but you may not be able
to recognize it in the dissecting room since in adult life it is
gradually replaced by fat. Because of the deposition of fat
after puberty the pink color of the infant’s thymus changes to
yellow. It reaches its largest size just before puberty but,
relative to the adjacent structures, it appears at its largest
about the time of birth. The rich arterial supply is derived
mainly from the anterior intercostal and branches of the
internal thoracic arteries. The veins end in the left
brachiocephalic, internal thoracic, and inferior thyroid veins.
Notes on the general topography of the superior
mediastinum:
1. The superior mediastinum is in direct continuity
with the anterior and posterior mediastinum and
their separation from it is purely descriptive, not
anatomical.
2. The plane of the sternal angle passes through the
bifurcation of the trachea, the concavity of the arch of
the aorta, and just above the bifurcation of the
pulmonary trunk. On the plane the azygos vein enters
the superior vena cava, the thoracic duct reaches the
left side of the esophagus in its passage upwards from
the abdomen. Also lying in the plane are the
ligamentum arteriosum, and both superficial and
3. The great veins and arteries of the superior
mediastinum are asymmetrical. The veins are on the
right, arteries on the left.
a midline Structures like trachea or bilateral like the
apices of lungs or the phrenic and vagus nerves, thus
have asymmetrical relationships on the right and left
side.
4. Veins expand enormously, large arteries not at all,
during increased blood flow. Thus there is much
"dead space" on the right, none on the left, and it is
into this space on the right side that tumors of the
mediastinum or liquid collections tend to project.
5. The structures in the mediastinum form the
medial relations of the lungs, being separated
from them by the mediastinal pleura. Some of
them make deep groove on the lungs. The left
lung is intended by the left ventricle of the
heart, the arch of the aorta, the subclavian
artery and the left brachiocephalic vein, and
perhaps lower part of the esophagus. Right lung
carries impressions for the right atrium,
subclavian artery and brachiocephalic vein, the
superior vena cava, the azygos vein and the
esophagus.
Inferior mediastinum
Anterior mediastinum
Location－posterior to
body of sternum and
attached costal cartilages,
anterior to heart and
pericardium
Contents－fat, remnants
of thymus gland, anterior
mediastinal lymph nodes
•
•
The posterior mediastinum
This contains esophagus, the
descending aorta, the azygos venous
system and the thoracic duct. It may be
regarded as a duct leading from the
neck and superior mediastinum to the
abdomen so that all the structures
mentioned above (in addition to the
inferior vena cava) have to pass
through the diaphragm.
Posterior mediastinum
Location－posterior to •
heart and pericardium,
anterior to vertebrae T5－
T12
Contents: esophagus, •
vagus n., thoracic aorta,
azygos system of veins,
thoracic duct, thoracic
sympathetic trunk,
posterior mediastinal
lymph nodes
Posteriorly－posterior •
esophageal plexus,
thoracic aorta, thoracic
duct, azygos v.,
hemiazygos .,accessory
hemiazygos v., right
posterior intercostal v.
Relations of thoracic aorta
Anteriorly－left root of lung, •
pericardium and esophagus
Posterior－ hemiazygos v., •
accessory hemiazygos v.,
Right－azygos v. and thoracic •
duct
Left－mediastinal pleura •
Mediastinal spaces
Retrosternal space lies •
beween sternum and
endothoracic fascia
Pretracheal space －lies •
within superior mediastinum,
between trachea, bifurcation
of trachea and aortic arch
Retroesophagus space － •
lies within superior
mediastinum, beween
esophagus and endothoracic
fascia
Relations of esophagus
Anteriorly－trachea, •
bifurcation of trachea, left
principal branchus, left
recurrent n., right
pulmonary a., anterior
esophageal plexus,
pericardium, left atrium,
diaphragm
Left side of mediastnum
Left subclavian a.
Thoracic duct
Left vagus n.
Left recurrent n.
Phrenic n. &
pericardiacophrenic a.
Aortic arch
Thoracic aorta
Sympathetic trunk
Root of lung
Pericardium
Esophagus
Greater splanchnic n
Right side of mediastnum
Trachea
Left vagus n.
Arch of azygos v.
Azygos v.
Sympathetic trunk
Esophagus
Inferior vena cava
Superior vena cava
Phrenic n. &
pericardiacophrenic a.
Root of lung
Pericardium
Posterior layer •
Trachea –
Esophagus –
Thoracic duct –
Relations of aortic arch
Anteriorly and to the left － •
pleura, lung，phrenic n.,
pericardiacophrenic vessels and
vagus n.
Posteriorly and to the right－ •
trachea, esophagus, left recurrent n.,
thoracic duct, deep cardiac plexus
Superiorly－its three branches, left •
brachiocephalic v. and thymus
Inferiorly－pulmonary a., arterial •
ligament, left recurrent n., left
principal bronchus and superficial
cardiac plexus
Left－left common carotid a., left subclavian a., aortic arch,
thoracic aorta, superior part of thoracic duct
Right－arch of azygos v. •
•