Easy way to learn Blood supply of the heart and Blood supply of the hear. simple way to learn by trick and easy form. cardiovescular system

1. BLOOD AND
NERVE SUPPlY
OF THE HEART
BY
(MOHAMMAD SHOEB)

2. BLOOD SUPpLY OF THe HEART
The heart is a muscular, four-chambered organ the
responsible for distributing blood throughout the body.
The continuous body of the heart creates a large
demand for nutrients a large demand for nutrients to
be delivered to cardiac tissue and for waste to be
removed.
However, because the organ is several layers thick, it is
not feasible for the tissue to obtain nutrients from the
blood (via any from cellular transport mechanism) that
passes through its chamber.

3. If that were the case, the inner layers of the heart
(endocardium and deep myocardium) would receive
nutrients, but the outer layers (superficial myocardium,
pericardium, and epicardium) would become ischaemic
and necrotic .
Therefore, in order to maintain optimum cardiac
performance and homeostasis, the heart has a network
of blood vessels known as the coronary vessels that
take nutrient-rich blood to the heart tissue; as well as
coronary veins that removes waste products from the
cardiac myocytes.
Their role is similar to that of the vasa nervosa (vessels
of the nerves) and vasa vasorum (vessels of the vessels)
that perfuse the outer layers of the larger blood vessels.
Key facts about the blood supply of the heart
Arterial
supply
Left coronary artery (left anterior descending, left
circumflex arteries), right coronary artery (conus arteriosus,
right anterior atrial and ventricular, right marginal,
posterior interventricular arteries)
Venous
drainage
Anterior cardiac veins, Thebesian veins, coronary sinus
(great cardiac vein, middle cardiac vein, small cardiac vein,
oblique vein of the left atrium, posterior vein of the left
ventricle
Lymphatic
drainage
Tracheobronchial and brachiocephalic lymph nodes

4. 1. Overview
The word coronary arises from the Latin word c o r o n a
r i u s , which in English means “belonging to a crown or
wreath” . When viewed in cross-section from above, the
coronary vessels resemble a tilted, inverted crown
wrapped around the root of the great vessels.
 The coronary arteries are responsible for carrying
nutrient-rich, oxygenated blood from the left ventricle
to the myocardium; while the coronary veins take
nutrient – poor deoxygenated blood away from the
myocardium and to the right atrium.
Although the coronary arteries and their branches are
considered as end arteries, they participate in various
anastomoses (especially during intrauterine life).
2. Coronary arteries
The coronary arteries arise from the root of the ascending aorta.
Recall that the aortic valve has three semilunar cusps, also known
as the sinuses of Valsalva. The left and right semilunar cusps give
rise to the corresponding left and right coronary arteries
(respectively). The third sinus – which is the posterior semilunar
cusp – is not associated with a coronary vessel and is also called the
non-coronary sinus. The major divisions of the coronary arteries
usually travel just below the epicardial layer of the heart. However,
their branches may become deeply embedded in the myocardium

5. as they pass through the cardiac grooves. The proximal end of the
coronary arteries range between 1.5 – 5.5 mm in diameter; but the
left coronary is typically larger than the right in most cases.
 Anatomists and clinicians alike refer to ‘right’ or ‘left’ dominance
with respect to the blood supply of the heart. If the right coronary
artery gives off the posterior interventricular branch (which
perfuses the posterior region of the ventricular septum and the
posterolateral aspect of the left ventricle),
 then the heart would be described as being right dominant; the
converse is also true. In the majority of cases, the right coronary is
Coronary circulation variation in a cadaver: This cadaveric specimen exhibits a rare variant of
coronary arteries. The LCA (LMCA) does not stem from the ostium of the left aortic sinus, like
it normally does. As you can see in this example, the LCA subsequently branches off into the
LAD and LCx arteries. (LCA: Left coronary arter, LMCA: Left main coronary artery, LAD: Left
anterior descending artery, LCx: Circumflex artery)

6. the dominant artery; however, both left dominance, and
codominance (equal supply from both coronary arteries) have been
observed.
 a simplified segmentation system where the coronary vessels are
divided into proximal, mid, and distal thirds will be used.
 The left coronary artery arises from the left semilunar cusp (sinus of
Valsalva). The initial portion of the vessel ends at the first
bifurcation; it is of variable length and is often referred to as the left
main coronary artery. It can be found travelling between the left
atrial (auricular) appendage and the pulmonary trunk.
 When compared to the right coronary artery, the left coronary
artery tends to be larger and is responsible for supplying a larger
territory. It supplies the left atrium, majority of the left ventricle,
and most of the interventricular septum.
2.1 Branches of the left coronary artery
 As soon as the right coronary artery enters the atrioventricular
septum, the left coronary artery then splits to give rise to the
anterior interventricular artery (also known as the left anterior
descending artery) and the left circumflex artery.
 The anterior interventricular artery is viewed as a caudal, anterior
continuation of the left coronary artery. It travels inferolaterally within the
anterior interventricular groove towards
the cardiac apex. It is more often than not,
covered by bridging myocardial fibers, as
well as sections of the great cardiac vein.
The first branch of this artery is the left
conus artery close to the point of origin. It
often decussates to anastomose with the
contralateral counterpart, as well as the
vasa vasora of the aorta and pulmonary
artery.

7.  The artery produces anterior ventricular and anterior septal divisions as
well; each having left and right components. It also gives rise to posterior
branches that correspond to the previously described anterior derivatives.
 The other branch of the left coronary artery is the left circumflex
artery. It is overlapped by the left atrial appendage proximally, as it
takes a left course in the atrioventricular groove and crosses over
the obtuse border. The vessel may give rise to atrial branches
(posterior, lateral and anterior divisions) that supply the left atrium.
2.2 Right coronary artery
 The right coronary artery arises from the right semilunar cusp (sinus
of Valsalva). In the majority of cases, the artery arises as a single
vessel. However, as many as four branches have been observed
arising from the anterior coronary ostium. The artery travels
between the right appendage of the right atrium and the
pulmonary trunk, in an anterior direction to gain access to the right
half of the atrioventricular groove.

8. Branches of the right coronary artery
 The right anterior ventricular and
atrial branches originate from the
proximal segment of the right
coronary artery; which extends from
the right coronary ostia and ends at
the right cardiac margin.
 The right marginal and anterior
divisions often occur as paired
vessels that supply the entire right
atrium. On the other hand, the right posterior atrial branch usually
exists as a solitary branch that supplies both right and left atria.
 The anterior atrial division of the right coronary artery also
produces the sinoatrial node artery.
 The ramus cristae terminalis also arises from these vessels and
directly supplies the sinoatrial node.
 As the right coronary artery continues toward the right cardiac
margin in the sternocostal atrioventricular groove, it produces the
right marginal artery.
3. Coronary veins
 Like all arteries in the body, there are veins that accompany them
to drain the tissue of deoxygenated blood. Similarly, the veins of
the heart often travel alongside the arterial vessels, carrying blood
back to the heart.
 There are numerous venous tributaries traversing the surface of
the heart. They eventually coalesce to form the coronary sinus,
which drains indirectly into the right atrium. Additionally, the

9. anterior cardiac veins and the Thebesian (small) veins drain directly
into the cardiac chambers.
3.1 Anterior cardiac veins
 Up to five vessels traversing the subepicardial space towards the
right aspect of the septal atrioventricular groove form the group of
anterior cardiac veins.
 The anterior cardiac veins may also receive blood from the right
marginal vein as it travels along the acute cardiac border.
However, this vein has also been found to drain independently
into the right atrium as well as to the coronary sinus. The anterior
cardiac veins are responsible for draining the sternocostal aspect
of the right ventricle.
3.2 Thebesian veins
 The smallest cardiac veins (venae cordis minimae) are a
collection of small veins of the heart. Otherwise known as
Thebesian veins or small cardiac veins, these vessels range from
0.5 – 2 mm in diameter. Although they are difficult to map
throughout the heart, they have been shown to drain directly into

10. all cardiac chambers. However, it is far more likely to find the veins
draining into the right, rather than in the left, chambers.
3.3 Coronary sinus
 The coronary sinus is roughly a
3 cm saccular dilatation between
the left cardiac chambers. The
sinus commences at the junction
of the great cardiac vein and the
oblique vein of the left atrium. It
is oriented obliquely in the
posterior atrioventricular groove;
partly overlying the cardiac crux.
Its opening into the right atrium (between the inferior vena caval
orifice and opening of the tricuspid valve) is protected by the
semilunar valve of the coronary sinus (also called the Thebesian
valve), in order to prevent reflux into the cardiac venous system.
At least five other cardiac veins drain invariably into the coronary
sinus.
3.4 Great cardiac vein
 The great cardiac vein originates at the cardiac apex, travels
through the anterior interventricular and then to the
atrioventricular groove. It receives blood from the left marginal
vein and other tributaries that drain both ventricles and the left
atrium, and empties into the coronary sinus at its origin.
3.5 Middle cardiac vein
 Also arising at the cardiac apex, the middle cardiac vein travels in
the posterior interventricular groove to empty into the atrial end
of the coronary sinus.

11. 3.6 Small cardiac vein
 Not to be confused with the Thebesian veins,
the small cardiac vein is a singular vessel found
in the posterior atrioventricular groove. It is
sometimes joined by the right marginal vein
(which travels along the acute cardiac border)
as they drain the posterior aspect of the right
chambers.
3.7 Oblique vein of the left atrium
 As the name suggests, the oblique vein of left atrium takes an inferior
oblique course along the back of the left atrium to insert in the distal end
of the coronary sinus. Like the left vena caval ligament (with which it is
continuous), the oblique vein of the left atrium is a remnant of the left
common cardiac vein.
3.8Posterior vein of the left ventricle
 The posterior vein of left ventricle opens centrally in the coronary sinus.
However, it may also open into the great cardiac vein. It travels along the
diaphragmatic aspect of the left ventricle, alongside the middle cardiac
vein.
4. Lymphatic drainage of
the heart
 The lymphatic channels of the heart commence in the subendocardial
and myocardial spaces. These tributaries then drain into the subepicardial
plexus. From here, the efferent subepicardial vessels coalesce to form right
and left cardiac collecting trunks.
 Tributaries from the right atrium, diaphragmatic aspect of the right
ventricle, and the right cardiac border drain into the right truncal lymph
vessels. These vessels also travel cranially in the atrioventricular groove,

12. adjacent to the right coronary artery. Subsequently, it climbs the outer
wall of the ascending aorta to access the brachiocephalic nodes.
5. Summary of coronary
vessels
The heart is a muscular organ that works continuously from the 4th week
of intrauterine life until death.
In the anatomical position, the heart has six surfaces and four borders
that are named in relation to adjacent anatomical structures and their
geometrical orientation, respectively:
The surfaces of the heart are:
o The anatomical base is the posterior surface of the heart
and is made up mostly by the left, and part of the right,
atria.
o The sternocostal surface is the anterior surface of the heart that sits
immediately behind the sternum; and is made up mostly by the right
atrium and ventricle, and a portion of the auricle of the left atrium.
The diaphragmatic surface is the inferior surface of the heart and is
made up mostly by the left ventricle.
o The anatomical apex of the heart is the pinnacle of the
pyramid; normally found in the left fifth intercostal
space, in the midclavicular line of the recumbent
patient.
o The right cardiac surface is almost vertical and consists
of the wall of the right atrium.
o The left cardiac surface is oblique and faces
posterosuperiorly to the left hand side.
The cardiac margins include:
o The obtuse (left) margin
o The acute (inferior) margin

13. o The right heart margin
o The superior heart margin
There are impressions on the surface of the heart that serve as
landmarks for the septa that separate the chambers internally.
They also provide a course for the coronary vessels to travel in:
o The anterior and posterior interventricular groove
corresponds to the interventricular septum
o The coronary sulcus corresponds to the atrioventricular
septum
o The interatrial groove matches up to the interatrial
septum
The blood supply to the heart arises from the left and right
semilunar cusps of the aortic valve (respectively):
o The left coronary artery gives rise to the anterior
interventricular (left anterior descending) and the left
circumflex arteries.
o The left circumflex becomes the posterior
interventricular artery in a few cases
The venous drainage of the heart includes:
o The anterior cardiac veins
o Thebesian Veins
The coronary sinus and its tributaries:
o The great cardiac vein
o The middle cardiac vein
o The small cardiac vein
o The oblique vein of the left atrium
o The posterior vein of the left ventricle
The lymphatic channels of the heart drain to the
tracheobronchial and brachiocephalic lymph nodes.

14. Nerve supply of the heart
“The innervation of the heart refers to the network of
nerves that are responsible for the functioning of the
heart. The heart is innervated by sympathetic and
parasympathetic fibres from the autonomic branch of
the peripheral nervous system.”
The network of nerves supplying the heart is called the
cardiac plexus. It receives contributions from the right and
left vagus nerves, as well as contributions from the
sympathetic trunk. These are responsible for influencing

15. heart rate, cardiac output, and contraction forces of the
heart.
Key facts about the innervation of the heart
Parasympathetic
efferent fibers
Vagus nerve F u n c t i o n : reducing the heart rate,
reducing the force of contraction of the heart,
vasoconstriction of the coronary arteries
Sympathetic efferent
fibers
Cardiac nerves from the lower cervical and upper thoracic
ganglia F u n c t i o n : increasing heart rate, increasing the
force of contraction of the myocardium
Afferent
parasympathetic
fibers
Vagal cardiac nerves F u n c t i o n : feedback on blood
pressure
Afferent sympathetic
fibers
Afferents to upper thoracic and lower cervical ganglia F u n
c t i o n : feedback on blood pressure, pain sensation
Clinical relations Cardiac plexus injury, referred pain
This article will discuss the innervation of the heart.
1. The cardiac plexus
The cardiac plexus is a network of nerves including both
the sympathetic and parasympathetic systems. It is
split into two parts. The superficial part is located
below the arch of the aorta, and between the arch and
the pulmonary trunk.
The deep part lies between the arch of the aorta and
the bifurcation of the trachea. Small mixed fibres

16. (containing both sympathetic and parasympathetic
fibres) branch off of the cardiac plexus and supply:
 the conduction system of the heart
 the coronary vasculature
 the myocardium (muscle) of the atria and ventricles
1.1 Parasympathetic innervation
The parasympathetic portions of the cardiac plexus
receive contributions
from the vagus nerve
only. The preganglionic
fibres, branching from
the right and left vagus
nerves, reach the heart.
They enter the cardiac
plexus by synapsing with
ganglia within this plexus
and walls of the atria.
Parasympathetic innervation is responsible for:
 reducing the heart rate
 reducing the force of contraction of the heart
 vasoconstriction (narrowing) of the coronary
arteries

17. 1.2 Sympathetic innervation
The sympathetic part of the cardiac plexus is
composed of fibres from the sympathetic trunk,
arising from the upper segments of the thoracic
spinal cord. Fibres from the sympathetic trunk
reach the cardiac plexus via cardiac nerves. The
preganglionic fibres branch from the upper thoracic
spinal cord and synapse in the lower cervical and
upper thoracic ganglia. Postganglionic fibres
extend from the ganglia to the cardiac plexus.

18. Sympathetic nerves are responsible for:
 increasing heart rate
 increasing the force of contraction of the
myocardium
 the ‘fight or flight’ response, causing our
heart to beat faster.
1.3 Cardiac afferents
Afferent fibres also form part of the cardiac
plexus. They return to the central nervous system
via both the sympathetic cardiac branches and the
cardiac nerves from the right and left vagus nerves.
The afferents passing through the vagal cardiac
nerves return to the corresponding vagus nerve.
These afferents provide feedback on blood pressure
and blood chemistry.
In the sympathetic branch, the visceral afferents
return to the upper thoracic and lower cervical
ganglia. The fibres entering the upper cervical
region are typically redirected down towards the
upper thoracic portions of the sympathetic trunk,
where they reenter the upper thoracic regions of
the thoracic spinal cord, joining afferents from the
thoracic ganglia. Sympathetic afferents relay pain
sensation from the heart.

19. The following resources will help you to master the
innervation of the heart and cement your
knowledge.
2. Clinical notes
2.1 Cardiac plexus injury
Injury to the cardiac plexus, or in fact, to any of the
contributaries to the cardiac plexus can impair the function
of the heart. Damage to the vagus nerves, providing the
parasympathetic innervation of the heart, will affect the
ability to decrease the heart rate, leading to tachycardia.
Similarly, damage to the sympathetic fibres contributing to
the cardiac plexus can reduce the ability to increase heart
rate, causing bradycardia.
2.2 Referred pain
The pain conducting sympathetic afferents transmit pain
sensation. This pain sensation can be detected at a cellular
level in incidences where tissue damage to the heart occurs.
These incidences include cardiac ischemia and myocardial
infarction. The pain can often be felt in cutaneous regions.
This is because some of the dermatomes responsible for
cutaneous innervation are supplied by the same spinal cord
levels as the visceral afferents from the heart. This is the
mechanism behind pain being felt in the right shoulder
region that is a characteristic symptom of a myocardial
infarction.