Medical Student

1. Pericardium
Chitamu, Sedingo

2. • The pericardium is a double-walled fibroserous
membrane that encloses the heart and the roots of
its great vessels The internal surface of the fibrous
pericardium is lined with a glistening serous
membrane, the parietal layer of serous pericardium.
This layer is reflected onto the heart and great vessels
as the visceral layer of serous pericardium.

3. The pericardial sac is influenced by movements of the
heart and great vessels, sternum, and diaphragm
because the fibrous pericardium is:
• Fused with the tunica adventitia of the great vessels
entering and leaving the heart.
• Attached to the posterior surface of the sternum by
sternopericardial ligaments.
• Fused with the central tendon of the diaphragm

4. • The fibrous pericardium protects the heart against
sudden overfilling because it is unyielding and closely
related to the great vessels that pierce it superiorly
and posteriorly . The ascending aorta carries the
pericardium superiorly beyond the heart to the level
of the sternal angle

5. • The pericardial cavity is the potential space between
the opposing layers of the parietal and visceral layers
of serous pericardium . It normally contains a thin
film of serous fluid that enables the heart to move
and beat in a frictionless environment

6. • The visceral layer of serous pericardium forms the
epicardium, the external layer of the heart wall, and
reflects from the heart and great vessels to become
continuous with the parietal layer of serous
pericardium, where

7. • The aorta and pulmonary trunk leave the heart; a
finger can be inserted into the transverse pericardial
sinus located posterior to these large vessels .

8. • The SVC, inferior vena cava (IVC), and pulmonary
veins enter the heart; these vessels are partly covered
by serous pericardium, which forms the oblique
pericardial sinus , a wide recess posterior to the heart.
The oblique sinus can be entered inferiorly and will
admit several fingers; however, the fingers cannot
pass around any of these vessels because the sinus is
a blind recess (cul-de-sac

9. • The arterial supply of the pericardium is mainly from
the pericardiocophrenic artery , a branch of the
internal thoracic artery, which may accompany or
parallel the phrenic nerve to the diaphragm. Smaller
contributions of blood to the pericardium come
from the musculophrenic artery, a terminal branch of
the internal thoracic artery; the bronchial,
esophageal, and superior phrenic arteries from the
thoracic aorta; and the coronary arteries supplying
only the visceral layer of serous pericardium

10. • The venous drainage of the pericardium is from the
• Pericardiacophrenic veins, tributaries of the
brachiocephalic (or internal thoracic) veins.
• Variable tributaries of azygos venous system.
• The nerve supply of the pericardium is from the
• Phrenic nerves (C3-C5)a primary source of sensory fibers;
pain sensations conveyed by these nerves are commonly
referred to the skin (C3-C5 dermatomes) of the top of
the shoulder of the same side.

12. • The wall of each chamber of the heart consists of three
layers from superficial to deep
• Epicardium, a thin external layer (mesothelium) formed
by the visceral layer of serous pericardium.
• Myocardium, a thick middle layer composed of cardiac
muscle.
• Endocardium, a thin internal layer (endothelium and
subendothelial connective tissue) or lining membrane of
the heart that also covers its valves.

14. • The heart is shaped like three-sided pyramid with an
apex, base, and four surfaces.
• The apex of the heart
• Is directed anteriorly and to the left and is formed by
the inferolateral part of the left ventricle.
• Is located posterior to the left 5th intercostal space in
adults, usually 9 cm from the median plane.

15. • Is where the sounds of mitral valve closure are maximal
(apex beat); the apex underlies the site where the heartbeat
may be auscultated on the thoracic wall.
• The base of the heart
Is the heart's posterior aspect.
• Is formed mainly by the left atrium, with a lesser
contribution by the right atrium.
• Faces posteriorly toward the bodies of vertebrae T6-T9,
and is separated from them by the pericardium, oblique
pericardial sinus, esophagus, and aorta.

16. • Extends superiorly to the bifurcation of the
pulmonary trunk and inferiorly to the coronary
groove.
• Receives the pulmonary veins on the right and left
sides of its left atrial portion and the superior and
inferior venae cavae at the superior and inferior ends
of its right atrial portion

20. • The coronary arteries supply the myocardium and
epicardium and course just deep to the epicardium,
normally embedded in fat. The right and left
coronary arteries arise from the corresponding aortic
sinuses at the proximal part of the ascending aorta
just superior to the aortic valve. The endocardium
receives oxygen and nutrients directly from the
chambers of the heart.

21. • The right coronary artery (RCA) arises from the right
aortic sinus of the ascending aorta and runs in the
coronary groove (sulcus). Near its origin, the RCA usually
gives off an ascending sinuatrial (SA) nodal branch that
supplies the SA node, (part of the cardiac conducting
system). The RCA then descends in the coronary groove
and gives off the right marginal branch, which supplies
the right border of the heart as it runs toward (but does
not reach) the apex of the heart. After giving off this
branch, the RCA turns to the left and continues in the
coronary groove on the posterior aspect of the heart.

22. • At the crux (cross) of the heart, the junction of the septa
and walls of the four heart chambers, the RCA gives rise
to the AV nodal branch, which supplies the AV node (part
of the cardiac conducting system). The RCA then gives
off the large posterior IV branch that descends in the
posterior IV groove toward the apex of the heart . The
posterior IV branch supplies both ventricles and sends
perforating interventricular septal branches to the IV
septum. The terminal (left ventricular) branch of the RCA
then continues for a short distance in the coronary
groove. Typically, the RCA supplies

23. • The right atrium.
• Most of right ventricle.
• Part of left ventricle (diaphragmatic surface).
• Part of IV septum (usually posterior third).
• The SA node (in approximately 60% of people).
• The AV node (in approximately 80% of people

24. • The left coronary artery (LCA) arises from the left aortic
sinus of the ascending aorta and passes between the left
auricle and the left side of the pulmonary trunk in the
coronary groove. In approximately 40% of people, the SA
nodal branch arises from the circumflex branch of the
LCA and ascends on the posterior surface of the left
atrium to the SA

25. • node. At the left end of the coronary groove, located just
left of the pulmonary trunk, the LCA divides into two
branches, an anterior IV branch (left anterior descending
[LAD] branch) and a circumflex branch. The anterior IV
branch passes along the IV groove to the apex of the
heart. Here it turns around the inferior border of the
heart and anastomoses with the posterior IV branch of
the right coronary artery. The anterior IV branch supplies
both ventricles and the IV septum

28. • In many people, the anterior IV artery gives rise to a
lateral (diagonal) branch, which descends on the anterior
surface of the heart. The smaller circumflex branch of the
LCA follows the coronary groove around the left border
of the heart to the posterior surface of the heart. The left
marginal artery, a branch of the circumflex branch,
follows the left margin of the heart and supplies the left
ventricle. The circumflex branch of the LCA terminates
in the coronary groove on the posterior aspect of the
heart before reaching the crux, but in about one third of
hearts it continues as the posterior IV branch Typically,
the LCA supplies

29. • The left atrium.
• Most of left ventricle.
• Part of right ventricle.
• Most of IV septum (usually its anterior two thirds),
including the AV bundle of conducting tissue,
through its perforating IV septal branches.
• The SA node (in approximately 40% of people).

30. • Venous Drainage of Heart
• The heart is drained mainly by veins that empty into
the coronary sinus and partly by small veins that
empty directly into the chambers of the heart. The
coronary sinus, the main vein of the heart, is a wide
venous channel that runs from left to right in the
posterior part of the coronary groove. The coronary
sinus receives the great cardiac vein at its left end and
the middle and small cardiac veins at its right end.

32. • The left posterior ventricular vein and left marginal
vein also open into the coronary sinus. The small
anterior cardiac veins empty directly into the right
atrium and the smallest cardiac veins are minute
vessels that begin in the capillary beds of the
myocardium and open directly into the chambers of
the heart, chiefly the atria. Although called veins, they
are valveless communications with the capillary beds
of the myocardium and may carry blood from the
heart chambers to the myocardium.