heart description for medical students from clinical anatomy by richard s. snell

2. Heart

3. Pericardium
• Fibroserous sac that encloses the heart and
the roots of the great vessels
• Restrict excessive movements, lubrication
• Lies within the middle mediastinum
• Posterior to the body of the sternum and the
2nd to the 6th costal cartilages and anterior to
the 5th to the 8th thoracic vertebrae

4. • Fibrous Pericardium:
– strong fibrous part of the sac
– fimly attached below to the central tendon of the
diaphragm
– fibrous pericardium is attached in front to the
sternum by the sternopericardial ligaments
• Serous Pericardium:
– lines the fibrous pericardium and coats the heart.
– divided into parietal and visceral layer

5. • Parietal layer:
– lines the fibrous pericardium
– become continuous with the visceral layer of serous
pericardium
• Visceral layer:
– closely applied to the heart and is often called the
epicardium

6. The wall of the heart consists of three layers; from
superficial to deep, they are:
• Epicardium:
– a thin external layer formed by the visceral layer of
serous pericardium
• Myocardium:
– a thick middle layer composed of cardiac muscle
• Endocardium:
– a thin internal layer
– lining membrane of the heart that also covers its
valves

8. Heart
• Hollow muscular organ
• Pyramid shaped and lies within the
pericardium in the mediastinum
• Connected at its base to the great blood
vessels but otherwise lies free within the
pericardium

9. Surfaces of the Heart
• The heart has three surfaces:
– Anterior (or sternocostal)
• formed mainly by the right atrium and the right ventricle
• separated from each other by the vertical atrioventricular
groove
– Posterior (or base) – Left atrium.
– Inferior (or diaphragmatic)
• Left and right ventricles.
• separated by the posterior interventricular groove
• inferior surface of the right atrium, into which the inferior
vena cava opens, also forms part of this surface

10. • Right pulmonary – Right atrium.
• Left pulmonary – Left ventricle.
• Apex
– left ventricle
– directed downward, forward, and to the left
– lies at the level of the fifth left intercostal space

12. Borders
• There are four main borders of the heart:
• Right border – Right atrium
• Inferior border – Left ventricle and right
ventricle
• Left border – Left ventricle (and some of the
left auricle)
• Superior border – Right and left atrium and
the great vessels

14. Sulci of the Heart
• Heart is divided into four chambers.
• These divisions create grooves on the surface of
the heart – these are known as sulci.
• The coronary sulcus (or atrioventricular groove)
– runs transversely around the heart
– represents the wall dividing the atria from the
ventricles
• The anterior and posterior interventricular sulci:
– running vertically on their respective sides of the
heart.
– represent the wall separating the ventricles (R & L)

15. Pericardial Sinuses
• They are passageways formed in which the
pericardium folds around the great vessels
• The oblique pericardial sinus is a blind ending
passageway located on the posterior surface of
the heart – around large veins
• The transverse pericardial sinus is found
superiorly on the heart – around the aorta,
pulmonary trunk and the reflection around the
large veins

16. Chambers of Heart
• Right Atrium
• Consists of a main cavity and a small outpouching, the
auricle
• On the outside of the heart at the junction between
the right atrium and the right auricle is a vertical
groove, the sulcus terminalis, which on the inside
forms a ridge, the crista terminalis.
• The part of the atrium in front of the ridge is
roughened or trabeculated by bundles of muscle fibers,
the musculi pectinati, which run from the crista
terminalis to the auricle.

18. Right Ventricle
• Communicates with the right atrium through the
atrioventricular orifice
• With the pulmonary trunk through the pulmonary
orifice
• As the cavity approaches the pulmonary orifice, it
becomes funnel shaped, at which point it is referred to
as the infundibulum.
• The walls of the right ventricle are much thicker than
those of the right atrium and show several internal
projecting ridges formed of muscle bundles.
• The projecting ridges give the ventricular wall a
spongelike appearance and are known as trabeculae
carneae.

20. • The trabeculae carneae are composed of three types.
• The first type comprises the papillary muscles, which
project inward,
– being attached by their bases to the ventricular wall
– their apices are connected by fibrous chords (the chordae
tendineae) to the cusps of the tricuspid valve
• 2nd type:
– Attached to the ventricle wall at both ends (forming a
bridge)
• 3rd type:
– Attached to the ventricle wall along their length (forming a
ridge)

21. • The tricuspid valve guards the atrioventricular orifice
– consists of three cusps formed by a fold of endocardium
with some connective tissue enclosed: anterior, septal,
and inferior (posterior) cusps.
• When the ventricle contracts, the papillary muscles
contract and prevent the cusps from being forced into
the atrium and turning inside out as the
intraventricular pressure rises.
• To assist in this process, the chordae tendineae of one
papillary muscle are connected to the adjacent parts of
two cusps

24. • The pulmonary valve guards the pulmonary orifice and
consists of three semilunar cusps formed by folds of
endocardium
– curved lower margins and sides of each cusp are attached to the
arterial wall
– open mouths of the cusps are directed upward into the
pulmonary trunk
– no chordae or papillary muscles are associated with these valve
cusps
• Moderator band
– large muscular structure that runs between the interventricular
septum and the anterior wall of the right ventricle
– has an important conductive function, containing right bundle
branches (part of conducting system of heart)

25. • Interventricular Septum:
– separates the two ventricles
– made up of a membranous part (superiorly) and a
muscular part (inferiorly)
– can be located, as it spans between the anterior and
posterior interventricular grooves
• Interatrial Septum:
– two atria are separated by a solid muscular wall
– within the right atrium, the interatrial septum has a an
oval shaped depression, called the fossa ovalis
– it is the closed form of the foramen ovale (valve present in
the foetal heart.)

27. Left Atrium
• Smooth interior
• Receives oxygenated blood from the pulmonary
veins
• Forms the posterior border of the heart
• Blood is pumped from the left atrium into the left
ventricle, via the mitral valve
• Behind it lies the oblique sinus of the serous
pericardium
• The fibrous pericardium separates it from the
esophagus

29. Left Ventricle
• Receives oxygenated blood from the left atrium, and
expels it into the aorta
• Located anteriorly to the left atrium, contributing to
the anterior aspect of the heart, and forming the apex.
• Communicates with the left atrium through the
atrioventricular orifice
• With the aorta through the aortic orifice
• Walls of the left ventricle are three times thicker than
those of the right ventricle
• There are well developed trabeculae carneae, two
large papillary muscles, but no moderator band

31. Mitral Valve
• Guards the atrioventricular orifice
• Consists of two cusps, one anterior and one
posterior, which have a structure similar to that
of the cusps of the tricuspid valve
• Anterior cusp is the larger and intervenes
between the atrioventricular and aortic orifices.
• Attachment of the chordae tendineae to the
cusps and the papillary muscles is similar to that
of the tricuspid valve.

33. Aortic Valve
• Guards the aortic orifice
• Similar in structure to the pulmonary valve
• One cusp is situated on the anterior wall (right cusp)
• Two are located on the posterior wall (left and
posterior cusps).
• Behind each cusp, the aortic wall bulges to form an
aortic sinus.
• The anterior aortic sinus gives origin to the right
coronary artery
• The left posterior sinus gives origin to the left coronary
artery.

38. Blood Supply of Heart
Aorta :
• Main arterial trunk that delivers oxygenated
blood from the left ventricle of the heart to the
tissues of the body
• Divided for purposes of description into the
following parts:
• Ascending aorta, arch of the aorta, descending
thoracic aorta, and abdominal aorta.

39. • Ascending aorta:
• The right coronary artery arises from the
anterior aortic sinus
• The left coronary artery arises from the left
posterior aortic sinus

40. Right coronary artery
• Arises from the anterior aortic sinus of the
ascending aorta and
• Runs forward between the pulmonary trunk and
the right auricle
• Descends almost vertically in the right
atrioventricular groove,
• At the inferior border of the heart it continues
posteriorly along the atrioventricular groove to
anastomose with the left coronary artery in the
posterior interventricular groove.

41. • The following branches from the right coronary
artery supply the right atrium and right ventricle
and parts of the left atrium and left ventricle and
the atrioventricular septum:
– Right conus artery
– Anterior ventricular branches
– Marginal branch
– Posterior ventricular branches
– Posterior interventricular (descending) artery
– Atrial branches
– Artery of the sinuatrial node

42. Left coronary artery
• Larger than the right coronary artery
• Supplies the major part of the heart, including
the greater part of the left atrium, left ventricle,
and ventricular septum
• Arises from the left posterior aortic sinus of the
ascending aorta and passes forward between
the pulmonary trunk and the left auricle
• Enters the atrioventricular groove and divides
into an anterior interventricular branch and a
circumflex branch.

43. Branches
• Anterior interventricular (descending) branch
– Left diagonal artery
– Left conus artery
• Circumflex artery
– Left marginal artery
– Anterior ventricular
– Posterior ventricular branches
– Atrial branches