Heart

 

short note

 • superior venacava

 • transverse sinus of heart

 • arch of aorta

 • pericardial sinus

 • coronary siniuse

 • pericardium

 • Surfaces of the Heart

 A. Pericardium:-

 • The pericardium is a fibroserous sac which encloses the heart and the roots of the great vessels.

 • It is situated in the middle mediastinum.

 • It consists of the two layers fibrous pericardium and the serous pericardium.

FIBROUS PERICARDIUM:-

Fibrous pericardium is a conical sac made up of fibrous tissue.

 • Its apex is blunt ,and fused with roots of great vessels and with pretracheal fascia.

 • its base is broad ,and attached with central tendon of diaphragam.

 • Anteriorly, it is connected to the upper and lower ends of body of the sternum by superior and inferior sternopericardial ligaments .

 • Posteriorly, it is related to the principal bronchi, the oesophagus with the nerve plexus around it and the descending thoracic aorta.

 • On each side, it is related to the mediliastinal pleura, the mediastinal surface of the lung, phrenic nerve, and the pericardiacophrenic vessels.

 • *It protects the heart against sudden overfilling and prevents over expansion of the heart.

SEROUS PERICARDIUM :-

 • It is thin, double-layered serous membrane lined by mesothelium.

 • The outer layer or parietal pericardium is fused with the fibrous pericardium.

 • The inner layer or the visceral pericardium, or epicardium is fused to the heart, except along the cardiac grooves, where it is separated from the heart by blood vessels.

 • pericardial cavity is a potential space between the parietal pericardium and the visceral pericardium. It contains serous fluid which lubricates and allows the heart to beat smoothly.

Contents of the Pericardium

 1. Heart with cardiac vessels and nerves.

 2. Ascending aorta.

 3. Pulmonary trunk.

 4. Lower half of the superior vena cava.

 5. Terminal part of the inferior vena cava

 6. The terminal parts of the pulmonary veins.

 B. pericardial sinus

(Sinuses of Pericardium):-

There are two pericardial sinus :-

transverse sinus of heart

 • The epicardium at the roots of the great vessels is arranged in form of two tubes.

 • The arterial tube encloses the ascending aorta and the pulmonary trunk at the arterial end of the heart tube, and

 • the venous tube encloses the venae cavae and pulmonary veins at the venous end of the heart tube.

 • The passage between the two tubes is known as the transverse sinus .

 *. on each side, it opens into the general pericardial cavity.

 *. It develops from degeneration of the central part of dorsal mesocardium.

oblique sinus :-

 • The oblique sinus is a narrow gap behind the heart

 • lt is bounded anteriorly by the left atrium, and posteriorly by the parietal pericardium and oesophagus.

 • The oblique sinus permits pulsations of the left atrium to take place freely.

 • lt develops due to rearrangement of veins at the venous end.

Nerve Supply :-

 1. phrenic nerves :- It supplies fibrous and parietal pericardia .

 2. autonomic nerves of the heart :- It supply epicardium.

 C. Surfaces of the Heart :-

 Heart has three suraface

 1. anterior or sternocostal surface :-

 • it is formed mainly by the right atrium and right ventricle, and partly by the left ventricle and left auricle.

 • Most of the sternocostal surface is covered by the lungs, but a part of it that lies behind the cairdiac notch of the left lung is uncovered. this area is called area of superficial cardiac dullness.

 2. inferior or diaphragmatic surface:-

 • it rests on th e central tendon of the diaphragm.

 • it is formed in its left 2/3 by the left ventricle, and in its right 1/3 by the right ventricle.

 3. left surface:-

 • it is formed mostly by the left ventricle, and at the upper end by the left auricle.

 • in its upper part, the surface is crossed by the coronary sulcus.

 D. RIGHT ATRIUM :-

 Developmental Components

 1. Smooth posterior part--

 --- Absorption of right horn of sinus venosus

 2. Rough anterior part---atrial chamber proper.

 3. Demarcating part---crista terminalis

Internal structure of Right Atrium

The interior of the right atrium can be broadly divided into the three parts:

Smooth Posterior Part or Sinus Venarum

 1. Developmentally, it is derived from the right horn of the sinus venosus.

 2. tributaries or opening of right atrium

 a. superior vena cava opens at the upper end.

 b. inferior vena cava opens at the lower end

 • The opening of inferior vena cava is guarded by a rudimentary valve called eustachian valve.

 c. coronary sinus opens between the opening of the inferior vena cava and the right atrioventricular orifice.

 • this opening is guarded by the valve of the coronary sinus or thebesian valve

 d. numerous venae cordis minimae

 open into the right atrium through small forarnina

 3. intervenous tubercle of Lower :- It is very small projection on wall of right atrium just below the opening of superior vena cava.

Rough Anterior Part or Pectinate Part:-

 1. Developmentally, it is derived from the primitive atrial chamber.

 2. It presents a series of transverse muscular ridges called musculi pectinati , it gives apperance of teeth of comb.

lnteratrial Septum:-

 1. Developmentally, it is derived from the septum primum and septum secundum.

 2. It presents the fossa ovalis and annulus ovalis

 3. The remains of the foramen ovale are occasionally present.

ARTERIES SUPPLYING THE HEART

The heart is supplied by two coronary arteries,- right and left coronary arteries arising from the ascending aorta. Both arteries run in the coronary sulcus.

Patent foramen ovale (PFO) is a hole between the left and right atria (upper chambers) of the heart. This hole exists in everyone before birth, but most often closes after being birth. If it fails to close naturally after a baby is born, it is called PFO.

A patent foramen ovale (PFO) means the foramen ovale did not close properly at birth.

Tetralogy of Fallot (TOF) is a type of heart defect present at birth.

It is a combination of four congenital abnormalities.i.e.

 • ventricular septal defect (VSD),

 • pulmonary valve stenosis,

 • a misplaced aorta and a

 • thickened right ventricular wall (right ventricular hypertrophy).

CARDIAC DOMINANCE :-

The artery giving the posterior interventricular branch is the dominant artery.

 • Mostly, the right coronary gives posterior interventricular artery. Such hearts are right dominant heart.

 • In 10% case, circumflex artery (branch of left coronary ) gives posterior interventricular . Such hearts are left dominant heart.

Developmental origin of Inter-atrial septum

 • Septum primum- fossa ovalis.

 • Septum secundum-limbus fossa ovalis

Tachycardia

Rapid pulse or increased heart rate (over 100 beats per minute)is called tachycardia .

 E. RIGHT CORONARY ARTERY

ORIGIN

 It arises from the anterior aortic sinus of ascending aorta.

Course

 1. It first passes forwards and to the right between root of pulmonary trunk and right auricle.

 2. It then runs downwards in the right anterior coronary sulcus.

 3. It winds round the inferior border to reach the diaphragmatic surface to reach the posterior interventricular groove.

 4. It terminates by anastomosing with the circumflex branch of left coronary artery.

Branches

 1. Atrial branches :- they are anterior, posterior and lateral. One of the anterior atrial branches is called SA nodal artery.

 2. Right conus artery:- It forms an arterial circle around pulmonary trunk with a similar branch from the left coronary artery. The circle is called, "annulus of Vieussens"

 3. Ventricular branches:- they are as anterior and posterior group.

 • The anterior group lies on the sternocostal surface

 • posterior group traverses the diaphragmatic surface of the heart.

 4. Right marginal artery:- they arises as the right coronary artery crosses the right border of heart. It runs along its inferior border till the apex of heart.

 5. Posterior interventricular branch:- they arises close to the crus of heart and lies in the posterior interventicular groove.

 • It gives septal branches to posterior 1/3rd of interventricular septum .

 • It also supplies AV node.

Area of Distribution /AREA SUPPLY

 1. Right atrium

 2. Ventricles

 • Greater part of the right ventricle, except the area adjoining the anterior interventricular groove

 • A small part of the left ventricle adjoining the posterior interventricular groove.

 3. Posterior 1/3rd part of the interventricular septum.

 4. Whole of the conducting system of the heart except a part of the left branch of the AV bundle.

 F. LEFT CORONARY ARTERY

ORIGIN

 It arises from the left posterior aortic sinus of ascending aorta.

COURSE

 1. The artery first runs forwards and to the left between the pulmonary trunk and the left auricle. Here it gives the anterior interventricular branch. The further continuation of the left coronary artery is called the circumflex artery.

 2. After giving off the anterior interventricular branch, the artery runs to the left in the left anterior coronary sulcus.

 3. It winds round the left border of the heart and continues in the left posterior coronary sulcus.

 4. Near the posterior interventricular groove, it terminates by anastomosing with the right coronary artery.

BRANCHES

 1. Anterior interventricular branch :-lt gives following branches:

 • Anterior ventricular branches , The large branch is called "left diagonal artery"

 • Septal branches

 • Left conus artery :- it forms an arterial ring around the pulomonary trunk with a similar branch from right coronary artery.

 2. Circumflex branch

 It is the terminal part of left coronary artery. Its branches are:

 • Left marginal artery which lies along the left border of heart till the apex of heart.

 • Anterior and posterior ventricular branches

 • Atrial branches which are in anterior, posterior and lateral groups.

AREA OF DISTRIBUTION:-

 1. Left atrium

 2. Ventricles

 • Greater part of the left ventricle, except the area adjoining the posterior interventricular groove

 • A small part of the right ventricle adjoining the anterior interventricular groove.

 3. Anterior part of the interventricular septum

 4. A part of the left branch of the AV bundle.

 G. Superior venacava:-

 • Superior vena cava is a large vein which collects blood from the upper half of the body and drains it into the right atrium.

 • It is formed by the union of the right and left brachiocephalic or innominate veins behind the lower border of the first right costal cartilage close to the sternum.

 • Each brachiocephalic vein is formed by the union of the internal jugular and subclavian veins.

COURSE

 • The superior vena cava is about 7 cm long.

 • It begins behind the lower border of the first right costal cartilag close to sternum.

 • pierces the pericardium at the second right costal cartilage

 • and terminates by opening into the right atrium behind the third right costal cartilage.

RELATIONS

 1. Anterior

 • Chest wall

 • Internal thoracic vessels.

 • Anterior margin of the right lung and pleura

 • The vessel is covered by pericardium in its lower half

 2. Posterior

 • Trachea and right vagus

 • Root of right lung

 3. Medial

 • Ascending aorta.

 • Brachiocephalic artery.

 4. Lateral

 • Right phrenic nerve with accompanying vessels.

 • Right pleura and lung

TRIBUTARIES

 1. azygos vein , opens into the superior vena cava at the level of the second costal cartilage

 2. Several small mediastinal and pericardial veins drain into the vena cava.

ARCH OF THE AORTA :-

 • Arch of the aorta is the continuation of the ascending aorta.

 • It is situated in the superior mediastinum behind the lower half of the manubrium sterni.

COURSE

 • It begins behind the upper border of the second right sternochondral joint

 • It runs upwards, backwards and to the left across the left side of the bifurcation of trachea.

 • it passes downwards behind the left bronchus and on the left side of the body of the fourth thoracic vertebra.

 • It ends at the lower border of the body of the fourth thoracic vertebra by becoming continuous with the descending aorta.

Thus the beginning and the end of arch of aorta are at the same level, although it begins anteriorly and ends posteriorly.

RELATIONS:-

Anteriorly and to the Left

 1. Four nerves from before backwards:

 • Left phrenic

 • lower cervical cardiac branch of the left vagus.

 • Superior cervical cardiac branch of left sympa thetic chain

 • Left vagus

 2. Left superior intercostal vein

 3. Left pleura and lung.

 4. Remains of thymus.

Posteriorly and to the Right

 1. Trachea

 2. Oesophagus

 3. Left recurrent laryngeal nerve

 4. Thoracic duct

 5. Vertebral column

Superior

 1. Three branches of the arch of the aorta:

 • Brachiocephalic

 • Left common carotid

 • Left subclavian arteries

Inferior

 1. Bifurcation of the pulmonary trunk

 2. Left bronchus

 3. Ligamentum arteriosum

 4. Left recurrent laryngeal nerve

BRANCHES

 1. Brachiocephalic artery which divides into the right common carotid and right subclavian arteries

 2. Left common carotid artery

 3. Left subclavian artery.

Coronary Sinus :-

 • The coronary sinus is the largest vein of the heart.

 • It is situated in the left posterior coronary sulcus.

 • It is about 3 cm long.

 • It ends by opening into the posterior wall of the right atrium

 • It receives the following tributaries:-

 a. The great cardiac vein

 b. The middle cardiac vein

 c. The small cardiac vein

 d. The posterior vein of the left ventricle

 e. The oblique vein of the left atrium of Marshall.

 f. The right marginal vein