EXTERNAL FEATURES OF HEART

Dr. Gurudasan28.04.14

INTRODUCTION Heart is a four

chambered muscular pump present in the middle mediastinum.

Heart is obliquely placed.

2/3rd of it lies on the left side and 1/3rd lies on the right side at an angle of 45° with the saggital plane.

Median plane

EXTERNAL FEATURESThe average size of

the heart is of that of a clenched fist of the person.

Average weight: 280gm

Heart contains upper atrial/venous chambers and lower ventricular/arterial chambers.

Atria and ventricles are seperated by coronary sulcus externally.

Left atrium

Leftventricle

Right ventricle

Rightatrium

Coronary sulcus

SURFACES OF HEARTSterno-costal / anterior surface:

It is directed forwards and upwards.

It is formed byI) Ant. Surface of Right

atrium & AuricleII) A part of Lt.auricleIII) Ant. Surface of

right ventricle (2/3rd) IV) Ant. Surface of left

ventricle (1/3rd) Sterno-costal surface

Relations of sterno-costal surface:

Ant: Posterior surface of body of sternum, 3rd to 6th costal cartilages of both sidesAnterior margins of both lungs pleura

Cardiac dullness:On the left 4th costal cartilage, the pericardium comes in direct contact with body of sternum due to cardiac notch on left lung is dull on percussion.The dullness overlies the anterior surface of right ventricle.

Costal cartilages

SURFACES OF HEARTDiaphragmatic / Inferior surface:

o It is flat and faces upwards and backwards.

o It is formed only by two ventricles.

o 2/3rd – Left ventricle

o 1/3rd – Right ventricle

o It lies over the central tendon of diaphragm.

Diaphragmatic surface

SURFACES OF HEARTLeft surface:It is directed

upwards, backwards and to the left.

Formed mainly by left ventricle and partly by left atrium and its auricle. Left surface

BASE OF HEARTIt is also called

as posterior surface.

It is the most fixed part and is quadrilateral in outline.

It is formed by both atria

2/3rd – Left atrium1/3rd – Right

atriumBase of the heart

BASE OF HEARTBoundaries:Above: bifurcation

of pulmonary trunk

Below: Posterior part of atrio-ventricular groove

Right side: Right border of right atrium

Left side: Left border of left atrium

Pulmonary trunk

Left border of left atrium

Atrio-ventricular groove

Right border of Right atrium

APEX OF THE HEARTIt is the conical

area formed only by left ventricle

It is directed downwards, forwards and to the left in left 5th ICS about 9cm from midline (Apex beat).

In new born apex beat is felt at Lt. 4th ICS.Apex of the heart

BORDERS OF HEARTRight border:Formed only by right atrium.

It is rounded and convex.

It extends from SVC to IVC.

It has shallow vertical groove extending from SVC to IVC.

It seperates Base from sterno-costal surface.

Right border

SVC

IVC

Sternocostal surface

BORDERS OF HEARTInferior border: It is sharp and

extends from IVC to apex of the heart.

Closer to the apex it contains a notch called incisura apicis cordis.

Inferior border

IVCApex

incisura apicis cordis

Sternocostal surface

BORDERS OF HEARTLeft border:It is ill definedIt extends from

left auricle to the apex of heart.

It seperates sterno-costal surface from left surface.

Left border

Left Aurice

Apex

DEMARCATIONS Heart is externally

demarcated by many gooves.

Atrio-ventricular groove:It surrounds the heart but deficient in front due to pulm.trunk.It consists of anterior and posterior part.Anteriorly right side it contains right coronary artery, left side – circumflex br of left coronary artery, termination of great cardiac vein and commencement of coronary sinus.

Atrio-ventricular groove

Right coronary artery

Circumflexartery

Posterior part of the atrio-ventricular groove intervene between the base and diaphragmatic surface.

It contains coronary sinus and anastomosis of right and left coronary arteries.

Atrio-ventricular groove

Coronary sinus

Anterior interventricular groove:

It runs downwards, forwards and parallel to left border and meets the inferior border at the incisura apicis cordis.

It indicates the anterior attachment of interventricular septum

It lodges anterior interventricular artery, a branch from left coronary artery and great cardiac vein.Anterior interventricular artery

Great cardiacvein

Posterior interventricular groove:

It runs forwards along the posterior surface and meet the incisura apicis cordis.

It indicates the posterior attachment of interventricular septum

It lodges posterior interventricular branch of right coronary artery and middle cardiac vein.

posterior interventricular artery

Middle cardiac vein

CRUX OF THE HEARTIt is the meeting

point of interatrial, posterior interventricular and posterior part of atrioventricular groove.

Inter atrial groove

Posterior Interventricular groove

Posterior part of atrioventricular goove

OTHER POINTS OF INTERESTHeart presents some only structures:I) Apex – only formed by left ventricleII) Base – only formed by two atriaIII) Right border – only formed by right atriumIV) Diaphragmatic surface – only formed by

ventricles.2/3rd and 1/3rd features:I) 2/3rd of base is by left atrium, 1/3rd by right

atriumII) 2/3rd of diaphragamtic surface is formed by left

ventricle and 1/3rd by right ventricleIII) 2/3rd of sterno-costal surface is formed by right

ventricle and 1/3rd by left ventricleIV) 2/3rd of entire heart is left to the medial plane

and 1/3rd is right to the median plane.

CLINICAL ANATOMY

Clinical base of the heart: It is represented by a line extending from the aortic auscultatory area in the Rt II ICS to pulmonary area in the left II ICS.

Follow your heart, but takeyour brain with you to choose the best person.