External features of Heart

PericardiumPericardium is a fibroserous sac that encloses the heart and roots of the great vessels.

Relations of Pericardium: Anterior: Body of Sternum2nd to 6th costal cartilages Posterior: 5th to 8th thoracic vertebrae

Layers of the Pericardium1. Fibrous Pericardium Attached anteriorly to the sternum by Sternopericardial ligaments.

2. Serous Pericardium Two Layers:

a. Parietal b. Visceral

Serous Pericardium

Coverings & Wall of the Heart

The lines of reflection between visceral and parietal pericardium form two pericardial sinuses, the transverse pericardial sinus and the oblique pericardial sinus. The transverse pericardial sinus lies anterior to the superior vena cava and posterior to the ascending aorta and pulmonary trunk.The oblique pericardial sinus lies posterior to the heart in the pericardial sac.

Pericardial Sinuses

Pericardial Sinuses

1. Fibrous Pericardium and Parietal layer of serous Pericardium:

By Phrenic nerves 2. Visceral layer of Serous Pericardium:

By Sympathetic trunk and vagus nerves

Nerve supply of the Pericardium

Location of the Heart

Angle of LouisIt is the angle at which the manubrium and sternum meet/articulate. It is an anatomical landmark for finding the second rib, approx. area of the carina

Location of Heart

• It lies in the middle mediastinum.

• The Heart is somewhat pyramidal in shape, having:

• Apex• Sterno-costal (anterior

surface)• Base (posterior surface).• Diaphragmatic (inferior

surface)• It consists of 4 chambers, 2

atria (right& left) & 2 ventricles (right& left)

Location of the Heart

Heart (Anterior Surface)

Anterior Surface

Heart (Posterior and inferior surfaces)

Base

Inferior Surface

Borders of the HeartBorders of the HeartRight border: formed by right atrium Left border: formed by left auricle and left ventricleLower border: formed by right atrium & mainly by right ventricle + apical part of left ventricleUpper border: Is formed by the 2 atria

Surfaces of the HeartSternocostal surface (Anterior surface):Mainly formed by right atrium and right ventricle.

Diaphragmatic surface (Inferior surface):Mainly formed by right and left ventricles. Small portion is formed by right atrium.

Base (Posterior surface):Mainly formed by left atrium.

Apex: formed by left ventricle

Apex of the heart

• Directed downwards, forwards and to the left.

• It is formed by the left ventricle.

• lies at the level of left 5th intercostal space 3.5 inch from midline.

Note that the base of the heart is called the base because the heart is pyramid shaped; the base lies opposite the apex. The heart does not rest on its base; it rests on its diaphragmatic (inferior) surface

Sterno-costal (anterior)surface• Divided by coronary (atrio-

ventricular) groove into : Atrial part, formed mainly by right

atrium. Ventricular part , the right 2/3 is

formed by right ventricle, while the left l1/3 is formed by left ventricle.

The 2 ventricles are separated by anterior interventricular groove, which lodges :

Anterior interventricular artery (branch of left coronary).

Great cardiac vein.

The coronary groove lodges right coronary artery.

This surface is formed mainly by the right atrium and the right ventricle.

Diaphragmatic (Inferior)surface Formed by the 2-ventricles, mainly left ventricle (left 2/3). Slightly concave as it rests on diaphragm. Directed inferiorly & backward.Separated from base of heart by posterior part of coronary sulcus.The 2-ventricles are separated by posterior interventricular groove which lodges:Posterior interventricular artery Middle cardiac vein

Base of the Heart (posterior surface)

It is formed by the 2 atria, mainly left atrium, into which open the 4 pulmonary veins.It is directed backwards.Lies opposite middle thoracic vertebrae (5-7). Is separated from the vertebral column by descending aorta, esophagus and oblique sinus of pericardium. Bounded inferiorly by post. part of coronary sulcus , which lodges the coronary sinus.

Left atrium

Heart (Anterior view)

SVC

AA PT

RV LV

IVC

RA

SVC: Superior vena cava

AA: Ascending Aorta

PT: Pulmonary Trunk

RA: Right Auricle

RV: Right ventricle

LV: Left ventricle

IVC: Inferior vena cava

Heart (Posterior view)

LA RA

LV IVC

LA: Left auricle

RA: Right auricle

LV: Left ventricle

IVC: Inferior vena cava

Heart (Posterior view)

Heart (Anterior interventricular Sulcus or Groove)

AIS

PIS

CS

Heart (Posterior interventricular Sulcus or Groove)Coronary or Atrioventricular Sulcus or Groove