Location of the heart

Anatomy of the heart

The heart is about 12cm long, 9 cm wide at its broadest point and 6cm thick which has an average mass of 250g in adult female and 300g in adult male. The heart rests on the diaphragm, near the midline of the thoracic cavity and lies in the mediastinum. Mediastinum is an anatomical region from sternum to the vertebral column. The heart is also located between the lungs in the middle of the chest, behind and slightly to the left of the sternum and in front of the spine. Because the heart is not central, but lies to the left of the center line, the heart beat is best felt on the left side of the chest. To make room for it, the left lung is rather smaller than the left.

The pointed apex is formed by the tip of the left ventricle and rests on the diaphragm. It is directed anteriorly, inferiorly, and to the left. The base of the heart is its posterior surface. It is formed by the atria of the heart, mostly the left atrium. 

In addition to the apex and base, the heart has several distinct surfaces and borders. The anterior surface is deep to the sternum and ribs. The inferior surface is the part of the heart between the apex and right border and rest mostly on the diaphragm. The right border faces the right lung and extends from the inferior surface to the base. The left border, also called the pulmonary border, faces the left lung and extends from the base to the apex.

Pericardium of the Heart

The membrane that surrounds and protects the heart is the pericardium. It confines the heart to its position in the mediastinum, while allowing sufficient freedom of movement for vigorous and rapid contraction. The pericardium consists of two part, the fibrous pericardium and the serous pericardium. The superficial fibrous pericardium is composed of tough, inelastic, dense irregular connective tissue. It resembles a bag that rests on the attaches of the diaphragm, its open end is fused to the connective tissues of the blood vessels entering and leaving the heart. The fibrous pericardium prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum. 

The deeper serous pericardium is a thinner, more, delicate membrane that forms a double layer around the heart. The outer parietal layer of the serous pericardium is fused to the fibrous pericardium. The inner visceral layer of the serous pericardium, also called the epicardium, is one of the layers of the heart wall and adheres tightly to the surface of the heart. Between the parietal and visceral layers of the serous pericardium is a thin film of lubricating serous pericardial fluid, reduces friction between the layers of the serous pericardium as the heart moves. The space that contains the few milliliters of the pericardial fluid is called the pericardial cavity.

Source: http://www.cvtsa.com/si55550728HeartAnatomyAnterior_frontview/M-441-202.html