Describe the location and dimensions of Heart.
Location of heart: Heart lies in the middle mediastinum. 1/3rd of the heart lies to the right and 2/3rd to the left of the midline. It lies opposite to T5 – T8 vertebrae in supine position & T6 – T9 vertebrae in erect position.
Dimensions of heart: Base to apex-12cm; Transversely- 8-9cm; Anteroposteriorly- 6cm.
Weight: In males it weighs: 280-340 gm and in females : 230-280 gm
Describe the external features of Heart.
The heart has:
An apex
- It is formed by the left ventricle.
- It lies in the fifth intercostal space 9 cms. from the median plane.
Three surfaces
- Sternocostal surface: Is formed by right atrium, right ventricle, left auricle and left ventricle.
- Left surface: Is formed by left auricle and left ventricle.
- Diaphragmatic surface: 2/3rd is formed by left ventricle and 1/3rd by right ventricle.
- Posterior surface/Base: It is quadrilateral in shape.
- 2/3rd of base is formed by posterior surface of left atrium and 1/3rd by right atrium.
- It lies opposite to T5-T8 vertebra in supine position.
Four borders
- Superior: is formed by the two atria.
- Right: Right atrium
- Inferior: Mainly by right ventricle and near the apex by left ventricle.
- Left: Is formed by left auricle and left ventricle.
Five sulci
- Atrioventricular sulcus (coronary sulcus): separates atria from ventricles.
- Anterior interventricular sulcus: separates right and left ventricles on the sternocostal surface.
- Posterior interventricular sulcus: separates right and left ventricles on the diaphragmatic surface.
- Interatrial sulcus: Separates right atrium from the left atrium .
- Sulcus terminalis: extends from the opening of superior vena cava to inferior vena cava and separates the rough part from the smooth part of the right atrium.
What are the posterior relations of base of Heart?
Following are the posterior relations of the Base of heart:
- Oblique sinus of pericardial cavity
- Right pulmonary veins
- Oesophagus
- Descending thoracic aorta
- Middle four thoracic vertebrae
Applied Aspects
Apex beat
Is the lowermost and outermost thrust of the heart, felt on the front of the chest. In adults it is felt in the left 5th intercostal space 9cm. from the median plane (just medial to the midclavicular line). In infants it is felt in the 3rd intercostal space just lateral to the midclavicular line.
Dextrocardia
It is a congenital anomaly in which the heart lies on the right side of the thoracic cavity. This may be associated with the reversal of all the abdominal organs, a clinical condition known as situs inversus.