Heart Anatomy: Borders and Structures

Heart Structure and Borders

• The heart has a hollow muscular structure, approximately the size of a hand fist.
• It has a base directed upwards and to the right, and an apex directed downwards and to the left.
• External features of the heart include sulci (grooves), borders, surfaces, and mapping on the chest wall.

Sulci (Grooves) of the Heart

• Coronary sulcus (Atrio-ventricular groove): separates the atria from the ventricles.
• Anterior and posterior inter-ventricular sulci: separate the two ventricles anteriorly and posteriorly.

Borders of the Heart

• Superior border: along which arise the great vessels of the heart.
• Inferior border: slightly concave and consists mainly of the right ventricle.
• Right border: convex and is formed by the right atrium.
• Left border: convex and is formed by the left ventricle.

Surfaces of the Heart

• Sterno-costal (Anterior) surface: formed of the right atrium, right ventricle (2/3 of ventricular surface), and left ventricle (1/3 of ventricular surface).
• Diaphragmatic (Inferior) surface: formed of the right ventricle (1/3 of ventricular surface) and left ventricle (2/3 of ventricular surface).
• Base (Posterior surface): formed of the left atrium.

Interior of the Right Atrium

• Anterior wall: shows a series of horizontal muscular ridges (musculi pectinati) arising from a vertical ridge (crista terminalis).
• Posterior wall: formed of the interatrial septum, showing an oval depression (fossa ovalis) surrounded by a curved margin (limbus fossa ovalis).
• Orifices in the right atrium:
  • Superior vena caval opening
  • Inferior vena caval opening
  • Coronary sinus
  • Right atrio-ventricular (Tricuspid) orifice

Interior of the Right Ventricle

• Inflow part: shows muscular ridges (trabeculae carneae) and papillary muscles (pyramidal in shape) projecting from these ridges.
• Outflow part (infundibulum): funnel-shaped, smooth, non-muscular, leading upwards to the pulmonary orifice.
• Orifices in the right ventricle:
  • Tricuspid orifice
  • Pulmonary orifice

Interior of the Left Atrium

• Forms the base of the heart
• Walls are smooth
• Receives the orifices of the 4 pulmonary veins

Interior of the Left Ventricle

• Thicker wall than the right ventricle
• Inflow part: characterized by more trabeculae carneae than the right ventricle and shows papillary muscles
• Outflow part (aortic vestibule): smooth and fibrous
• Orifices in the left ventricle:
  • Mitral orifice
  • Aortic orifice

Arterial Supply of the Heart

• Right coronary artery:
  • Gives marginal artery
  • Gives posterior interventricular artery
• Left coronary artery:
  • Gives anterior interventricular artery
  • Gives circumflex artery

Venous Drainage of the Heart

• Coronary sinus: a wide venous channel in the posterior part of the coronary sulcus, ending in the right atrium.

Cardio-Vascular System (CVS)

• Includes:
  • Heart
  • Blood vessels (arteries, veins, and capillaries)
  • Lymphatic system