EXTERNAL MORPHOLOGY -

• Auricle 2 in number at broad area.
• Both are small, flap like cover ventricles like caps i.e. auricular appendix. It's skeleton is made up of musculo-pelati.
• Ventricles 2, large at apex area.
• Left ventricle is comparatively large and covers complete apex.
• Right ventricle does not reach the apex.
• Both ventricles are separated by a groove ventricular sulcus externally here caronary artery present that supply blood to complete heart.
• Auricles are demarkated externally from ventricle by coronary sulcus.
• 1 pre caval and 1 post caval open in right auricles. (In cat pre cavals are absent) In rabbit 2 pre cavals present.
• In L.A. 2 pairs pulmonary veins open. (In rabbit one pair)
• In broad area left carotico systemic arch and pulmonary aorta (total 3) present.
• All veins open in auricles. All arteries originate from ventricles.