Change: There were only format changes (bold, italics, etc.) in this version. See this version for details. (Word count: 1136)

Change: There were only format changes (bold, italics, etc.) in this version. See this version for details. (Word count: 1130)

Change: There were only format changes (bold, italics, etc.) in this version. See this version for details. (Word count: 1130)

Change: Is a Thinthin double walled sac that surrounds the heart and contains the roots of the great vessels it characterizedis characterised by two layers. The first layer is an outer fibrous pericardium which anchors the heart to the surrounding structures. The second layer is   View changes from previous version. (Word count: 855)

Change: The heart is a muscular organ in all vertebrates responsible for pumping blood through the blood vessels by repeated, rhythmic contractions Pericardium A Thin double walled sac that surrounds the heart and contains the roots of the great vessels it characterized by two layers. The first layer   View changes from previous version. (Word count: 670)

Change: Chambers: ChambersThe Heart externally is composed of four hollow chambers. Two smaller atria and two larger ventricles. Atria (Atrium) Thin-walled chambers located superiorly The anterior part of each atrium is a wrinkled, flap-like extension called the auricle Separated from ventricles externally by deep   View changes from previous version. (Word count: 642)

Change: The diaphragmatic attachment consists of loose fibrous tissue, which can be easily broken down, unlike the fused portion of the sac. Above, the fibrous pericardium not only blends with the external coates of the great vessels, but is continuous with the pretrachael layer of the deep cervical fascia. It   View changes from previous version. (Word count: 640)