Left Auricle & Ventricle

The left auricle, thicker than the right, helps to form the left side and back of the base of the heart, only its auricular appendix being visible anteriorly, upon the left of the pulmonary artery, 1903. From 'Surgical Anatomy: The Treatise of the Human Anatomy and Its Applications to the Practice of Medicine and Surgery, Volume III' (1903). The left ventricle is longer than the right, its cavity is narrower and more nearly circular in section, it forms the apex, consitutes mos of the posterior surface of the heart, and its walls are three times as thick as those of the right ventricle; its walls are thickest near the base and thinnest at the apex, near which rupture of the heart most often occurs. (Photo by VintageMedStock/Getty Images)