Fig 1.
(A) Cross-section of a heart from a 22-year-old with no cardiac history, who died in an automobile accident. The relatively thin free wall of the right ventricle contrasts with the more substantial muscle mass of the left ventricle's septal and free walls, which are nearly equal in size and mass. (B) Fibre orientation of the right ventricle and septum: the free wall consists primarily of transverse fibres, while the septum contains helical or oblique fibres, allowing the septum to twist and shorten while the free wall constricts.354 (Reprinted from Allen et al.,328 with permission from Oxford University Press). LV: left ventricle; RV: right ventricle.