Heart 8 around the two ventricles and proceeding toward the apex. This complex swirling pattern allows the heart to pump blood more effectively. There are two types of cells in cardiac muscle: muscle cells which have the ability to contract easily, and pacemaker cells of the conducting system. The muscle cells make up the bulk (99%) of cells in the atria and ventricles. These contractile cells are connected by intercalated discs which allow a rapid response to impulses of action potential from the pacemaker cells. The intercalated discs allow the cells to act as a syncytium and enable the contractions that
Lateral ventricles floor is formed by the fimbria hippocampi (from which the fornix emerges), and then, more anteriorly, by the hippocampus itself. As with the posterior horn, the remainder of the boundary - in this case the lateral side of the floor - is directly in contact with the white matter of the surrounding lobe. During development, pressure from exterior structures causes a number of concave bulges to form within the lateral ventricles, which can be extremely variable in their degree of development; in some individuals they are ill-defined, while in others they can be prominent: Between the inferior horn and the