Final answer:
The anulus fibrosus forms the annuli fibrosi rings, providing structural support for heart valves. Atrioventricular valves are supported by chordae tendineae and papillary muscles, while semilunar valves operate based on pressure changes. The myocardium's complex muscle pattern enables efficient blood pumping.
Step-by-step explanation:
The anulus fibrosus serves a crucial function in the structure and operation of the heart by forming the annuli fibrosi, which are fibrous rings that hold the heart valves in place. In the human spine, the anulus fibrosus is the tough, fibrous outer portion of an intervertebral disc. However, in the context of cardiology, it refers to the structure forming the fibrous rings that anchor the heart valves and ensure their proper function.
The heart valves control blood flow through the heart's four chambers. In particular, the atrioventricular valves (tricuspid and mitral) are supported by chordae tendineae and papillary muscles, which prevent the valves from inverting. In contrast, the semilunar valves (aortic and pulmonary) lack these supporting structures, as they are made of pocket-like folds of endocardium and are secured by the pressure of blood itself when the ventricles relax.
The myocardium is the middle layer of the heart, consisting of cardiac muscle cells structured in a complex pattern to optimize the heart’s pumping efficiency. This intricate arrangement of muscle cells emphasizes the heart's sophistication and its reliance on the robust framework provided by structures like the annulus fibrosus and annuli fibrosi.