Morphology of the papillary muscles and the chordae tendineae of the ventricles of adult human hearts

Introduction: The papillary muscles (PM) play a vital role in atrioventricular (AV) valve function. The PM and their chordae tendineae (CT) regulate the closure of the AV valve during systole. The present study was undertaken to categorize the PM based on their shapes and variant patterns and CT based on their types and the branching pattern. Methods: This study included formalin-fixed ten adult cadaveric heart specimens. We observed the number, shape, length, breadth, pattern, and presence of extra PM. The number of chordae attached to the tip of each PM was quantified. We classified the types and branching patterns of the chordae and their pattern of attachment to the cusps. Results: In the right ventricle, conical, truncated, and flat-topped PM were observed. The anterior PM had 5.3 ± 1.9, the posterior PM had 2.7 ± 2.1, and the septal PM had 3.5 ± 2.3 CT attached to it. In the left ventricle, we observed conical, truncated, flat-topped, bifurcate, and trifurcate shapes of PM. The anterior and the posterior PM had 7.7 ± 2.8 and 7.7 ± 2.7 CT attached to them, respectively. The true CT were cusp, cleft, and commissural and the false CT were pillar-wall, inter-pillar, and strut. We also found 3 branching patterns for the chordae (single, fan-shaped, and web forming). Conclusion: The study explored the comparative morphology of PM and chordae in the right and left ventricles. The knowledge of the morphological pattern of PM and CT would contribute to the valvular function and aid in diagnosing conditions such as valve prolapse or regurgitation.