The comparative investigation of morphology of papillary muscles of left ventricle in different species.

The papillary muscles of the heart are conical projections into the respective chamber of myocardium covered by endocardium. Functionally, the papillary muscles are important part of the respective valve complex. They prevent the cusps of a valve from being everted when the ventricle contracts. Our study was conducted on papillary muscles in left ventricle of 135 normal adult hearts (20 humans, 25 dogs, 60 sheep and 30 goats). The length (L), width (W), head number (HN), angle with ventricular wall (A degrees ), distance with annulus (AnD) and apex (ApD), and the shapes of the anterior and posterior papillary muscles were observed. The tendinous chords (CTN) attached to each papillary muscle were counted at their origin. The values of both anterior and posterior papillary muscles were not statistically significant (p > 0.05) in measurements of L, W, HN, A degrees and AnD of all species, but those of CTN and ApD were significant (p < 0.05) between human and animal hearts, while the difference was not significant (p > 0.05) between sheep and goat hearts. Knowledge of morphology of papillary muscles in different species will be of much use to clinical investigators in their studies.