The medial papillary muscle complex and its related septomarginal trabeculation. A normal anatomical study on human hearts
Restivo, A.; Smith, A.; Wilkinson, J.L.; Anderson, R.H.
Journal of Anatomy 163: 231-242
1989
ISSN/ISBN: 0021-8782 PMID: 2606775 Document Number: 341266
The morphology of the medial papillary muscle complex of the right ventricle was studied in 81 normal human hearts from subjects ranging in age from 20 weeks of gestation to 13 months. The position of the main medial papillary muscle (of Lancisi) was differentiated in terms of a root and a belly. The anterior aspect of the root was found in a constant position at the basal bifurcation of the septomarginal trabeculation. The belly showed considerable positional variation. Three groups of minor papillary muscles were identifed and localised in specific areas in the base of the right ventricle. They formed part of the medial papillary complex, which was constantly related to the anteroseptal commissure of the tricuspid valve. A separate group of papillary muscles were identified on the inlet portion of the septum. The anterosuperior and posterior portions of the septal leaflet of the tricuspid valve were supported by the medial and posterior papillary complexes respectively. Its midportion was connected to the septal group of muscles, with much variability. The posterobasal division of the septomarginal trabeculation showed considerable variability. It supported the medial papillary complex but did not form a continuous anatomical spectrum. Such arrangements of the trabeculation of the right side of the interventricular septum and the medial papillary muscle complex are directly analogous to the situations seen in hearts with deficiencies of the interventricular septum.