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Revisiting the right atrial pectinate muscles: Anatomical variability and a simplified morphological classification
S Madani1, V Defaweux2, A Lagier2
1Department of Cardiovascular and Thoracic Surgery, University of Liège, Liège, Belgium.
Morphologie : Bulletin De L'Association Des Anatomistes
|June 25, 2026
Summary
The pectinate muscles (PM) and crista terminalis (CT) in the right atrium exhibit significant anatomical variability. A new three-type classification simplifies their description and aids in clinical applications.
Area of Science:
- Cardiovascular Anatomy
- Cardiac Surgery
Background:
- The pectinate muscles (PM) and crista terminalis (CT) are key anatomical structures within the right atrium.
- Understanding their morphological variability is crucial for cardiac procedures.
Purpose of the Study:
- To detail the morphological variability of the right atrial PM and CT.
- To assess the presence of the taenia sagittalis (TS).
- To introduce a simplified anatomical classification system.
Main Methods:
- Dissection of 45 adult human hearts.
- Standardized protocol to expose CT and PM.
- High-resolution photography and independent analysis by two cardiac surgeons.
Main Results:
- The CT was consistently identified.
- Three PM organizational patterns were observed: Type I (33.3%), Type II (46.7%), and Type III (20.0%).
- A single TS was the most common finding.
Conclusions:
- Right atrial PM display considerable anatomical diversity.
- A proposed three-type classification offers a simplified, reproducible framework.
- This classification may enhance imaging, electrophysiology, and surgical interventions, and inform studies on atrial arrhythmogenesis.
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