The human heart's efficient function relies on the coordinated action of its structural components, among which the papillary muscles play a pivotal role. These muscles, located within the ventricles, anchor the chordae tendineae, which in turn attach to the atrioventricular valves, preventing their prolapse during systole. ^[1] Traditionally, the right ventricle is described as having three papillary muscles—anterior, posterior, and septal—while the left ventricle contains two—anterolateral and posteromedial. ^[2]

However, anatomical studies have revealed considerable variability in the number, morphology, and arrangement of these muscles. Such variations can influence the hemodynamics of the heart and have clinical implications, especially in surgical interventions like valve repair or replacement. ^[3] For instance, an accessory papillary muscle might be mistaken for a pathological mass during imaging or surgery, leading to misdiagnosis or inadvertent injury. ^[4]

Previous research has documented these variations. In a study analyzing 100 adult human hearts, the right ventricle exhibited the typical three papillary muscles in 84% of cases, while 16% had only two groups, indicating rudimentary or absent septal papillary muscles. ^[5] The left ventricle showed two papillary muscles in 73% of hearts, with additional groups observed in the remaining specimens. ^[6]

Understanding these variations is crucial not only for anatomists and pathologists but also for clinicians and surgeons. Accurate knowledge can aid in the interpretation of imaging studies, guide surgical approaches, and prevent potential complications arising from unrecognized anatomical anomalies. ^[7]

This study aims to provide a comprehensive analysis of the variations in the number and morphology of papillary muscles in adult human hearts, thereby contributing valuable information to the existing body of anatomical and clinical knowledge.

The study was performed on 25 formalin preserved hearts procured from cadavers of GMC Nizamabad. The number of papillary muscles in each ventricle was noted along with its pattern. The results were compared to results of previous study by a tabular form.

Inclusion Criteria

• Adult human hearts aged between 17 and 80 years.
• Hearts without any gross pathological lesions or congenital anomalies.
• Specimens with intact ventricular structures suitable for dissection.

Exclusion Criteria

• Hearts with evident pathological conditions affecting the myocardium or valves.
• Specimens with prior surgical interventions or trauma affecting the heart.
• Decomposed or damaged specimens unsuitable for detailed anatomical study.

 Dissection Procedure

Standard autopsy techniques were employed for the dissection. Each heart was opened along the appropriate anatomical planes to expose the ventricular cavities. The right and left ventricles were examined separately. The number, position, and morphology of papillary muscles were documented. Particular attention was paid to the number of muscle bellies, their arrangement, and any accessory muscles present.

Data Collection and Analysis

Data were recorded systematically, noting the number of papillary muscles in each ventricle, the number of bellies in each muscle, and their spatial arrangement. Photographic documentation was undertaken for representative specimens. The data were analyzed to determine the frequency and patterns of variations.

A total of 25 adult human cadaveric hearts were studied. Both right and left ventricles were examined for the number of papillary muscles, number of bellies, morphological variations, and presence of accessory muscles.

Table 1: Number of Papillary Muscles in the Right Ventricle

Table 2: Number of Papillary Muscles in the Left Ventricle

Table 3: Number of Bellies in Anterior Papillary Muscle (Right Ventricle)

Table 4: Number of Bellies in Posterior Papillary Muscle (Right Ventricle)

Table 5: Morphological Variations of Papillary Muscles

Table 6: Presence of Accessory Papillary Muscles

This anatomical study, conducted on 25 adult cadaveric human hearts, revealed notable variations in the number and morphology of papillary muscles in both ventricles, emphasizing the need for a nuanced understanding of cardiac architecture in clinical practice.

In the right ventricle, the classical description of three papillary muscles—anterior, posterior, and septal—was observed in 80% of specimens. However, 20% showed only two identifiable muscles, lacking a distinct septal group. Such findings align with reports by Ghosh et al. and Standring et al., who noted that the septal muscle can be rudimentary or poorly developed in some individuals. ^[8] The absence of a septal papillary muscle may affect the mechanics of the tricuspid valve, potentially predisposing to leaflet malcoaptation or regurgitation in certain conditions. ^[9]

In the left ventricle, 72% of specimens conformed to the standard anatomy with two papillary muscles—anterolateral and posteromedial. However, 28% showed additional groups or subdivisions, corroborating earlier observations by Loukas et al. and Sareen et al. who emphasized the clinical relevance of accessory papillary muscles. ^[10] These muscles could mimic intracardiac masses in imaging modalities such as echocardiography or MRI, necessitating careful interpretation to avoid false-positive diagnoses of tumors or thrombi. ^[11]

The number of bellies in each papillary muscle also showed variation. The anterior papillary muscle of the right ventricle had a single belly in 60%, but some showed two or three, reflecting developmental variability. A similar pattern was observed in the posterior group. Increased muscle bellies may alter the tension dynamics on chordae tendineae, which could impact valve function or lead to uneven stress distribution. ^[12]

Morphologically, conical papillary muscles were the most common, observed in 72% of total muscles examined. Bifurcated and flat-topped muscles, though less common, were present and carry clinical implications. ^[13] For instance, bifurcation may represent incomplete separation during embryological development or hypertrophy due to increased load. ^[14]

Accessory papillary muscles, defined as additional muscle groups with no consistent position or chordal attachment, were found in 16% of right and 24% of left ventricles. Their significance is underscored during valve surgeries, particularly in mitral valve repair, where inadvertent excision may result in valvular incompetence or mechanical complications. ^[15,16]

Overall, this study reiterates the anatomical variability of papillary muscles and their clinical implications in imaging, surgery, and understanding congenital or acquired valvular dysfunctions. Though the sample size was limited to 25, the findings are consistent with larger studies and emphasize the importance of individual anatomical assessment in cardiac practice. Further studies with larger cohorts and imaging correlation (e.g., 3D echocardiography) are recommended to expand on these findings and translate them into surgical planning and diagnostic accuracy.

The study underscores the considerable variability in the number and morphology of papillary muscles in the human heart. Recognizing these variations is essential for accurate anatomical understanding, effective surgical planning, and avoiding potential clinical complications. Further research with larger sample sizes and advanced imaging techniques could provide more insights into the functional implications of these anatomical differences.

We observed the normal anatomy of papillary muscles in left ventricle and following variations in right ventricle

1. Two posterior Papillary muscles

2. Numerous Posterior Papillary muscles

3. Two fused posterior paillary muscles
4. Two Posterior Papillary muscles [1+3 fused]

5. Two Anterior Papillary muscles [2 fused]

6. 2 Posterior Papillary muscles

7. Fused 2 anterior papillary muscles

8. Fused two posterior papillary muscles

9. Sub Endocardial course of septal Papillary muscle and trabeculae

ANTERIOR PAPILLARY MUSCLE

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