Sternalis or rectus? An analysis of terminological usage based on case reports of the sternalis muscle

The sternalis muscle is a relatively rare anatomical variant that lies superficial to the pectoralis major muscle. In English-language literature, it is commonly referred as "sternalis muscle" or "rectus sternalis." Although the second edition of the Terminologia Anatomica (TA) officially designates "sternalis muscle" as the standard term, terminological inconsistencies persist. This study investigated the actual usage of these terms based on a literature review of previously published case reports. We analyzed 77 articles comprising 92 cases, retrieved through PubMed and Google Scholar, examining the types of terms employed, their frequency, regional distribution, and temporal trends. As per the first and second editions of TA, the terms were categorized into two groups: the S group ("sternalis muscle" or "sternalis") and the R group ("rectus sternalis" or "rectus sternalis muscle"). Our analysis showed that unilateral cases and male patients were more frequently reported. Regionally, the highest number of reports originated from Asia. The frequency of S group usage exceeded that of R group usage by scale factors of 1.6, 2.3, and 3.8 in Asia, Europe and the Middle East, and North America, respectively. Furthermore, S group term usage increased after the release of the first edition of TA (TA1) and stabilized following the release of the second edition (TA2). These findings suggest that the TA-compliant term "sternalis muscle" has become dominant in English-language literature, supporting standardized anatomical nomenclature and facilitating consistent communication among anatomists and clinicians. This framework may also serve as a model for standardizing terminology related to other anatomical variants.