The coronoid insertion of the human masseter muscle was well described in the 18th century

A recent paper in Annals of Anatomy (The human masseter muscle revisited: First description of its coronoid part) claimed to have discovered a previously unrecognized anatomical component of the deep layer of the masseter muscle. The goal of this study is to emphasize the importance of undertaking comprehensive exploration of the historical literature before asserting primacy of an anatomical discovery.

A search was conducted of historical texts describing the anatomical structure of the masseter muscle, spanning the 18th, 19th, and early 20th centuries. Historical sources were obtained via Google Books, the Internet Archive, and the digital collections of Stanford Lane Library Medical History Center, Paris University Numerical library Medica (France), and the State Library of Bavaria (Germany). Contemporary anatomical studies were identified via PUBMED search RESULTS: Rather than a "first description" of newly discovered anatomical feature, the paper we comment upon has added important anatomical details of the length, width, thickness, and fiber orientation of coronoid portion of the deep layer of the masseter. As early as the 18th century, anatomists had described the masseter as possessing a three rather than two-layer structure with a deep layer which inserts on the coronoid process.

Assertions of primacy (ie. "first description") of an anatomical structure in the 21st century necessitates a diligent search of literature, including sources which were published during the era when anatomical studies reigned supreme at the forefront of medical science. Systematic scanning of historical medical material has made older texts widely and freely available and digital translation tools have helped to remove language barriers. It is important to study original articles as secondary citations of historical material are less reliable. Without rigorous historical investigation, assertions of primacy cannot be made with confidence.