RESUMO
INTRODUCTION: On the anterior thoracic wall, some supernumerary muscular masses can be present, like the sternalis muscle, which is situated over the pectoralis major muscle fascia, deep to the subcutaneous tissue. Its fibers can be parallel or oblique to the sternum, and are clinically important due to the possibility that during certain radiologic procedures they can be confused with some types of breast pathologies. MATERIAL AND METHODS: Bibliographic review of supernumerary muscular masses of the anterior thoracic wall and case report in a colombian male cadaver of mixed ethnia, dissected by medical students at the Department of Morphology at the Universidad del Valle, in Cali, Colombia. RESULTS: In the right side of the anterior thoracic wall of the cadaver an anatomical variation of low occurrence in the general population, the sternalis muscle, was found. The muscle fibers had a vertical direction, parallel to the right sternal margin. Considering all the muscular fascicles, its dimensions were approximately 7,0 cms in length and 2,9cms in width. CONCLUSION: Having in mind the characteristics of the present anatomical variation, and that there can be some radiologic, surgical and clinical implications, it is important for the health professional to know the anatomy and epidemiology of the sternalis muscle.
