Incidence of sternalis muscle in the caldas population (Colombia): Anatomical variations

Abstract

The musculus sternalis is an anatomical variant that occurs in 3-8% of the world population and its incidence is higher in women. It can be found unilaterally or bilaterally and is located in the anterior wall of the thorax, where its fibers run parallel to the sternum and superficial to the medial part of the pectoralis major muscle. The main objective of this study was to quantify the incidence of musculus sternalis in the population of Caldas (Colombia) and, therefore, 68 cadavers of adult individuals were used during a period of twenty years to determine the incidence of this muscle and describe its anatomical characteristics. Two cadavers had this muscle, which was equivalent to 2.94% of the sample, where one was located unilaterally and in other bilaterally. In the case of unilateral presence, the muscle presented an oblique direction thatdoes not coincide with any subtype of the classification given for these muscles. In bilateral presentation, both muscles were continuous at their upper ends with the respective sternocleidomastoid muscle. In addition, the right musculus sternalis had a digastric shape, which also does not coincide with any subtype of the classification.