Introduction

The sternalis is a normal anatomical variant that is typically poorly understood and not taught at undergraduate level. It is a thin, para‐sternal strap muscle that originates from the upper sternum and infra‐clavicular region with variable insertion points from the pectoral fascia to the rectus sheath. Its innervation and function are also relatively uncertain. The muscle can be found unilaterally (4.5% of cases) or bilaterally (1.7% of cases). Great variation exists in the reported incidence rates between the sexes and also among the different ethnic groups.

Methods

During the preparation for undergraduate anatomy teaching, 18 cadavers were prepared for dissection with removal of the skin and superficial tissue of the chest wall. A review of the existing literature was then carried out to understand the incidence of the sternalis.

Results

Of the 18 cadavers, three were found to have this anatomical variation of the anterior chest wall, giving an incidence rate of 16.7%. The small sample size of this study is a noted limitation but the findings do suggest further evaluation would be provident.

Conclusion

The incidence of 16% in our small cohort suggests that sternalis may be more common than previously thought and should be included in more regular undergraduate teaching. The sternalis has significant clinical applications in both radiology and reconstructive surgery – its presence is potentially misdiagnosed as benign or malignant breast lesions during screening. Additionally, the muscle can potentially be used in head and neck, chest wall or breast reconstructive surgeries.

The findings from this cadaveric study also suggest that compiling a database to record the occurrence of sternalis muscles would be beneficial in producing more accurate epidemiological data.

No ethical approval was required for this study.