The rectus sternalis muscle is an anatomical variation that lies in front of the sternal end of the pectoralis major parallel to the margin of the sternum.

The sternalis muscle often originates from the upper part of the sternum and can display varying insertions such as the pectoral fascia, lower ribs, costal cartilages, rectus sheath, aponeurosis of the abdominal external oblique muscle.

[13] It may also take part in the movement of the shoulder joint or have an additional role in elevation of the chest wall.

[17] However, there is a potential benefit of the muscle as it can be used as a flap in a reconstructive surgery of the head and neck and the anterior chest wall.

[18] Different terminologies have been given to the sternalis due to its highly varied morphology and the disagreement on its embryonic origin.