Sternalis
Chest & Trunk
A rare chest-wall variant present in about 4% of people — can mimic a mass on mammogram or chest imaging and cause unnecessary alarm.
Function
Usually minor/uncertain; may tense chest skin/fascia
Origin
Variable: sternum, clavicle, or upper costal cartilages
Insertion
Variable: pectoral fascia, rectus sheath, ribs, or sternum
Innervation
Variable; often medial/lateral pectoral or intercostal nerves