Sternalis
Musculus sternalis
The sternalis is an inconsistent anatomical variant present in roughly 8 percent of people, running vertically along the front of the sternum parallel to its long axis, superficial to the pectoralis major. It has no consistent training significance but is clinically notable because it can be mistaken for a mass on mammography and may complicate reconstructive chest surgery. It is included here only for completeness of regional anatomy.
- Actions
- No consistent physiological function; minor tensing of the pectoral fascia when present
- Origin
- Manubrium of the sternum or clavicle (variable)
- Insertion
- Xiphoid process, lower costal cartilages, pectoral fascia, or rectus sheath (variable)
- Innervation
- Variable: external or internal thoracic nerves (~55%), intercostal nerves (~43%), or branches of the pectoral nerves
- Blood supply
- ?