Seven-Headed Sternalis: A Case Report with Three-Dimensional Presentation Using Photogrammetry.

Area of Science:

• Anatomy
• Medical Imaging

Background:

• The sternalis muscle is a known anatomical variation of the chest muscles.
• Its descriptions and classifications vary widely in scientific literature.
• It remains unfamiliar to many clinicians and radiologists.

Purpose of the Study:

• To present a novel variant of the sternalis muscle with seven distinct muscle bellies.
• To document the unique morphological characteristics of this variation.
• To highlight the clinical relevance of such anatomical variations, particularly for breast surgery.

Main Methods:

• Anatomical dissection of a 79-year-old male donor.
• Detailed description of the sternalis muscle variant's morphology, including origin, number of heads, and dimensions.
• Three-dimensional imaging using photogrammetry to visualize the variation.
• Identification of the innervation source for the inferior heads.

Main Results:

• A sternalis muscle variant composed of seven muscle bellies was discovered.
• Two superior heads originated from bilateral accessory heads of the sternocleidomastoid muscles.
• Five additional heads arose from the pectoralis major fascia (three left, two right).
• The left and right portions measured 6.6 cm and 5.3 cm in width, respectively.
• Intercostal nerves innervated the inferior heads.

Conclusions:

• This seven-headed sternalis muscle configuration represents an exceptionally rare and previously unreported anatomical variation.
• The detailed documentation and 3D imaging provide valuable anatomical data.
• Understanding such variations is crucial for accurate diagnosis and surgical planning, especially in breast procedures.