A Bilateral Double Sternalis Muscle in a Korean Cadaver / 체질인류학회지

Although the sternalis muscle has been well known to anatomists, it is quite unfamiliar to clinicians. During routine educational dissection, we came across a well-defined bilateral double sternalis muscle innervated by the intercostal nerve, respectively. The right sternalis muscle 1) became tendinous to insert into the sternum and 2) crossed midline and then intermingled with the left pectoralis major muscle, which could be classified into a double with single cross based on Snosek et al.'s criteria. The left sternalis muscle was composed of two bellies, which were combined at the midway, and became tendinous to insert into the contralateral manubrium, which could be classified into a bicipital diverging with double cross based on Snosek et al.'s criteria. The detailed knowledge on the sternalisis is important for clinicians as well as for anatomists, since the clinical importance of the sternalis muscle has been highlighted in recent years.

Sternalis muscle: an anatomic variation of the anterior chest wall

The sternalis muscle’s presence is an uncommon anatomic variation of the anterior chest wall’s musculature. It is insufficiently mentioned by the most of anatomical textbooks, although it has been well described by the literature. The study of this anatomic variation is extremely relevant, principally for the interpretation of image’s exams that approach this region. For this study’s achievement, 102 cadavers were dissected (97 of the male sex and 5 of the female sex). The study of the sternalis muscle avoids the expenses with exams and the indication of aggressive treatments in a wrong way.

Sternalis muscle: Anatomical variations in Thais.

Objective: To study and classify the types of the sternalis muscle in Thais, who has lived in Bangkok and the surrounding area, and compare its incidence to that of the other races. Methods: The sternalis muscles were dissected and classified in Thai cadavers. The morphology of each type was shown by photograph. Tables showed numbers and percentage of the muscle in male and female, right and left sides. Results: The study of 126 Thai cadavers, the sternalis muscle was found in 9 cadavers. The incidence was 7.14%. The muscle was divided into 2 types, type A was the bilateral type and type B was the unilateral type. Conclusion: The sternalis muscle was an anatomical variation of the thoracic wall musculature. Its incidence in Thais was 7.14%. The morphology of the muscle was shown and divided into 2 types.

Sternalis Muscle Encountered during Immediate Breast Reconstruction: 2 Case Reports

The sternalis muscle is an uncommon variation in the anterior chest wall which is located superficial to the pectoralis major, coursing vertically almost parallel to the sternum. It exists unilaterally or bilaterally, as thin muscle strips or a broad band of muscles. We report two cases of skin sparing mastectomy and immediate breast reconstruction in which the sternalis muscle was encountered. This unusual variation might puzzle radiologists to mistake it for a tumor or an abnormal bulging of the pectoralis. Surgeons also must not be surprised to encounter this muscle during surgery of the breast or pectoralis and keep the appropriate dissection plane.

Implication of Sternalis Muscle on Staged Breast Reconstruction with Implant

PURPOSE: The sternalis muscle is an accessory muscle of the anterior chest wall. This is a rare anatomic variant reported in approximately 8 percent of the population, with variation among races. While several anatomic studies of the sternalis muscle exist, nothing in the literature addresses the implications of this muscle on staged breast reconstruction with implant. METHODS: We encountered two consecutive patients with a left sternalis muscle who underwent immediate staged breast reconstruction with a tissue expander. We offer a strategy for dealing with this rare, but known, anatomic variant during staged implant reconstruction. Firstly, recognizing the presence of a sternalis muscle mandates the elevation of the pectoralis major muscle and the sternalis muscle in continuity. Secondly, slight modifications must be made during the submuscular dissection to create a properly placed pocket for the tissue expander. RESULTS: While our encounters with this anatomic variant are few, our experiences with two consecutive patients illustrate that the reconstructive surgeon must be familiar with the sternalis muscle and be prepared to adapt his or her technique for tissue expander placement when faced with this accessory muscle. CONCLUSION: To date, no reports exist in the literature describing the operative implications of this anatomic variant. We offer our technique for dealing with this accessory muscle during staged implant reconstruction of the breast.