Novel variants of the sternal muscle in an adult and an anencephalic infant: embryological insights and clinical implications
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Date
2021
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Abstract
Background: The sternal muscle is a supernumerary variant of the thoracic muscles found in 3–8% of the population. When present, it can be unilateral or bilateral, which can produce confusions during surgeries and imagenological examinations.
Methods: We report the finding of the sternalis muscle in two human cadavers, one adult and one anencephalic infant. The muscles were dissected from the fixed bodies and their morphometry analysed.
Results: In the case of the adult, we observed two sternal muscles connected in the superior portion by a central tendon. In the case of the anencephalic infant, we found a bilateral sternal muscle, in which the bellies came from the contralateral pectoralis major muscles. The two sternalis muscle variants found here were impossible to categorise according to the current classifications.
Conclusions: The sternalis muscle displays variants that are still not classified, as observed in the case of the adult and the infant, in which its presence was correlated with anencephaly. We discuss about this muscular variation in the clinical, imagenological and surgical context and propose a developmental link with the occurrence of neural tube closure defects.
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Keywords
Sternal bilateral muscle, Supernumerary muscle|Muscular variation