A Possible Accessory Muscle of the Serratus Posterior Superior Muscle

Abstract

Anatomical variation is defined as the normal range of possibilities in the topography and morphology of body structures. In contrast, an anomaly is any structural or functional anatomical finding beyond the normal range of possibilities. This case study describes a muscular anomaly found in a 73-year-old preserved Caucasian male. We observed a left-sided anomalous muscle originating from the transverse process of the C1 (Atlas) vertebra and inserting onto the proximal attachment of the serratus posterior superior (SPS) muscle at the C7 level. We suggest that this anomaly is a result of early embryological development and hypothesize that the atypical neck muscle may reinforce the action of the SPS. This finding is rare and no reference of it can be found in the literature. Reporting anatomical anomalies is important for the medical literature and education.