Sternalis and axillary arch muscles as rare anatomical variations with surgical significance in breast and axillary surgery

Abstract Vestigial muscles like the sternalis and axillary arch muscles are rare anatomical variations with important surgical implications. Though often asymptomatic, they can impact imaging interpretation and surgical approaches. This study presents a case of a 37-year-old woman undergoing a modified radical mastectomy, where both muscles were incidentally identified. The sternalis muscle, a rare thoracic wall anomaly, can be mistaken for a pathological lesion, while the axillary arch muscle may interfere with axillary surgeries. Recognizing these variations is crucial to avoid misdiagnosis and intraoperative complications, ensuring optimal patient outcomes.