Unusual innervation pattern of pectoralis minor muscle-anatomical description and clinical implications

The highlight of the current case study is unique branching pattern of the medial pectoral nerve in relation to the pectoralis minor muscle. In addition, the third thoracic spinal nerve also was observed to penetrate the muscle. The lateral pectoral nerve did not innervate the muscle. The pectoralis minor was observed to be pierced extensively by multiple branches from medial pectoral nerve. Therefore, this study was planned to report this unusual presentation. Such an extensive neural arrangement in relation to pectoralis minor is rather unusual and to the best of our knowledge has been not reported earlier. The possible clinical consequence of much an anomaly could be motor and sensory loss associated with accidental injury of these multiple nerves penetrating the substance of pectoralis minor while performing axillary lymphadenectomy. In accordance to the above case description, the surgeon should be cautioned of these possible neural branches while performing axillary dissection in mastectomy. Additionally, iatrogenic sensory or motor losses may be prevented by appropriate knowledge of these variations.