A 54-year-old woman presents to her primary care physician after noticing a firm lump in her right breast. She undergoes fine needle aspiration of the mass, which reveals a grade 3 invasive ductal carcinoma with overexpression of the HER2/Neu oncogene. Following surgical resection of the mass and axillary lymph node dissection, the patient undergoes breast reconstructive surgery. Two weeks after her surgery, she starts noticing a bony protrusion in her back everytime she lifts her right arm. Which of the following is the most likely origin of the injured nerve in this patient?
- Inferior trunk of the brachial plexus
- Posterior cord of the brachial plexus
The patient in this vignette has suffered damage to the long thoracic nerve as a result of radical mastectomy. The long thoracic nerve arises from the nerve roots of C5-C7 to innervate the serratus anterior muscle. The serratus anterior normally serves to abduct the arm beyond 90 degrees to the body. Lesion of this nerve can lead to “winging” of the scapula.