Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 8 2 2023 11 18 88 90 Ziba Khanmoradi Department of Neurology, Kermanshah University of Medical sciences, Kermanshah, Iran. Kian Zohrabi Department of Orthopedic Surgery, Kermanshah University of Medical sciences, Kermanshah, Iran. Zohreh Abna MS Fellowship, Department of Neurology, Tehran University of Medical Sciences, Tehran, Iran. 2023 06 29 2023 08 19 The accessory nerve is the eleventh cranial nerve that supplies the sternocleidomastoid and trapezius muscles. Injury to the spinal accessory nerve is most commonly caused by medical procedures that involve the head and neck, which causes wasting of the shoulder muscles, winging of the scapula, and weakness of shoulder abduction and external rotation. Here, two cases of spinal accessory neuropathy after injection of trapezius muscle for body building are reported. https://crcp.tums.ac.ir/index.php/crcp/article/view/840