MS-4125

MS-4125

A 15-year-old boy comes to see his GP accompanied by his mother who is worried about his facial expressions. The boy has been experiencing difficulty using the muscles in his face for the past month. He also reports weakness in his arms, but no pain.

During the examination, the GP observes that the boy’s facial muscles are weak, he struggles to puff out his cheeks, and has difficulty raising his arms in the classroom. Additionally, the boy has abnormally large gastrocnemius muscles and his scapulae are ‘winged’.

Which nerve is responsible for innervating the muscle that prevents the scapulae from forming a ‘winged’ position?