Hello and welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. As muscultaneous nerve is one of the major nerve which supplies to many muscles of your upper arm directly and its branches supply to muscles of forearm and hand, so if it has been damaged you are bound to have weakness in majority of your arm muscles. So what best you can do is visit a physiotherapy clinic and meet the physiotherapist where a machine called as muscle stimulator can help you in many ways (like preventing muscle wasting and regaining strength back). It will be a very slow process and it might take you own time, like two months to get a noticeable difference in your arm. But along with exercises and if you continue to extend the treatment we can expect good results in a span of six months to one year or sooner. It depends how you respond to the treatment Kindly have your NCV done of radial nerve, ulnar nerve and median nerve of your hand. Hope to hear from you soon once you had taken sessions. There are other things also which might help you we will discuss about them later. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Harsh Swarup