Shots are given in specific places of the body determined by the place where the vaccine is best absorbed into the vessels. In the case of a tetanus shot, the best place to put it is inside a muscle. The arm contains enough muscle near the shoulder that a shot can be safely placed there without too much fear of damaging any other structures with the vaccine needle. Most shots can be given in more than one place. For example, the gluteal muscle (in the behind) is another good place to put a shot. Perhaps you can ask your nurse to place the shot there. Keep in mind that a tetanus shot will make you sore no matter where it gets placed. So expect to have an aching pain where ever it goes.
Either way, you should get the tetanus shot if it has been more than 5 years since your last one. Rusty nails are a great place to catch tetanus, which can be deadly unless you are immune.
I suggest that you schedule an appointment with your primary care physician
. After examining the wound, your doctor
will likely want to give you the tetanus shot. I think your he or she will oblige your request to have the shot placed somewhere other than your arm.