Botox in shoulder/neck muscle for relief?

Thank you for the question and photo. 
Yes, BOTOX can be used to treat any overactive muscle and I have used it to treat patients with cerebral palsy and tortcollis in the past.
However, if your trapezius (the muscle you have circled) is intentionally weakened by BOTOX then there will be some specific movements and exercises which will be more difficult to perform. You will need to discuss this in detail with your practitioner.
Unfortunately, as I am based in the UK I can't recommend a local surgeon or neurologist.
Good luck!
Dr Christopher Macdonald

Botox can be injected into any group of muscles as long as it is safe. You need to be evaluated either by a neurologist or sports medicine doctor. Good luck from New York City

Yes, the muscles you are referring to are the trapezius muscles. They are the muscles that activate shoulder shrug and other shoulder movements.These muscles can be injected to relieve tension in the muscles. You may benefit from seeing a neurologist that performs trigger point injections. Good luck!