The "Serratus Punch"

Disorders of the shoulder and neck seem to be linked to problems with the serratus anterior (SA) muscle. Exercises for that muscle may help in rehabilitation; the question is what movement optimally targets the serratus anterior, and what exercise does so while minimally involving other muscles, such as the pectoralis major (PM), that synergize with the serratus anterior in its function. A study has been performed, conclusion from the abstract:

CONCLUSIONS: All exercises activated the PM between 15 and 29% Maximum Voluntary Isometric Contraction and the SA between 15 and 43%. The Modified Push-Up Plus exercise against the wall and the floor activated the SA and PM to a similar degree. When maximum activation of the SA with minimal activation of the PM is desired in healthy subjects, the "Serratus punch" seems to be the optimal exercise.

The "Serratus punch" exercise is shown in this YouTube video. As always, consult your physician before doing any rehabilitation. Do not self-diagnose and start doing such activities without knowing whether it is appropriate for you; you may make your specific condition worse.