This occurs in individuals that exhibit frequent poor posture or work from a position where everything you do is in front of you like hairdressers, massage therapists, chiropractors, office and computer workers, or pretty much a good majority of people in general.
This pattern of poor body mechanics can over tighten the muscles of the chest (pecs) and traps while weakening the shoulder retractors and deep neck flexors as shown. This can be fixed by stretching the tight and overworked muscles and strengthening the weak and inhibited muscles.
Tight muscles to stretch: Pecs, Upper traps, Levator scapula, and thoracic extension.
Muscles to strengthen: Deep neck flexors and shoulder retractors
And like always, ” Be good to your body and your body will be good to you”~ Jared