You have to approach all parts, spasms and or trigger points in the muscles as well as any stuck or raised top rib..
Just focusing on 1 part will not do much in the long term..

Other areas to look at -
pec minor
lymph drainage
overall body postures & uses..
past whiplash or old injuries
sleeping postures- pillows/mattresses
ergonomics

site search can find those topics for more on them..and more in the sticky threads..
https://www.neurotalk.org/search.php