There is definitely a relationship between the neck and the shoulder, and the shoulder and the neck. They both effect each other. First of all, the shoulder is the most moveable joint in the body, therefore it is the most prone to injury of any joint in the body. The shoulder is a ball and socket joint. However, when we adjust the shoulder in addition to adjusting the gleno-humerol joint, we also adjust the sterno-clavicular, and the coracoid. The 4 muscles that hold the shoulder together are the rotator cuff muscles. These are the subscapularis, infraspinatus,supraspinatus, and the teres minor. Also, a misaligned scapula (wing bone) can also affect the shoulder on the same side. Especially if the scapula has gone lateral, which also pushes the shoulder out laterally and thus both have to be adjusted.
The nerves in the neck effect and controls the shoulders. This network of nerves is called the brachial plexus. Also, a lot of times a subluxated atlas (C-1) can affect the top of the shoulders (traps). The reason they call it the traps is because that’s where everything gets “trapped.” Sometimes people can get “tight traps.” The key muscle group between the scapula and the spine is the rhomboids. A sometimes used medical diagnosis is:”the rhomboids from hell.”