Given the close anatomical proximity between the neck and shoulder, it’s no wonder the two are intimately related. In our hectic lifestyles of driving, hunching over computers, talking on the phone, not to mention stress arising from multiple sources, the muscles in the neck, upper back and shoulders seem to tighten up and hurt at the same time. The question is, between the neck and the shoulder, which one is the “chicken” and which is the “egg?”
The neck gives rise to the nerves that innervate the head (C1-3 nerve roots), the shoulders (C4-5), and the arms (C5-T2). Hence, there are 8 sets of nerves in the neck, 12 sets in the thoracic (middle back region), and 6 sets in the lumbar or low back region and 5 sets in the sacrum, all of which travel to a specific destination allowing us to move our muscles and to feel hot, cold, sharp, dull, vibration and position sense. When these nerves get pinched or irritated, they lose their function and the ability to feel, making it challenging to button a shirt, thread a needle, or pick up small objects. It can also make it difficult to unscrew jars, squeeze a spray bottle, or lift a milk container from the refrigerator. Hence, the nerves arising from the neck, when pinched, can have a dramatic effect on our ability to carry out our desired activities in which the shoulder, arm and hand use is required.
On the other hand, when the shoulder is injured (such as a rotator cuff tear), this can also result in neck problems. There are several ways pain from the neck affects the shoulder and vice versa. When the shoulder is injured, pain “information” is relayed to the brain starting at the nerve endings located in the area of the shoulder injury, transmitting impulses between the shoulder and the neck, and finally from the neck to the sensory cortex of the brain. That information is processed and communication to the motor cortex prompts nerve signals to be sent back to the shoulder through the neck and to the injured area (in this case, the shoulder). A reflex muscle spasm often occurs as a result, serving as kind of an “internal cast” as the muscle spasm tries to protect the injured shoulder. This can become a “vicious cycle” or never-ending “loop” until the reflex is interrupted (perhaps by a chiropractic adjustment). Another means by which both areas become injured has to do with modifications in function. We tend to change the way we go about our daily chores when an injury occurs to the shoulder, such as putting on a coat differently by leaning over to the opposite side. These functional changes can also give rise to neck pain. Because of this reflex cycle, as well as the close anatomic relationship between the neck and shoulder, not to mention the “domino effect” of soft-tissue injuries which seem to change the function at the next joint level, it’s not surprising that both the neck AND the shoulder require simultaneous treatment for optimal treatment benefit. However, the good news is, regardless which one is the “chicken or the egg,” chiropractic treatments of shoulder injuries will almost always include the neck and vice versa.