Sometimes there are two “separate structures” that function interdependently. The neck and shoulder are a perfect example of this. Whether you are looking at musculature, neurological structures, or other factors such as lymphatic drainage or even parasympathetic innervation, the neck and shoulders generally look similar or at least share much of the same anatomical space. The brachial plexus originates from the spinal cord in the neck and then exits through the armpit befo