Extensive medical literature exists which illistrates the negative effect of jaw dysfunction on
cervical musculature. One study at University of California, San Francisco, showed that anesthesizing the temporomandibular joint caused head and neck pain in various locations to resolve, even on the other side of the body.
A look at the neurology of the trigeminal nerve will likewise explain the close causal connection between jaw alignment and neck pain. The trigeminal nerve is extensively integrated with cervical nerves, both motor and sensory components.
Pain fibers from C1-C3 mix with trigeminal nerve pain fibers in the brain stem, causing pain in one to effectthe other. Typically, in TMJ Dysfunction the upper cervical is unstable leading to chronic neck pain. Biomechanically, as the mandible retrudes (typical primary pathology in TMJ Syndrome), the head comes forward causing an increase load on the neck musculature (see literature of Marian Rocabado, PT).
The trigeminal nerve has also been shown to have the ability to modulate all spinal sensory input into the brain. Hence, it can make one feel pain when there is only slight dysfunction. Through its ability to effect Substance P (neurotransmitter for pain) levels in the body, the trigeminal nerve can hypersensitize pain fibers within the neck and elsewhere.