From the NUCCA website: NUCCA (National Upper Cervical Chiropractic Association) is a gentle, non-invasive technique was developed more than forty years ago to create a radical new way of healing that can help restore body balance and perfect health. The focus of the NUCCA work is the relationship between the upper cervical spine (neck) and its influence on the central nervous system and brain stem function. It is this relationship that affects every aspect of human function from the feeling sensations in your fingers to regulating hormones, controlling movement, and providing the ability to hear, see, think, and breathe (and eat!).
Because a person suffering from Chiari already has a "crowded" brainstem, this technique is helpful in opening up that area to allow for normal flow of cerebral spinal fluid and blood, and normal functioning of the nervous system.
The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves. Though small, this is an extremely important part of the brain as the nerve connections of the motor and sensory systems from the main part of the brain to the rest of the body pass through the brain stem. This includes the corticospinal tract (motor), the posterior column-medial lemniscus pathway (fine touch, vibration sensation and proprioception) and the spinothalamic tract (pain, temperature, itch and crude touch). The brain stem also plays an important role in the regulation of cardiac and respiratory function. It also regulates the central nervous system, and is pivotal in maintaining consciousness and regulating the sleep cycle. The brain stem has many basic functions including heart rate, breathing, sleeping and eating.