The brainstem is a vital part of the central nervous system; it is responsible for regulating many of the functions and actions of the body that are not under conscious control, so called autonomic functions. This includes heart rate, blood pressure, breathing rate, digestion and sleep. Dysfunction of the brainstem can cause a multitude of different symptoms and plays a role in many different conditions.
The brainstem comprises three different parts; the Midbrain, Medulla Oblongata, and the Pons. Each of these parts plays a role in the regulation of different parts of the nervous system. The brainstem is also the source of a collection of nerves called the Cranial Nerves, these nerves supply structures within the head, neck, and face. The Cranial Nerves innervate the eyes, ears, nose, mouth and throat, facial muscles, sensation in the face. When these nerves become dysfunctional we see a lot of different symptoms occur, including tinnitus, dizziness, facial palsy, facial pain.
Location of The Brainstem..
The brainstem sits under the cerebral hemispheres and in front of the cerebellum, it protrudes downwards towards the base of the skull and exits the skull via the foramen magnum. As it exits the skull it becomes continuous with the spinal cord and is protected by the bones of the spine (vertebrae), the first of which are the bones of the upper cervical spine (C1 and C2). The lower brainstem and the spinal cord are attached to the inside of the vertebra by strong ligaments called the dentate ligaments. These aid in keeping the spinal cord suspended within the neural canal and allows it to move with the motion of the vertebrae. Peripheral nerves exit the spinal cord via spaces between the vertebrae carrying information to and from the brain keeping every cell in your body functioning correctly in a coordinated manner.
When the bones of the upper cervical spine are misaligned, brainstem function can be impacted through different mechanisms. Firstly the mechanical stress placed upon the lower brainstem and spinal cord due to the dentate ligament attachments can cause torsion to these neural structures which will negatively impact the way they function. Secondly, the blood supply to the CNS can be impacted.
This can be at the level of the small blood vessels directly supplying the spinal cord, due to the mechanical stress of the misalignment these small vessels may not be able to supply the spinal cord as efficiently. Thirdly the vertebral arteries, carotid arteries, and internal jugular veins can be affected by upper cervical misalignment. This is due to their proximity to the top bones in the neck, when these are out of their normal position it can disrupt normal blood flow causing slight pooling of the blood as it enters or exits the cranium. This can be a contributing factor in headache disorders. Lastly, cerebral spinal fluid flow can be interrupted. The CSF bathes the CNS and keeps it buoyant within the skull, it also helps transport nutrients to the CNS and remove waste products. When the CSF doesn’t circulate correctly it can pool within the cranium and impacts brain function, this is common in people who suffer with brainfog and other cognitive disorders.
Assessing the function of the brainstem is a key part of our assessment of patients and is monitored throughout care using a variety of testing throughout care. As brainstem function and nervous system adaptability improves health will follow!
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