The brain stem consists of three main areas, the Midbrain, the Pons and the Medulla Oblongata. They are responsible for sustaining the basic functions of life.
The Midbrain is the top most structure of the brain stem. It contains major relay stations for neurons which transmits signals to the cerebral cortex. Reflex centers are the pathways that carry sensory (input) information and motor (output) commands. Relay and reflex centers for visual and auditory (hearing) centers are located in the top portion of the midbrain. At the bottom of the midbrain are reflex and relay centers relating to pain, temperature and touch. In addition, there are several areas that are associated with the control of movement.
There are two pairs of nuclei called Superior Colliculis and Inferior Colliculis. The Superior Colliculis control reflex actions of the eyes. These include movements such as blinking, opening and closing of the pupil and focusing the lens. The second pair of nuclei, the Inferior Colliculis controls the auditory reflexes, such as the adjusting the ear to the volume of sound.
The Pons is mainly a relay center that links the cerebral cortex with the medulla oblongata. There are large bundles of nerves that connect the two halves of the cerebellum as well as the opposite side cerebral hemisphere.
The Medulla Oblongata is the stalk like portion of the brain stem. The Midbrain and the Pons sit atop of the Medulla Oblongata. The medulla oblongata makes a gradual transition into the spinal cord at he foramen magnum. The reticular formation runs up and through the pons and midbrain. It controls respiration, cardiovascular function, digestion, levels of alertness and patterns of sleep. It is responsible for determining which parts of the constant flow of sensory information into the body are received by the cerebrum.
Sensory and motor nerve fibers connecting the brain and the rest of the body cross over to the opposite as they pass through the medulla oblongata. The left side of our brain communicates with the right side of the body. The right side of the brain communicates with the left side of the body.
There are 12 pairs of cranial nerves that arise symmetrically from the base of the brain. They are numbered front to back in the order in which they rise. They connect mainly with structures of the head and neck such as the eyes, ears, nose, mouth, tongue and the throat. Some are motor nerves that control muscles. Some are sensory nerves conveying information from sense organs. The first and second pairs of cranial nerves, the olfactory (smell) nerves and the optic nerves (vision) carry sensory information. The remaining ten pairs of cranial nerves originate in or end in the brain stem.
Thalamus and the Hypothalamus
They both lie underneath the cerebrum and connect it to the brain stem. The Thalamus is the main relay station for incoming sensory signals to the cerebral cortex and for the outgoing motor signals from it. All sensory input to the brain, except for the sense of smell connects to individual nuclei of the thalamus. The Hypothalamus regulates or is involved directly in the control of many of the body's vital drives such as eating, drinking, temperature regulation, sleep, emotional behavior and sexual activity.
Our symptoms range from vision disturbances to bodily temperature changes to numbness and burning sensations. By understanding what functions take place in the brain stem will lead to a better understanding of why these symptoms are symptoms. We don't have to be ignorant about the anatomy of our bodies. The more we know the better we can take care of ourselves and our children. If I can see that Chiari causes these symptoms by compressing the brain stem...why can't the doctors? Why do they dismiss our symptoms as not being related? Keep searching for answers....and never give up the fight. The future of these diseases and how they are being treated is going to be changed by us.
Connie
