Brain Stem

The brain stem is located in the posterior cranial fossa and consists of medulla, pons, and midbrain. The spinal cord shows the most straightforward organization for the student, with the gray matter in the center surrounded by the white matter and there is a segmental arrangement or organization as demonstrated by the nerve rootlets from the 32 segments of the cord. The brain stem lies between the spinal cord and the diencephalon and the gray and white matters are intermixed. There are three major regions in the brain stem the medulla, pons, and midbrain, but there is no segmental organization. Each of the regions has cranial nerve rootlets Throughout the brain stem there are centers related to cranial nerves that undertake functions as diverse as breathing, swallowing, chewing, eye movements, and setting the level of consciousness. There is a major tract that originates in the motor cortex (the corticobulbar tract) that controls the motor cranial nerves.