Home    | About Us    | News & Events    | Academic Affiliates    | Contact Us    | Directions

Health Information Services Physicians Referring Physicians Hospitals and Clinics MyHealth Patients & Visitors Faculty & Staff

Neuromedicine Neurological Surgery Chiari I Malformation About Chiari Malformation Anatomy of the Brain Diagnosis Neurological Exam Questions to Ask Recovery Symptoms Treatment

Anatomy of the Brain

The brain is enclosed in the skull, a rigid bone, and divided into two main sections, or hemispheres. Within the hemispheres are four fluid-filled cavities called ventricles. The ventricles are pockets filled with cerebrospinal fluid (CSF), which flows around the brain and spinal cord. CSF is a clear, water-like substance produced in the lateral ventricles. Total CSF volume is approximately 150 milliliters, or about one pint. In an adult, it is normally absorbed and reproduced about four times per day. CSF normally flows through the ventricles, down through the posterior fossa and into the spinal canal. The function of the cerebrospinal fluid is to bathe and nourish the brain and spinal cord.

The lower-most part of the brain is the cerebellum and brain stem, which are located in an area called the posterior fossa. This area is just at the base of the skull, which attaches to the spinal cord. Within the posterior fossa lie the brain stem and cerebellum. The fourth ventricle also is located within the posterior fossa. The cerebellum is the lowest part of the brain. The cerebellum is made up of three major lobes, which are composed of nerve fibers connected to the spinal cord. Two small portions of cerebellar tissue, called the cerebellar tonsils, normally lie within the posterior fossa. These tonsils are different from those in the throat. Scientists believe the cerebellum is the part of the brain that controls coordination and fluidity of movements. Disorders of the cerebellum can include unsteady gait, balance problems and difficulty with fine-motor tasks.