Cerebellum. *THE* Cerebellum.
*not* the CEREBRUM.
The name of this structure is often confused cerebellum is the small "wrinkly" structure at the posterior (back), ventral (bottom) of the brain. Put your hand on the back of your head, move down the the ridge of bone that is the lowest part of the skull, right above the neck. Cerebellum lies directly underneath, it is protected by this bony ridge because damage to the cerebellum affects *all* of your ability to move and coordinate movement.
The cerebrum, by the way, is essentially the rest of the brain - Occipital, Parietal, Frontal and Temporal lobes - excepting the brainstem and basal nuclei of the brain.
The picture at the right shows the brainstem (the subject of the next blog) and cerebellum. H is anterior lobe of cerebellum, I is posterior lobe, and the area underneath G is the flucculonodular lobe. The latter receives conenctions from inner ear (semicircular canals - for balance) and the visual system. It is largely responsible for balance and walking movements.
The central portions of the cerebellum receive inputs from the position sensors on muscles and joints throughout the body, as well as the inner ear, then sends projections back to the spinal cord and motor cortex to control the flow of signals to the muscles. The outer or lateral parts of the cerebellum are involved in movement planning. The inputs come exclusively from the brain (and not the spinal cord or rest of the body) - in particular, the Parietal Lobe and projects back to thalamus to control movements that are about to occur.
In all, the operation of the cerebellum is not particularly well understood by persons outside a very limited field of researchers. Most of what we know comes from studies of patients with damage to the cerebellum. Cerebellar damage results in balance problems, inability to coordinate limb movements, problems with hand-eye coordination, and inability to *plan* a movement without actually *making* the movement.
Next up: Brainstem, then deep brain nuclei, then spinal cord. We're almost through with the survey of brain regions, then will go back to fill in some more specific functions of the brain, followed by brain disorders and diseases. So stay tuned for more of The Lab Rats' Guide to the Brain!