Fine motor control and learning, spatial sense, balance, proprioception, cognition The metencephalon contains the pons and cerebellum—structures involved in motor function. Cranial motor neurons synapse in the pons and the cerebellum. The cerebellum supports fine-tuned motor movements. The cerebellum, squeezed beneath the occipital lobe—looking like a miniature brain (“cerebellum” means “little brain”), with hemispheres—is not cross-wired as its big brother is. It is neurally dense, making up only 10% of the brain’s size, yet it contains most of its neurons. It is richly interconnected and multifunctional, straddling domains of action, perception, and thought. The pons (meaning “bridge”) is not only a sensory relay structure, connecting the cerebral cortex to the cerebellum, spinal cord, medulla, and thalamus; it also allows for breathing without conscious attention (aided by the medulla). The pons also supports rapid eye movement (REM) sleep.
Alcohol intoxication With enough alcohol, you might have experienced cerebellar malfunction. Staggering, a broad-legged walk, inability to walk straight, and clumsiness result from intoxicated cerebellar neurons.
Coma As discussed in the section “Mesencephalon (Midbrain)”, insult to the reticular formation (a structure found in the metencephalon as well) often results in a coma. Intoxication is the most common cause.
Locked-in syndrome In this syndrome, conscious mental life is maintained, with loss of motor ability. Unable to move and communicate, the person becomes mentally locked in. The cause is typically damage to the pons of the metencephalon. Most victims retain eye movement ability. Some are entirely locked in. In these cases, functional magnetic resonance imaging (fMRI) scanners can be used during presentations of specific mental tasks to see if patients are solving them (Tshibanda 2010).
Connecting the midbrain, medulla, and synaptic centers for motor control, the pons is crucial for a wide array of functions, many of which are motor related. The cerebellum supports motor function and also cognition.