The most inferior part of the brain, the medulla oblongata, appears as a thickening of the spinal cord. Many of the cranial nerves originate here (see below). The medulla oblongata contains nuclei that control many basic functions, including the cardiac center, the vasomotor center, the respiratory centers, and many other involuntary functions such as swallowing, coughing, salivating, sweating, and gastrointestinal secretion.
In humans, the pons is the next most superior feature of the brain; the pons looks like a forward-facing bulge in the brainstem above the medulla oblongata. The pons relays signals between cerebrum and cerebellum, including sleep, hearing, taste, and posture to name a few. The cerebellum is a smaller, highly folded structure in the back of the brain, behind the pons. Like the cerebrum, it is split into hemispheres, with a flattened area down the center called the vermis. The folds are folia and grooves are sulci. The white matter forms a distinctive arbor vitae ("tree of life"). The cerebellum is concerned with muscular coordination, special perception, and tactile perception, and some planning and scheduling tasks. The midbrain is a small region of gray matter nuclei involved in different motor and sensory functions and connecting white matter pathways. These structures include: 1. Cerebral peduncles- anchor cerebrum to brainstem 2. Tegmentum- to/from cerebellum for motor control 3. Substantia nigra- inhibitory relay (the area destroyed in Parkinson disease) 4. Central gray matter- pain awareness 5. Tectum- include the inferior and superior colliculi for hearing and vision 6. Red nucleus- subconscious motor commands and muscle tone The reticular formation is a series of gray matter extensions from the midbrain through the cerebellum. They are involved in 1. Somatic motor control, including the pattern generators 2. Cardiovascular control 3. Pain modulation 4. Sleep and consciousness, including habituation