Exam 4 Review:  Chapter 12:  Cerebellum & Brain Stem

tentorium cerebelli - A fold of the dura mater forming a roof over the cerebellum within the posterior cranial fossa, except for an anterior median opening through which the mesencephalon passes, and separating the cerebellum from the basal surface of the occipital and temporal lobes of the cerebral cortex; it supports the occipital lobes of the cerebrum, and has its posterior and lateral border attached to the skull and its anterior border free.

folia - The folds of gray matter which form the cerebellar hemispheres; having the gray matter distributed in folds and grooves increases the surface area of the cortex to make room for additional neurons, and to facilitate diffusion of nutrients, respiratory gases, and wastes between the nervous tissue and the adjacent cerebrospinal fluid and the blood stream.

arbor vitae - The white matter or myelinated nerve tissue of the cerebellum, which has a treelike outline in a median section.

falx cerebelli - The smaller of the two folds of dura mater separating the hemispheres of the brain that lies between the lateral lobes of the cerebellum; a short process of dura mater projecting from the internal occipital crest below the tentorium, and bifurcating into two diverging limbs passing to either side of the foramen magnum.

reticular formation - A diffuse network of nerve fibers and neurons collected in various nuclei in parts of the brainstem, which receives afferent axons from a variety of sources, especially from the face; this system is important in arousal, maintaining consciousness, wakefulness and muscle tone and contributes to sensory adaptation by filtering out repetitive stimuli.

reticular activating system - The combination of the reticular formation in the brain stem and its connections which functions to produce arousal by responding to sensory stimuli (visual, auditory, cutaneous, olfactory, etc.) with impulses sent to higher centers; this system is suppressed by general anesthetic gases; efferent impulses are also transferred in descending pathways to control respiratory and cardiac rhythms.

cardiovascular center - A major autonomic nucleus located deep inside the medulla which received visceral sensory information about blood pressure, blood oxygen levels, blood pH, etc., and integrates this information to regulate the rate of the heartbeat and the level of muscular tension in the blood vessels primarily via sympathetic impulses.

medullary rhythmicity area - A collection of neurons in the reticular formation within the medulla oblongata involved in establishing or modifying the pattern for breathing; within this area are two key components:  (1) the ventral respiratory group (VRG) (formerly the inspiratory area) which autorhythmically stimulates spontaneous ventilation, resting or tidal breathing (eupnea), and (2) the dorsal respiratory group (DRG) (formerly the expiratory area) which responds to situations beyond those of the resting or tidal breathing (eupnea) to alter the pattern for ventilation in response to the physiological needs of the body for O₂ and CO₂ exchange and for blood acid-base balance.

pontine respiratory center (formerly pneumotaxic and apneustic areas) - A collection of neurons in the reticular formation within the pons which limit inspiratory duration by sending inhibitory signals to the medullary rhythmicity area reducing duration of inspiratory impulses causing shorter cycles which increases ventilation rate; these pontine respiratory neurons receive input from higher brain centers and peripheral receptors, and their output fine tunes the breathing rhythm during activities such as speaking, sleeping, or exercising.

substantia nigra - A layer of large pigmented nerve cells in the midbrain (mesencephalon) which produce dopamine and whose destruction is associated with Parkinson's disease; it is involved in metabolic disturbances associated with Parkinson's disease and with Huntington's disease.

List

7.  Six aspects of internal homeostasis coordinated by the medulla oblongata.

          1.  heart rate                                  4.  the vomiting reflex

          2.  blood vessel diameter               5.  the cough reflex

          3.  respiratory rate and depth         6.  control of swallowing

8.  Three types of sensory information integrated by the cerebellum.

          proprioception  --  visual information -- equilibrium (static and dynamic)

9. Three parts of the brain stem and an important functional area associated with each.