Lecture 17Outline of Last Lecture A. Other primary sensory areas of the cerebral cortexB. Architecture of the cerebral cortexC. Association areas of the cerebral cortexD. Voluntary motor output of the cerebral cortexii. The Telencephalona. Limbic lobeb. Basal ganglia II. Diencephalon a. Thalamusb. Hypothalamus III. MesencephalonOutline of Current LectureI. MentencephalonII. The PonsIII. MyelencephalonIV. Cerebrospinal Fluid Current LectureI. Metencephalona. 2 parts the cerebellum and ponsb. Cerebellumi. The cortex of the cerebellum help maintain our balance and posture ii. It determines how to coordinate and smooth out movements of the bodyiii. The cortex is folded into ridges and grooves 1. The ridges: folia2. The grooves: fissures iv. the cerebellar cortex is a layer of gray matter, and is underlain by white matter that consists of the axons leaving and entering the cortexv. deep to the white matter, near the 4th ventricle, is gray matter = deep cerebellar nuclei1. has a gray-white-gray layering pattern (just like the cerebrum)c. Inputs to the cerebellumi. Input A: sense of balance (equilibrium)1. The cerebellum must know where the body is locateda. Provided by sense of balance2. the balance receptors are specialized epithelial cells in the inner ear  receptor cells synapse with sensory neurons that run in the VIII cranial nerve  extend to the brain  axons synapse with neurons in the medulla oblongata  neurons relay information about balance to the cerebellar cortexii. Input B: muscle and tendon stretch BIOL_315 1nd Edition1. Information carried up spinal cord by the spinocerebellar tracts about tension in tendons and skeletal muscles of the body cerebellum 2. Cerebellum can gauge the current positions and movements of all body parts 3. Needs to know how our body parts move, in order to calculate how to coordinate the movementsiii. Input C: preview of the voluntary movements ordered by the primary motor cortex1. The cerebellum does not initiate or direct our movements, only smoothes and coordinates them.2. Movements are initiated by the primary motor region of the cerebral cortex and by some minor brain nuclei 3. The motor cerebral cortex dictates body movements to the spinal cord’s motor neurons, but first gives the cerebellum a preview of the planned movements 4. Then the cerebellum compares this plan with what it knows aboutbalance and determines whether the movements planned by the cerebral motor cortex are approx. coordinated a. If not, the cerebellum calculates how to smooth things out then informs the cerebrum how to do so5. Primary motor cerebral cortex sends information to the cerebelluma. Via pyramidal-tract axons , with nuclei in the pons then acting as relay nuclei iv. The cerebellum receives visual information from the eyes via the superiorcolliculi d. Internal structure of the cerebellumi. All incoming axons influence a major type of neuron in the cerebellar cortex, the Purkinje neuron1. very complex branching dendrites receive 2. these neurons communicate with each other, integrate all types ofsensory inputs, create a blueprint for coordinated movement, and dictate the output from the cerebellum3. their axons run down through the white matter of the cerebellum and relay information to through the deep cerebellar nucleie. outputs from the cerebellumi. axons from the above nuclei carry the cerebellar output up to the cerebral motor cortex and to some other parts of the brain ii. the cerebellum does not directly influence body movements, instead the cerebellum relays its output to other brain centers that do exert direct control over movements, especially the primary motor region of the cerebral cortexf. the cerebellar pedunclesi. cerebellar peduncles are pillars that connect the cerebellum to the dorsalpart of the brain stem, tracts of fibers carrying cerebellar inputs and outputsii. inferior cerebellar peduncles: consist of axons from the vestibular nuclei and the axons of the spinocerebellar tract, carrying information on balance and on proprioception to the cerebellumiii. middle cerebellar peduncles: huge tracts carry the information from the primary motor cerebral cortex to the cerebellum, the fibers in the middle peduncle arise in the pontine nuclei of the pons, from neurons that have received input from the cerebral cortexiv. superior cerebellar peduncles: fibers in the superior peduncles convey the outputs from the cerebellum rostrally toward the cerebral motor cortex** the inferior and middle peduncles carry inputs to the cerebellum, whilethe superior peduncles convey outputs from the cerebellum**II. The Ponsa. Brain-stem part of the metencephalonb. Ventral to the cerebellumc. Gray matter surrounds the ventricle, and deep-lying gray compromises the nucleiof cranial nervesd. Scattered in white matter of the pons, series of small nuclei of reticular formatione. Pontine nuclei: a cluster of small nuclei scattered throughout the ventral white matter i. Collectively, large in sizeii. Cause the floor of the pons to bulge forward iii. Receive information from the motor cerebral cortexiv. Axons project to the cortex of cerebellum via middle cerebellar pedunclesv. Relay nuclei in the pathway by which the motor cerebral cortex communicates with the cerebellum III. Myelencephalon (medulla oblongata)a. Part of the brain stem that most closely resembles the spinal cordb. Heavily involved in the innervation of a specific body region c. The head is innervated by cranial nerves d. Gray matter surrounding the 4th ventricle of the medulla comprises the nuclei of these cranial nervese. Also performs some complex functions that affect wider regions of the bodyi. Specifically, the olives, pyramids, and reticular formation1. Olives: olive-shaped bump on the side of the medulla, contains the inferior olivary nucleus, which is a relay nucleus along the spinocerebellar pathway 2. Pyramid: the pyramids are paired longitudinal ridges on the ventral part of the medulla near the midline3. Reticular formation: occupies much of the central core of the brain stem, runs continuously through the midbrain, pons, andmedulla. Consists of scattered loosely grouped bunches of neuron cell bodies plus many small nuclei imbedded in what would otherwise be considered white matter, external and ventral to the nuclei of the cranial nerves. Has many functions:a. Visceral functions: contain relay nuclei in the pathway by which the hypothalamus influences the ANSi. Hypothalamus