Presentation on theme: "Diencephalon, Brain Stem and Cranial Nerves"— Presentation transcript:
1 Diencephalon, Brain Stem and Cranial Nerves Day 5Pages:
2 DiencephalonLocated between the cerebral hemispheres and above midbrainComposed largely of gray matterSurrounds 3rd ventricleIncludes:ThalamusHypothalamusOptic tractsOptic chiasmaInfundibulumPosterior pituitary glandMammillary bodiesPineal gland
3 Parts to Diencephalon Optic tracts/optic chiasma Infundibulum Formed by optic nerve fibers crossing over each otherInfundibulumBehind optic chiasma, attachment for pituitary glandPosterior pituitary glandHangs from floor of hypothalamusMammillary BodiesTwo rounded structures behind infundibulumPineal glandCone shaped structure attached to upper portion of diencephalon
4 Thalamus Bulge into 3rd ventricle Central relay station for all sensory impulses except smell (ascending fibers)Channels impulses to appropriate regions of cortex for interpretationCan communicate with cerebral cortex by means of descending fibers
5 Hypothalamus Located below thalamus and forms floor of 3rd ventricle Maintains homeostasis and links endocrine to nervous systemRegulates:Heart rate and arterial BPBody Temp.H2O and electrolyte balanceControl of hunger and body weightControl movements and glandular secretions of stomach and intestinesProduction of neurosecretory substances and stimulation of pituitary gland to secrete hormonesSleep and wakefulness
6 Other functions of Diencephalon Limbic SystemComprised of parts of: cerebral cortex, frontal and temporal lobes, hypothalamus, thalamus basal ganglia and other deep masses called nucleiControls emotional experiences and expressionsCan modify the way a person actsFear, anger, pleasure, and sorrowGuides persons behavior towards a likely increase in survival.
7 Brain StemBundle of nervous tissue that connects cerebrum to spinal cord.Consists of three partsMidbrainPonsMedulla Oblongata
8 Midbrain Located at the top between diencephalon and pons Contain corticospinal tracts which are the main motor pathways between cerebrum and lower parts of nervous systemContains several masses of gray matter that serve as reflex centers.
9 Pons Rounded bulge on underside of brain stem Dorsal side relays impulses to and from M.O and cerebrum.Ventral side transmits impulses to cerebrum and cerebellum.Also relays sensory impulses from PNS to higher brain centers
10 Medulla Oblongata End of brain stem All ascending and descending nerve fibers pass through MOControls vital visceral activitesCardiac centerAlters heart rateVasomotor CenterConstricting and dilating of blood vesselsRespiratory CenterRegulate rate, rhythm, and depth of breathingAlso responsible for coughing, sneezing, swallowing and vomiting.
11 Reticular Formation Found throughout the brain stem Network of nerve fibersResponsible for taking sensory impulses and activating cerebral cortex into a state of wakefulnessDecreased activity in reticular formation is known as sleep.Comatose state:Point at which the reticular formation is injured and cannot be aroused even with strong stimulation.
12 Cerebellum Large mass of tissue located below occipital bone. Divided into two hemispheresSurrounded by cerebral cortexCommunicates with CNS by three pairs of nerve tractsCerebellar peduncles
13 Cellebellar Peduncles InferiorBrings sensory information concerning position of limbs, joints, and other body partsMiddleTransmits signals from the cerebral cortex to the cerebrellum concerning desired positions of these parts. After interpretation/analysis, sends pulses on to 3rd pairSuperiorIncorporated into motor impulses that get sent down brainstem to move body in desired way.
14 CerebellumReflex center for integrating sensory information concerning position of body parts and coordination of skeletal muscle movementsMaintains postureDamage/InjuryTremorsInaccurate movements of voluntarymusclesLoss of muscle toneReeling walkLoss of equilibrium
15 Review What are the major functions of the thalamus? The hypothalamus? How may the limbic system influence behavior?List the structures of the brain stem.What vital reflex centers are located in the brain stem?What is the function of the reticular formation?Where is the cerebellum located?What are the major functions of the cerebellum?