1. Diencephalon, Brain Stem and Cranial Nerves
Day 5
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2. Diencephalon
Located between the cerebral hemispheres and above midbrain
Composed largely of gray matter
Surrounds 3rd ventricle
Includes:
Thalamus
Hypothalamus
Optic tracts
Optic chiasma
Infundibulum
Posterior pituitary gland
Mammillary bodies
Pineal gland

3. Parts to Diencephalon Optic tracts/optic chiasma Infundibulum
Formed by optic nerve fibers crossing over each other
Infundibulum
Behind optic chiasma, attachment for pituitary gland
Posterior pituitary gland
Hangs from floor of hypothalamus
Mammillary Bodies
Two rounded structures behind infundibulum
Pineal gland
Cone 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 interpretation
Can 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 system
Regulates:
Heart rate and arterial BP
Body Temp.
H2O and electrolyte balance
Control of hunger and body weight
Control movements and glandular secretions of stomach and intestines
Production of neurosecretory substances and stimulation of pituitary gland to secrete hormones
Sleep and wakefulness

6. Other functions of Diencephalon
Limbic System
Comprised of parts of: cerebral cortex, frontal and temporal lobes, hypothalamus, thalamus basal ganglia and other deep masses called nuclei
Controls emotional experiences and expressions
Can modify the way a person acts
Fear, anger, pleasure, and sorrow
Guides persons behavior towards a likely increase in survival.

7. Brain Stem
Bundle of nervous tissue that connects cerebrum to spinal cord.
Consists of three parts
Midbrain
Pons
Medulla 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 system
Contains 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 MO
Controls vital visceral activites
Cardiac center
Alters heart rate
Vasomotor Center
Constricting and dilating of blood vessels
Respiratory Center
Regulate rate, rhythm, and depth of breathing
Also responsible for coughing, sneezing, swallowing and vomiting.

11. Reticular Formation Found throughout the brain stem
Network of nerve fibers
Responsible for taking sensory impulses and activating cerebral cortex into a state of wakefulness
Decreased 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 hemispheres
Surrounded by cerebral cortex
Communicates with CNS by three pairs of nerve tracts
Cerebellar peduncles

13. Cellebellar Peduncles
Inferior
Brings sensory information concerning position of limbs, joints, and other body parts
Middle
Transmits signals from the cerebral cortex to the cerebrellum concerning desired positions of these parts. After interpretation/analysis, sends pulses on to 3rd pair
Superior
Incorporated into motor impulses that get sent down brainstem to move body in desired way.

14. Cerebellum
Reflex center for integrating sensory information concerning position of body parts and coordination of skeletal muscle movements
Maintains posture
Damage/Injury
Tremors
Inaccurate movements of voluntary
muscles
Loss of muscle tone
Reeling walk
Loss 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?