Anatomy of the Brain

1. Anatomy of the Brain

2. Overview • Size: ~ 3 pounds (~size of 2 fists) • Appearance: pinkish gray & wrinkled with a texture of cold oatmeal • # of Neurons: ~100 billion

3. Miscellaneous Facts • Brain = organ • Mind = abstract mental activity • Most of what we know of brain & mind learned through animal experiments and studying people with disease or head trauma • The brain has no pain receptors

4. Basic Definitions • Ventricles - cavities in the brain that contain CSF • Gyri (“twisters”) - elevated ridges of brain tissue • Sulci (“furrows”) - shallow grooves in brain tissue • Fissures - deep grooves that separate large regions of the brain

5. Basic Definitions (cont.) • Center - group of functionally related neurons that may or may not be closely grouped • Tract - a bundle of axons in the CNS that have the same origin & function • Basal nuclei - “islands” of gray matter located deep within the white matter of the cerebral hemispheres; help regulate voluntary motor areas

6. 4 Major Parts of the Brain • There are 4 major parts: cerebrum, diencephalon (interbrain), brainstem, & cerebellum

7. Parts of the Brain • Cerebrum - largest part of brain ~2 lbs. a. Consists of right & left hemispheres, separated by a longitudinal fissure

8. Parts of the Brain • Cerebrum - largest part of brain ~2 lbs. b. Contains the corpus callosum: a large fiber tract that connects the right & left hemisphere (Split-brain experiments)

9. Parts of the Brain • Lobes of each cerebral hemisphere 1. Frontal - speech, voluntary movement, & personality

10. Video Clip • Phineas Gage Story

11. Parts of the Brain • Lobes of each cerebral hemisphere 2. Parietal - interprets sensory functions such as touch (hot, cold, pain, pressure, & position of other body parts)

12. Parts of the Brain • Lobes of each cerebral hemisphere 3. Occipital - interpretation of vision 4. Temporal - interpretation of hearing, smell, & taste

13. Parts of the Brain • Cerebral cortex: - layer of gray matter that covers the cerebrum - highly wrinkled to increase surface area -main area of judgment, intelligence, creativity, memory, learning, & reasoning (Contains Broca’s area & Wernicke’s area - important speech centers)

14. Parts of the Brain • Diencephalon (Interbrain) - enclosed by the cerebral hemispheres and sits on top of the brain stem a. Thalamus - relay station for sensory impulses (recognize whether a sensation being passed along is pleasant or unpleasant)

15. Parts of the Brain b. Hypothalamus (“under the thalamus”) -responsible for autonomic/visceral control such as regulating body temperature, water balance, & metabolism -Limbic system “emotional-visceral brain”: controls hunger, thirst, sex, pain, & pleasure centers -Also allows for physical expression of emotion -Regulates the pituitary gland

16. Parts of the Brain c. Epithalamus - contains the pineal body (part of endocrine system) and a choroid plexus (helps form CSF)

17. Parts of the Brain • Brainstem - ~3 inches long & thumb size in diameter a. Midbrain - contains visual & auditory centers & nerve pathway crossing b. Pons (“bridge”) - responsible for autonomic functions such as respiration, jaw movement, & facial senses

18. Parts of the Brain c. Medulla oblongata - enlarged continuation of spinal cord; respiratory & cardiac control; autonomic reflexes such as sneezing, coughing, blinking, swallowing, & vomiting *Reticular Activating System (RAS) - sleep/wake cycle Lack of dreams = heading for severe psychological disturbance Lack of sleep = may result in insanity &/or death

19. Parts of the Brain • Cerebellum - 2nd largest part of brain; cauliflower-like structure -is also divided into right & left hemispheres -controls balance, posture, muscle tone, & coordination of movement

20. Parts of the Brain *Ataxia - damage to cerebellum (blow to head, tumor, stroke); movements are clumsy & disorganized; victims appear drunk due to loss of muscle coordination; cannot touch finger to nose with eyes closed

21. Review Song • Parts of the Brain Song