1. THE HUMAN BRAIN

2. THE AMAZING BRAIN!!! - the brain contains about 35 billion neurons! - all of our dreams, passions, memories, and plans are the result of brain activity - the brain contains about 98% of the neural tissue of the body - average brain weighs about 3 pounds - male brains are about 10 percent larger than female brains, but larger brains don’t indicate more intelligence!

3. DIVISIONS OF THE BRAIN There are 6 major regions of the adult brain: 1. Cerebrum 2. Diencephalon 3. Midbrain 4. Pons 5. Medulla oblongata 6. Cerebellum

4. SOME QUICK FACTS: 1. CEREBRUM - Can be divided into paired CEREBRAL HEMISPHERES - conscious thoughts, sensations, intellectual functions, memory storage and retrieval, and complex movements originate here 2. DIENCEPHALON - hollow, connected to cerebrum

5. - its sides form the THALAMUS, which contains relay and processing centers for sensory info - HYPOTHALAMUS (floor of diencephalon) is connected to the pituitary gland - hypothalamus contains centers involved with emotions, autonomic function, and hormone production - pituitary gland links the nervous and endocrine systems

6. 3. MIDBRAIN - along with pons and medulla oblongata, forms the BRAIN STEM - nuclei in the midbrain process visual and auditory info and generate involuntary motor responses - also contains centers that maintain consciousness

7. 4. PONS - acts like a bridge to connect the cerebellum to the brain stem - contains nuclei involved with somatic and visceral motor control - also connected to medulla oblongata 5. MEDULLA OBLONGATA - attached to spinal cord - relays sensory info to thalamus and other brain stem centers

8. - contains centers that regulate heart rate, blood pressure, respiration, and digestive activities 6. CEREBELLUM - adjusts voluntary and involuntary motor activities on the basis of sensory info and stored memories of previous movements

9. Ventricles The brain has a central passageway that expands to form 4 chambers- VENTRICLES - Each hemisphere contains a large LATERAL VENTRICLE * there is no direct connection between the 2, but an opening called the interventricular foramen allows each to communicate with the THIRD VENTRICLE

10. - The midbrain has a slender canal called the mesencephalic aqueduct which connects the third ventricle with the FOURTH VENTRICLE * in the medulla oblongata, the fourth ventricle narrows and becomes continuous with the central canal of the spinal cord

11. Cerebrospinal Fluid (CSF) Surrounds and bathes exposed surfaces of CNS - cushions delicate neural structures - supports- the brain floats in CSF - can be drawn to diagnose injury, infection, or disease - produced at CHOROID PLEXUS, a network of capillaries that extend into each ventricle - entire volume of CSF is replaced every 8 hours

12. Cerebrum The cerebrum is the largest region of the brain, and the site where conscious thought and intellectual functions originate - contains gray and white matter

13. STRUCTURE OF CEREBRUM CEREBRAL CORTEX- covers superior and lateral surfaces of cerebrum - this outer surface forms a series of elevated ridges or GYRI, which are separated by shallow depressions called SULCI, or deeper grooves called FISSURES The 2 HEMISPHERES are separated by a deep longitudinal fissure - extending laterally from the longitudinal fissure is a deep groove called the CENTRAL SULCUS

14. Each hemisphere can be divided into lobes - named after overlying bones of skull - in each lobe, some regions are concerned with sensory info. and others with motor commands Each hemisphere receives sensory info. from and sends motor commands to opposite sides of the body

15. MOTOR AND SENSORY AREAS OF CORTEX The central sulcus separates motor and sensory portions of the cortex - PRECENTRAL GYRUS- surface is the primary motor cortex * here neurons direct voluntary movements by controlling somatic motor neurons in the brain stem and spinal cord - POSTCENTRAL GYRUS- contains primary sensory cortex

16. * neurons here receive somatic sensory information from touch, pressure, pain, and temperature receptors Other sensations arrive at other portions of the cortex: - visual cortex - gustatory cortex (taste) - auditory cortex - olfactory cortex (smell)

17. ASSOCIATION AREAS OF THE CORTEX Sensory and motor regions of the cortex are connected to association areas that interpret incoming data or coordinate a motor response SOMATIC SENSORY ASSOCIATION AREA - monitors activity in the primary sensory cortex - allows you to recognize a very light touch

18. SOMATIC MOTOR ASSOCIATION AREA - responsible for coordinating learned movements

19. CORTICAL CONNECTIONS Regions of cortex are interconnected by the white matter below - the white matter interconnects areas within a single cerebral hemisphere and links the 2 hemispheres across the CORPUS CALLOSUM

20. PROCESSING CENTERS OF CORTEX There are “higher-order” integrative centers that receive information through axons from many different association areas - these areas control extremely complex motor activities and perform complicated analytical functions 1. GENERAL INTERPRETIVE AREA - receives info. from all sensory association areas - is present only in 1 hemisphere (usually left)

21. - damage to this area effects ability to interpret what is read or heard 2. SPEECH CENTER - regulates patterns of breathing and vocalization needed for normal speech - damage can cause difficulty speaking even when you know which words to use; or talking constantly but using the wrong words

22. 3. PREFRONTAL CORTEX - coordinates info. from association areas of the entire cortex - performs abstract functions like predicting future consequences of events or actions - damage leads to problems in estimating time relationships between events

23. A QUICK LESSON ON MEMORY…. FACT MEMORIES are specific bits of info. - such as the color of a stop sign SKILL MEMORIES are learned behaviors - such as tying your shoes 2 Classes of memories: 1. SHORT–TERM- do not last long, but can be recalled immediately - Ex: phone number

24. 2. LONG-Term- remain for much longer * the conversion from short to long is called MEMORY CONSOLIDATION * most long-term memories are stored in the cerebral cortex AMNESIA- loss of memory from disease or trauma - type of memory loss depends on the regions of the brain affected

25. Basal Nuclei The basal nuclei direct activities that are outside of our conscious awareness - they are masses of gray matter that lie below the lateral ventricles and within the white matter of each cerebral hemisphere COMPONENTS: 1. Caudate Nucleus 2. Lentiform Nucleus- lies below caudate nucleus * globus pallidus * putamen

26. 3. Amygdaloid body- lies below the lentiform nucleus The basal nuclei are involved with the subconscious control of skeletal muscle tone and coordination of learned movement patterns - they do NOT begin a movement, but provide pattern and rhythm once a movement is started

27. http://www.colorado.edu/kines/Class/IPHY3730/image/figure5-31.jpg

28. Limbic System The LIMBIC SYSTEM includes the olfactory cortex, several basal nuclei, gyri, and tracts along the border of the cerebrum and diencephalon FUNCTIONS: 1. Establishing emotional states and related behavioral drives 2. Linking conscious functions of cerebral cortex with unconscious functions of brain stem

29. 3. Long-term memory storage and retrieval * damage to HIPPOCAMPUS that occurs in Alzheimer’s interferes with memory storage and retrieval The limbic system also includes hypothalamic centers that control: - emotional states- rage, fear, sexual arousal - reflex movements that can be consciously activated (chewing, swallowing)

30. http://general.rau.ac.za/psych/Resources/Honours/Neuropsych/Downloads/downloadstr/Lect2- opt/limbic%20system.jpg

31. Diencephalon The DIENCEPHALON provides switching and relay centers that integrate conscious and unconscious sensory info. and motor commands 3 COMPONENTS: 1. EPITHALAMUS - forms roof of diencephalon - contains PINEAL GLAND- endocrine structure that secretes the hormone MELATONIN

32. 2. THALAMUS - final relay point for all ascending sensory info. other than olfactory that will reach our conscious awareness - acts as a filter, passing on to the primary sensory cortex only a small portion of arriving sensory info. - also plays a role in coordinating voluntary and involuntary motor commands

33. 3. HYPOTHALAMUS - contains important control and integrative centers in addition to those associated with the limbic system MANY DIVERSE FUNCTIONS: - subconscious control of skeletal muscle contractions associated with rage, pleasure, pain

34. - adjusting activities of autonomic centers of pons and medulla oblongata (heart rate, blood pressure) - secreting hormones - producing behavioral drives involved in hunger and thirst - regulating normal body temperature

35. Midbrain The MIDBRAIN contains 2 pairs of sensory nuclei or COLLICULI dealing with processing of visual and auditory sensations - SUPERIOR COLLICULI- controls reflex movements of eyes, head, and neck in response to visual stimuli (flash of light) - INFERIOR COLLICULI- control reflex movements of head, neck and trunk to auditory stimuli (loud noise)

36. Descending bundles of nerve fibers make up the CEREBRAL PEDUNCLES The midbrain contains the RETICULAR FORMATION, which regulates many involuntary functions - contains the reticular activation system (RAS) which directly affects the activity of the cerebral cortex - when RAS is inactive, so are we

37. http://www.stanford.edu/group/hopes/rltdsci/trinuc/f_f10midcereb.jpg

38. Pons The PONS links the cerebellum with the midbrain, diencephalon, cerebrum, and spinal cord

39. Cerebellum The CEREBELLUM is an automatic processing center 2 IMPORTANT FUNCTIONS: 1. Adjusting postural muscles of body to maintain balance 2. Programming and fine-tuning movements controlled at conscious and subconscious levels

40. - the cerebellum compares motor commands with proprioceptive info. (position sense) and performs adjustments needed to make movement smooth - tracts that link the cerebellum with these different regions are the CEREBELLAR PEDUNCLES - cerebellum can be permanently damaged by trauma, stroke, and drugs- produce ATAXIA (disturbance in balance)

41. Medulla Oblongata The MEDULLA OBLONGATA connects the brain with the spinal cord - all communication between the brain and spinal cord involves tracts that ascend or descend through the medulla oblongata * CARDIOVASCULAR CENTERS- adjust heart rate, strength of cardiac contractions, and flow of blood * RESPIRATORY RHYTHMICITY CENTERS- set basic pace for respiratory movements

42. PEREPHERAL NERVOUS SYSTEM

43. PNS The PERIPHERAL NERVOUS SYSTEM (PNS) is the link between the neurons of the central nervous system (CNS) and the rest of the body - all sensory information and motor commands are carried by axons of the PNS - these axons, bundled together and wrapped in connective tissue, form PERIPHERAL NERVES

44. Cranial nerves originate from the brain and spinal nerves connect to the spinal cord - the PNS also contains both the cell bodies and the axons of sensory neurons and motor neurons of the autonomic nervous system

45. Cranial Nerves There are 12 pairs of CRANIAL NERVES that connect to the brain - they are numbered according to their position along the longitudinal axis of the brain - you will label and identify the functions of these nerves

46. Spinal Nerves There are 31 pairs of spinal nerves that can be grouped according to the region of the vertebral column from which they originate - 8 pairs of cervical nerves - 12 pairs of thoracic nerves - 5 pairs of lumbar nerves - 5 pairs of sacral nerves - 1 pair of coccygeal nerves

47. Each pair of spinal nerves monitors a specific region of the body surface known as a DERMATOME - dermatomes are clinically important because damage or infection of a spinal nerve or dorsal root ganglia will produce a characteristic loss of sensation in specific parts of the skin

48. http://anatomy.med.umich.edu/modules/spinal_cord_module/Files/SC_cnspnsimg.jp g

49. http://www.stephblog.com/dermatomes.jpg