CENTRAL NERVOUS SYSTEM

1. CENTRAL NERVOUS SYSTEM

2. SUBDIVISIONS OF BRAIN 1. telencephalon surface gray - cerebrum cortex deep gray - basal nuclei white matter 2. diencephalon epithalamus thalamus hypothalamus

3. SUBDIVISIONS OF BRAIN 3. mesencephalon corpora quadrigemina cerebral peduncles substantia nigra red nucleus 4. metencephalon cerebellum pons 5. myelencephalon medulla oblongata olive

6. MENINGES a. dura mater double layer over most of brain outer periosteal layer inner meningeal layer separate by _______________ which empty into the internal jugular veins single layer over spinal cord epidural space between dural sheath and spinal cord

7. MENINGES b. arachnoid middle cob-web layer separated from dura mater by subdural space some feel this my be an artifact separated from pia mater by subarachnoid space 2 spaces contain __________fluid subarachnoid space is much larger arachnoid villi c. pia mater inner most delicate areolar connective tissue

9. THREE VENTRICLES 1. lateral ventricles in each cerebral hemisphere 1st two ventricles fuse to form the lateral ventricles connected to third ventricle by _______________ foramen 2. 3rd ventricle between left and right halves of the thalamus connected to 4th ventricle by mesencephalic (cerebral) __________ 3. 4th ventricle between inferior brain stem and the cerebellum connects to the spinal canal in the spinal cord

11. CEREBROSPINAL FLUID components very different from plasma low in proteins pH is lower K, Ca, HCO3 and glucose are lower Na is about the same

12. CEREBROSPINAL FLUID functions a. Buoyancy human brain weighs about 1500 g in air but 50 g when suspended in CSF b. Protection protects brain from striking the cranium c. Chemical Stability provides means of rinsing metabolic wastes from CNS and regulating its chemical environment

13. CEREBROSPINAL FLUID formation formed in the _______________ in roofs of the ventricles volume = 100 - 160 ml produce about 500 ml per day 160 mm pressure

14. CEREBROSPINAL FLUID pathway produced in roofs of all ventricles lateral ventricle --> interventricular foramen --> 3rd ventricle --> cerebral aqueduct --> 4th ventricle --> (central canal of spinal cord) --> subarachnoid space --> arachnoid villi --> dural sinus

16. CEREBROSPINAL FLUID lumbar puncture between L3 and L4 CSF from __________ space spinal tap: 3-9 ml myelogram epidural and spinal blocks into the epidural space steroids and anastethetics

17. BLOOD SUPPLY one - two minute interruption of blood may weaken cells brain constitutes 2% of adult body weight, receives 15% of blood and consumes 20% of body�s oxygen and glucose 4 minute interruption of blood, brains cells have permanent injury lysosomes release enzymes to break down brain cells brain cells _____ stored oxygen like myoglobin _____ energy reserves in the form of carbohydrates (glycogen) or lipids

18. BLOOD BRAIN BARRIER normal capillary bed is very permeable Two different barriers 1. blood brain barrier capillary bed has tight junctions protoplasmic __________ cover capillary and release chemicals that control the permeability of the endothelium 2. Blood-CSF barrier ependymal cells in choroid plexus have _______ junctions

19. BLOOD BRAIN BARRIER blood brain barrier pass easily water, glucose lipid soluble substances - oxygen, carbon dioxide, caffeine, nicotine, heroin, and anesthetics pass slowly sodium, potassium, chloride, creatinine, and urea do not pass proteins, most antibiotics neurotransmitters, formed elements

20. BLOOD BRAIN BARRIER not found portions of the hypothalamus posterior pituitary gland pineal gland choroid plexus by-pass bbb nasal sprays can travel up the olfactory nerve fibers

22. MYELENCEPHALON medulla oblongata 3 cm long (1 inch) forms inferior part of brain stem lateral side - Olive contains inferior olivary nuclei communicates with the cerebellum

24. MYELENCEPHALON three groups of nuclei (we will consider 2) 1. autonomic nuclei controlling visceral activities cardiac center vasomotor center two respiratory centers 2. relay stations along sensory or motor pathways nucleus gracilis and nucleus cuneatus sensory information crosses over decussation of pyramids descending motor tracts 2/3 of fibers cross over

25. RETICULAR FORMATION brain stem medulla + pons + mesencephalon contains more than 100 clusters of neurons dispersed gray matter functions 1. Somatic motor control 2. Cardiovascular control 3. Pain modulation 4. Sleep and consciousness

27. METENCEPHALON second largest part of the brain contains 50% of brain�s neurons two major areas a. cerebellum b. pons

28. METENCEPHALON a. cerebellum composed of two cerebellar hemispheres connected by the vermis gray matter cortex contains huge and highly branched Purkinje cells can receive input from up to 200,000 synapses

30. METENCEPHALON a. cerebellum white matter or arbor vitae superior cerebellar peduncles middle cerebellar peduncles inferior cerebellar peduncles

31. METENCEPHALON a. cerebellum functions 1. adjusting the postural muscles of the body coordinates rapid, automatic adjustments that maintain balance and equilibrium 2. programming and fine-tuning movements controlled at the conscious and subconscious levels refines learned movement patterns

32. METENCEPHALON b. pons links cerebellar hemispheres with mesencephalon, diencephalon, cerebrum and spinal cord contains nuclei involved with control of respiration nuclei and tracts that process and relay information heading to or from the cerebellum

33. MESENCEPHALON also called midbrain contains gray matter 1. corpora quadrigemina 2. red nucleus 3. substantia nigra 4. reticular formation

34. MESENCEPHALON contains white matter cerebral peduncles connect primary motor cortex with motor neurons in brain and spinal cord carry sensory information to thalamus

35. MESENCEPHALON 1. corpora quadrigemina superior colliculus initiates reflex response to visual stimuli inferior colliculus initiates reflex response to auditory stimuli 2. red nucleus contains iron and many blood vessels controls posture

36. MESENCEPHALON 3. substantia nigra darkly pigmented with melanin inhibits the activity of the cerebral nuclei by releasing dopamine associated with Parkinson�s disease 4. reticular formation reticular activating system maintenance of consciousness

38. DIENCEPHALON - THALAMUS structure two oval masses of nerve cell bodies 4/5 of diencephalon contains over 20 functionally separate nuclei functions �gateway to cerebral cortex� communicates cerebellum with the cerebrum nearly all sensory impulses pass through the thalamus passes only a small portion of arriving sensory information to cerebrum

39. DIENCEPHALON -HYPOTHALAMUS components numerous nuclei nuclei --> hormones preoptic areas --> body temperature, sexual behavior mammillary bodies --> controls feeding reflexes and processes motor information associated with eating, relays signals from limbic system to thalamus tuber cinereum --> nerve tracts that carry hormones to the pituitary infundibulum --> stalk that connects to posterior lobe of pituitary

40. DIENCEPHALON -HYPOTHALAMUS functions subconscious control of skeletal muscle contractions control of autonomic function secretion of hormones production of emotions and behavioral drive regulation of body temperature food and water intake control of circadian rhythm memory

41. DIENCEPHALON-EPITHALAMUS contains the pineal body producing the hormone _________________ functions - lower vertebrates regulates reproductive cycles based on photoperiod functions of melatonin in humans regulation of day-night cycles jet lag onset of sleep

42. TELENCEPHALON OR CEREBRUM components surface gray matter - neocortex 6 layers of nerve cell bodies deep gray matter - basal or cerebral nuclei white matter myelinated tracts features of cerebral cortex gyrus - fold in cortex sulcus - shallow groove fissure - deep groove

43. CEREBRUM - WHITE MATTER forms three myelinated tracts 1. projection tracts to and from other parts of the brain such as the thalamus 2. association tracts within the same hemisphere 3. commissural tracts connects left and right hemispheres a. anterior and posterior commissures b. corpus callosum 4 billion impulses per second

46. CEREBRUM - LOBES 1. Frontal voluntary control of skeletal muscle motivation, aggression, mood planning, social judgment, intelligence 2. Parietal major center for reception and evaluation of most sensory information excluding smell, hearing and vision including taste, touch, pressure, temperature, and pain 3. Occipital -- vision

47. CEREBRUM - LOBES 4. Temporal smell and hearing memory, visual recognition, emotional behavior 5. Insula part of limbic system plays a role in understanding spoken language, taste, and in integrating sensory information from visceral receptors

49. CEREBRUM - MOTOR AREASFRONTAL LOBE 1. Primary motor cortex controls precise voluntary contractions of skeletal muscle cells has pyramidal cells- origin of pyramidal tracts 2. Premotor cortex extrapyramidal tracts coordinates movement in sequence much of ones knowledge is stored here for controlling skilled movements 3. Broca�s area controls speech 19/20 are in the left hemisphere

50. CEREBRUM - SENSORY AREAS  Primary sensory cortex parietal lobe touch, pressure, temperature, and pain Visual cortex occipital lobe Auditory cortex (sound) temporal lobe Olfactory cortex (smell) temporal lobe Gustatory cortex (taste??) insula and frontal lobe

51. CEREBRUM - ASSOCIATION AREAS sensory and motor areas are connected to association areas regions of cortex that interpret incoming data or coordinate a motor response Association areas 1. Somatic sensory association area 2. Visual association area 3. Auditory association area

52. CEREBRUM - GENERAL INTERPRETIVE OR WERNICKE�S AREA description receive information from many association areas and direct complex motor activities perform complicated analytical functions forms one thought from other association areas meaning of written and spoken word found in temporal and parietal lobes only in left hemisphere

53. CEREBRUM - FRONTAL AREA Frontal lobe origin of higher intellectual activities, will judgement, personality, long term memory prefrontal lobe or cortex coordinates information relayed from association areas of entire cortex abstract intellectual functions feelings of frustration, tension, and anxiety are generated at prefrontal cortex prefrontal lobotomy treated for a variety of mental illnesses, especially those associated with violent or antisocial behavior

54. BRAIN LATERALIZATION generally left hemisphere contains general interpretive and speech centers and is responsible for language based skills premotor cortex is larger on the left side for right-handed people Left hemisphere - categorical hemisphere important for analytical tasks such as mathematical calculations and logical decision making more important in spoken and written language

55. BRAIN LATERALIZATION Right or representation hemisphere relates body to sensory environment can identify familiar objects by touch, smell, sight, taste or feel more for musical and artistic awareness

56. CEREBRAL NUCLEI functions subconscious control of skeletal muscle tone and coordination of learned movement patterns do not initiate particular movements but proved general pattern and rhythm extrapyramidal tracts loss of function - Parkinson�s disease leaves person with only crude motor activities movement of limbs stiff inhibits motor activities

57. LIMBIC SYSTEM functions establishes emotional states links the conscious, intellectual functions of the cerebral cortex with the autonomic functions of the brain stem facilitates memory storage and retrieval makes you want to do complex tasks -- called motivational system

59. SPINAL CORD general characteristics length - 45 cm (18 in) maximum width - 14 mm (0.55 in) enlargements cervical - C4 to T1 lumbar - T9 to T 12

60. SPINAL CORD general characteristics conus medullaris or medullary cone- 1st or 2nd lumbar terminal filum inferior tip of conus medullaris to 2nd sacral vertebra cauda equina appearance of horse�s tail from L2 to S5

61. SPINAL CORD - MENINGES a. dura mater continuous with dura mater of brain between dura mater and wall of vertebral column is epidural space filled with areolar connective tissue and blood vessels b. arachnoid subdural and subarachnoid spaces

62. SPINAL CORD - MENINGES c. pia mater adheres to surface of spinal cord and brain contains rich amount of blood vessels spinal cord is suspended in middle of dural sheath suspended by extensions of pia mater called denticulate ligaments protects cord against shock and sudden displacement

64. SPINAL CORD - COMPOSITION gray and white matter is reversed from brain H of gray matter gray commissure central canal posterior or dorsal horns anterior or ventral horns lateral horns (thoracic and lumbar regions) dorsal root ventral root

66. SPINAL CORD - WHITE MATTER a. ascending tracts - carry sensory information b. descending tracts - carry motor information

67. REFLEX ARC not all sensory impulses carried to spinal cord enter one of the ascending tracts to the brain some synapse directly or through association neurons with motor neurons in the anterior horn called a reflex arc presence of spinal reflex arc makes possible automatic stereotyped reactions to stimuli at same time a reflex is occurring, information about stimulus is also transmitted to brain

68. REFLEX ARC 1. receptor 2. sensory or afferent neuron 3. information processing - synapse monosynaptic polysynaptic 4. motor neuron 5. response - effector cardiac, skeletal or smooth muscle gland

70. SPINAL REFLEXMONOSYNAPTIC REFLEXSTRETCH REFLEX results when a muscle is stretched to counteract the stretch slight stretching stimulates receptors in muscle called neuromuscular spindles or intrafusal fibers 3 to 10 specialized muscles cells (central area does not contract) once spindle is stretched sends impulses to dorsal horn where it synapses with efferent neurons called alpha motor neurons alpha motor neurons send impulse to muscle causing contraction

71. SPINAL REFLEXMONOSYNAPTIC REFLEXSTRETCH REFLEX afferent neurons also synapse with inhibitory neurons inhibitory neurons synapse with efferent or motor neurons of the antagonistic muscles ex knee jerk reflex or patellar reflex maintaining balance - sends sends sensory impulses to cerebellum by away of the brainstem which integrates this information and relays it to the cerebral cortex