Chapter 10 The Nervous System: The Brain and Cranial Nerves

Transcription

1 Chapter 10 The Nervous System: The Brain and Cranial Nerves Copyright 2015 Wolters Kluwer Health Lippincott Williams & Wilkins

2 Overview

3 Key Terms aphasia corpus callosum meninges basal nuclei diencephalon midbrain brain stem electroencephalograph (EEG) pons cerebellum gyrus (pl. gyri) reticular formation cerebral cortex hematoma seizure cerebrospinal fluid (CSF) hypothalamus stroke cerebrum limbic system sulcus (pl. sulci) concussion medulla oblongata thalamus ventricle

4 Overview of the Brain Learning Objectives 1. Give the locations of the four main divisions of the brain. 2. Name and describe the three meninges. 3. Cite the function of cerebrospinal fluid, and describe where and how this fluid is formed.

5 The Cerebrum Learning Objectives 4. Name and locate the lobes of the cerebral hemispheres. 5. Cite one function of the cerebral cortex in each lobe of the cerebrum.

6 The Diencephalon Learning Objective 6. Name two divisions of the diencephalon, and cite the functions of each.

7 The Brain Stem Learning Objective 7. Locate the three subdivisions of the brain stem, and give the functions of each.

8 The Cerebellum Learning Objectives 8. Describe the cerebellum, and identify its functions. 9. Name three neuronal networks that involve multiple regions of the brain, and describe the function of each.

9 Brain Studies Learning Objective 10. Describe four techniques used to study the brain.

10 Disorders of the Brain and Associated Structures Learning Objective 11. Describe at least six disorders that affect the brain.

11 Cranial Nerves Learning Objectives 12. List the names and functions of the 12 cranial nerves. 13. Discuss five disorders that involve the cranial nerves.

12 Case Study Learning Objective 14.Using information in the case study, list the possible effects of mild traumatic brain injury.

13 Word Anatomy Learning Objective 15.Show how word parts are used to build words related to the nervous system.

14 Overview of the Brain Division Description Functions Cerebrum Largest and most superior portion of the brain Divided into two hemispheres; each subdivided into lobes Diencephalon Between the cerebrum and the brain stem Contains the thalamus and hypothalamus Cortex (outer layer) is site for conscious thought, memory, reasoning, and abstract mental functions, all localized within specific lobes. The thalamus sorts and redirects sensory input. The hypothalamus maintains homeostasis; controls the autonomic nervous system and pituitary gland.

15 Overview of the Brain (cont.) Division Description Functions Brain stem Midbrain Pons Medulla oblongata Cerebellum (means little brain ) Anterior region below the cerebrum Below center of the cerebrum Anterior to the cerebellum Between the pons and spinal cord Below the posterior portion of the cerebrum Divided into two hemispheres Connects the cerebrum and diencephalon with the spinal cord Has reflex centers concerned with vision and hearing Connects the cerebrum with lower portions of the brain Helps regulate respiration Links the brain with spinal cord Centers for control of vital functions Coordinates voluntary muscles Maintains balance and muscle tone

16 Overview of the Brain (cont.) Figure 10-1 Brain, sagittal section. What is the largest part of the brain? What part connects with the spinal cord?

17 Overview of the Brain (cont.) Protective Structures of the Brain and Spinal Cord Meninges Dura mater Dural sinuses Arachnoid Pia mater

18 Overview of the Brain (cont.) Figure 10-2 Frontal (coronal) section of the top of the head. The meninges and related parts are shown. What are the channels formed where the dura mater divides into two layers? How many layers of meninges are there?

19 Overview of the Brain (cont.) Protective Structures of the Brain and Spinal Cord (cont.) Cerebrospinal fluid (CSF) Supports nervous tissue, cushions from shock Carries nutrients to cells Transports waste products from cells Produced in ventricles Choroid plexus Lateral ventricles Foramina Cerebral aqueduct

20 Overview of the Brain (cont.) Protective Structures of the Brain and Spinal Cord (cont.) Ventricles Four fluid-filled spaces within the brain Lateral (two) Third Fourth Contain choroid plexus, which manufactures CSF Supports nervous tissue, cushions from shock Carries nutrients to cells Transports waste products from cells

21 Overview of the Brain (cont.) Figure 10-3 Cerebrospinal fluid (CSF) and the cerebral ventricles. Which ventricle is continuous with the central canal of the spinal cord?

22 Overview of the Brain (cont.) Checkpoints 10-1 What are the main divisions of the brain? 10-2 What are the names of the three layers of the meninges from the outermost to the innermost? 10-3 Where is CSF produced?

23 Overview of the Brain (cont.) Pop Quiz 10.1 Which division of the brain is physically connected to the spinal cord? A) Brain stem B) Cerebellum C) Cerebrum D) Diencephalon

24 Overview of the Brain (cont.) Pop Quiz Answer 10.1 Which division of the brain is physically connected to the spinal cord? A) Brain stem B) Cerebellum C) Cerebrum D) Diencephalon

25 The Cerebrum Learning Objectives 4. Name and locate the lobes of the cerebral hemispheres. 5. Cite one function of the cerebral cortex in each lobe of the cerebrum.

26 The Cerebrum (cont.) Divisions of the Cerebral Hemispheres The cerebrum is divided into two cerebral hemispheres. Each hemisphere is divided into five lobes: Frontal Parietal Temporal Occipital Insula

27 The Cerebrum (cont.) The Cerebral Hemispheres Outer layer of nervous tissue is called the cortex. Cortex arranged into folds: Gyri Sulci Central sulcus Lateral sulcus

28 The Cerebrum (cont.) The Cerebral Hemispheres (cont.) The internal layer is composed primarily of white matter. Corpus callosum bridges cerebral hemispheres.

29 The Cerebrum (cont.) Figure 10-4 External surface of the brain. What structure separates the frontal from the parietal lobe? The temporal lobe from the frontal and parietal lobes?

30 The Cerebrum (cont.) Functions of the Cerebral Cortex Lobe Frontal Parietal Temporal Occipital Description Contains motor area and speech centers Contains sensory areas Contains auditory, speech comprehension, and olfactory areas Contains visual association areas

31 The Cerebrum (cont.) Figure 10-5 Functional areas of the cerebral cortex. What cortical area is posterior to the central sulcus? What area is anterior to the central sulcus?

32 The Cerebrum (cont.) Memory and the Learning Process Short-term memory Information lost unless reinforced Long-term memory Rehearsal (repetition) Alertness

33 The Cerebrum (cont.) Checkpoints 10-4 Name the four surface lobes of each cerebral hemisphere Name the thin outer layer of gray matter where higher brain functions occur.

34 The Cerebrum (cont.) Pop Quiz 10.2 Which lobes are separated by the central sulcus? A) Frontal and parietal B) Parietal and occipital C) Temporal and occipital D) Temporal and frontal

35 The Cerebrum (cont.) Pop Quiz Answer 10.2 Which lobes are separated by the central sulcus? A) Frontal and parietal B) Parietal and occipital C) Temporal and occipital D) Temporal and frontal

36 The Diencephalon Learning Objective 6. Name two divisions of the diencephalon, and cite the functions of each.

37 The Diencephalon (cont.) Thalamus Sorts sensory impulses Directs impulses within the cerebral cortex Hypothalamus Maintains homeostasis Controls sympathetic and parasympathetic divisions of the autonomic nervous system Influences heartbeat, blood flow, hormone secretion

38 The Diencephalon (cont.) Figure 10-6 The diencephalon, brain stem, and cerebellum. To what part of the brain is the pituitary gland attached?

39 The Diencephalon (cont.) Checkpoint 10-6 What are the two main portions of the diencephalon, and what do they do?

40 The Diencephalon (cont.) Pop Quiz 10.3 Which structure controls the autonomic nervous system and the pituitary gland? A) Basal ganglia B) Cerebellum C) Hypothalamus D) Thalamus

41 The Diencephalon (cont.) Pop Quiz Answer 10.3 Which structure controls the autonomic nervous system and the pituitary gland? A) Basal ganglia B) Cerebellum C) Hypothalamus D) Thalamus

42 The Brain Stem Learning Objective 7. Locate the three subdivisions of the brain stem, and give the functions of each.

43 The Brain Stem (cont.) Composed of the midbrain, pons, and medulla oblongata Connects the cerebrum and diencephalon with the spinal cord

44 The Brain Stem (cont.) Midbrain Superior part of the brain stem Four masses form superior part of the midbrain House reflexes involving eyes and ears Conducts impulses between higher centers of the cerebrum and lower centers of the pons, medulla, cerebellum, spinal cord

45 The Brain Stem (cont.) Pons Connecting link between the cerebellum and rest of the nervous system Regulates some reflexes involving respiration

46 The Brain Stem (cont.) Medullary Oblongata Respiratory center Cardiac center Vasomotor center Contralateral (opposite side) control

47 The Brain Stem (cont.) Checkpoint 10-7 What are the three subdivisions of the brain stem?

48 The Brain Stem (cont.) Pop Quiz 10.4 Which part of the brain stem contains relay centers for eye and ear reflexes? A) Pons B) Thalamus C) Medulla oblongata D) Midbrain

49 The Brain Stem (cont.) Pop Quiz Answer 10.4 Which part of the brain stem contains relay centers for eye and ear reflexes? A) Pons B) Thalamus C) Medulla oblongata D) Midbrain

50 The Cerebellum Learning Objectives 8. Describe the cerebellum, and identify its functions. 9. Name three neuronal networks that involve multiple regions of the brain, and describe the function of each.

51 The Cerebellum (cont.) Three parts Vermis Left hemisphere Right hemisphere Functions Helps coordinate voluntary muscles Helps maintain balance Helps maintain muscle tone

52 The Cerebellum (cont.) Figure 10-7 The cerebellum.

53 The Cerebellum (cont.) Checkpoint 10-8 What are some functions of the cerebellum?

54 Widespread Neuronal Networks Limbic System Between the cerebrum and diencephalon Involved in emotional states, behavior Involved in learning, long-term memory Stimulates reticular formation (consciousness) Links functions of the cerebral cortex and brain stem Basal Nuclei Reticular Formation Reticular activating system (RAS)

55 Widespread Neuronal Networks (cont.) Figure 10-8 The limbic system. Which part of the cerebral cortex contributes to the limbic system?

56 The Cerebellum (cont.) Checkpoints 10-9 What are four structures in the limbic system? What is the function of the basal nuclei? What is the function of the reticular activating system?

57 The Cerebellum Pop Quiz 10.5 Which of the following is NOT a function of the cerebellum? A) Maintaining muscle tone B) Maintaining balance C) Coordinating voluntary muscles D) Initiating movements of voluntary muscles

58 The Cerebellum (cont.) Pop Quiz Answer 10.5 Which of the following is NOT a function of the cerebellum? A) Maintaining muscle tone B) Maintaining balance C) Coordinating voluntary muscles D) Initiating movements of voluntary muscles

59 Brain Studies Learning Objective 10.Describe four techniques used to study the brain.

60 Brain Studies (cont.) Brain Imaging Techniques Computed tomography (CT) scan Magnetic resonance imaging (MRI) Positron emission tomography (PET)

61 Brain Studies (cont.) Figure 10-9 Imaging the brain.

62 Brain Studies (cont.) Electroencephalography Record electric currents given off by brain nerve cells Used to Study sleep patterns Diagnose disease Locate tumors Study drug effects Determine brain death

63 Brain Studies (cont.) Figure Electroencephalography.

64 Disorders of the Brain and Associated Structures Learning Objective 11.Describe at least six disorders that affect the brain.

65 Disorders of the Brain and Associated Structures (cont.) Seizures and Epilepsies Seizure Epilepsy Inflammation Meningitis Inflammation of brain and spinal cord coverings Encephalitis Inflammation of the brain Hydrocephalus Abnormal CSF accumulation within the brain

66 Disorders of the Brain and Associated Structures (cont.) Figure Hydrocephalus.

67 Disorders of the Brain and Associated Structures (cont.) Stroke and Other Brain Disorders Stroke Most common brain disorder Tumors Gliomas

68 Disorders of the Brain and Associated Structures (cont.) Figure Brain tumor.

69 Disorders of the Brain and Associated Structures (cont.) Head Injury Head trauma can lead to injury within the skull. Hematomas Epidural Subdural Intracerebral Cerebral concussion

70 Disorders of the Brain and Associated Structures (cont.) Figure Hematomas. What type of hematoma forms outside of the dura mater? What type forms below the dura mater?

71 Disorders of the Brain and Associated Structures (cont.) Degenerative Diseases Alzheimer disease Multi-infarct dementia Parkinson disease Huntington disorder

72 Disorders of the Brain and Associated Structures (cont.) Figure Effects of Alzheimer disease.

73 Disorders of the Brain and Associated Structures (cont.) Checkpoints What is the common term for cerebrovascular accident (CVA)? What type of cells are commonly involved in brain tumors?

74 Disorders of the Brain and Associated Structures (cont.) Pop Quiz 10.6 Which of the following symptoms is suggestive of Alzheimer disease? A) Memory loss B) Tremor C) Impaired balance D) Limb rigidity

75 Disorders of the Brain and Associated Structures (cont.) Pop Quiz Answer 10.6 Which of the following symptoms is suggestive of Alzheimer disease? A) Memory loss B) Tremor C) Impaired balance D) Limb rigidity

76 Cranial Nerves Learning Objectives 12.List the names and functions of the 12 cranial nerves. 13.Discuss five disorders that involve the cranial nerves.

77 Cranial Nerves (cont.) 12 pairs Four categories: Special sensory impulses General sensory impulses Somatic motor impulses Visceral motor impulses

78 Cranial Nerves (cont.) Names and Functions of the Cranial Nerves Nerve Name Function I Olfactory Carries impulses for the sense of smell toward the brain II Optic Carries visual impulses from the eye to brain III Oculomotor Controls contraction of eye muscles IV Trochlear Supplies one eyeball muscle V Trigeminal Carries sensory impulses from eye, upper jaw, and lower jaw toward the brain VI Abducens Controls an eyeball muscle VII Facial Controls muscles of facial expression; carries sensation of taste; stimulates small salivary glands and lacrimal (tear) glands

79 Cranial Nerves (cont.) Names and Functions of the Cranial Nerves (cont.) Nerve Name Function VIII Vestibulocochlear Carries sensory impulses for hearing and equilibrium from inner ear toward the brain IX Glossopharyngeal Carries sensory impulses from tongue and pharynx (throat); controls swallowing muscles and stimulates the parotid salivary gland X Vagus Supplies most of organs in thoracic and abdominal cavities; carries motor impulses to the larynx (voice box) and pharynx XI Accessory Controls muscles in the neck and larynx XII Hypoglossal Controls muscles of tongue

80 Cranial Nerves (cont.) Figure Cranial nerves.

81 Disorders Involving the Cranial Nerves Destruction of optic fibers Damage to hearing nerves Paralysis of muscles Bell palsy Neuralgia

82 Cranial Nerves (cont.) Checkpoints How many pairs of cranial nerves are there? What are the three types of cranial nerves? What is a mixed nerve?

83 Cranial Nerves (cont.) Pop Quiz 10.7 Which cranial nerve is concerned with the sense of smell? A) Vagus nerve B) Trigeminal nerve C) Olfactory nerve D) Hypoglossal nerve

84 Cranial Nerves (cont.) Pop Quiz Answer 10.7 Which cranial nerve is concerned with the sense of smell? A) Vagus nerve B) Trigeminal nerve C) Olfactory nerve D) Hypoglossal nerve

85 Effects of Aging on the Nervous System Decreased brain size and weight Decreased speed of information processing Slowed movements Diminished memory Reduced blood flow to the brain

86 Case Study Learning Objective 14.Using information in the case study, list the possible effects of mild traumatic brain injury.

87 Case Study (cont.) Symptoms of a Concussion Headache Slurred speech Blurred vision Slow to arouse Nausea and vomiting Changes Cognitive Physical Emotional Behavioral Treatment Close observation of the injured person Quiet and rest Avoidance of overstimulation and alcohol Avoidance of using electronics

88 Word Anatomy Learning Objective 15.Show how word parts are used to build words related to the nervous system.

89 Word Anatomy (cont.) Word Part Meaning Example Protective Structures of the Brain and Spinal Cord cerebr/o brain Cerebrospinal fluid circulates around the brain and spinal cord. chori/o membrane The choroid plexus is the vascular membrane in the ventricle that produces CSF. contra- opposed, against The cerebral cortex has contralateral control of motor function. encephal/o brain The diencephalon is the part of the brain located between the cerebral hemispheres and the brain stem. gyr/o circle A gyrus is a circular raised area on the surface of the brain. latero lateral, side See contra- example.

90 Word Anatomy (cont.) Word Part Meaning Example Brain Studies tom/o cut Tomography is a method for viewing sections as if cut through the body. Disorders of the Brain and Associated Structures cephal/o head Hydrocephalus is the accumulation of fluid within the brain. -rhage bursting forth A cerebral hemorrhage is a sudden bursting forth of blood in the brain. phasia Cranial Nerves speech, ability to talk Aphasia is a loss or defect in language communication. gloss/o tongue The hypoglossal nerve controls muscles of the tongue.