Chapter 10: The Nervous System: The Brain and Cranial Nerves

Overview

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

Overview of the Brain Learning Outcomes Give the location of the four main divisions of the brain. Name and describe the three meninges. Cite the function of cerebrospinal fluid and describe where and how this fluid is formed.

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

Overview of the Brain Division Description Functions Brain stem Midbrain Pons Medulla oblongata Below anterior cerebrum Below cerebrum Anterior to cerebellum Above spinal cord Connects brain to spinal cord Contains visual and auditory reflex centers Regulates respiration Regulates respiration and heartbeat Cerebellum Below posterior cerebrum Divided into two hemispheres Coordinates voluntary muscles Maintains balance and muscle tone

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

Overview of the Brain Protective Structures of the Brain and Spinal Cord Meninges Dura mater Dural sinuses Arachnoid Pia mater

Figure 10-2 Frontal (coronal) section of the top of the head 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?

Overview of the Brain Protective Structures of the Brain and Spinal Cord 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

Overview of the Brain Protective Structures of the Brain and Spinal Cord Ventricles Four fluid-filled spaces within brain Lateral (2) Third Fourth Contain choroid plexus, which manufactures CSF Supports nervous tissue, cushions from shock Carries nutrients to cells Transports waste products from cells

Figure 10-3 Flow of CSF. Which ventricle is continuous with the central canal of the spinal cord? 12

Figure 10-4 Ventricles of the brain. Which are the largest ventricles?

✓ Overview of the Brain 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?

? Overview of the Brain Pop Quiz 10.1 Which division of the brain is physically connected to the spinal cord? Brain stem Cerebellum Cerebrum Diencephalon

? Overview of the Brain Pop Quiz Answer 10.1 Which division of the brain is physically connected to the spinal cord? Brain stem Cerebellum Cerebrum Diencephalon

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

The Cerebrum The Cerebral Hemispheres Cerebrum divided into two cerebral hemispheres Each hemisphere is divided into five lobes Frontal Parietal Temporal Occipital Insula (within the hemisphere)

The Cerebrum The Cerebral Hemispheres Outer layer of nervous tissue is called the cortex Cortex arranged into folds Gyri Sulci Central sulcus Lateral sulcus

The Cerebrum The Cerebral Hemispheres Internal layer composed mostly of white matter Corpus callosum bridges cerebral hemispheres Also contains scattered “islands” of gray matter Basal nuclei

Figure 10-5 External surface of the brain. What structure separates the frontal from the parietal lobe? The temporal lobe from the frontal and parietal lobes? 21

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

Figure 10-6 Functional areas of the cerebral cortex. What cortical area is posterior to the central sulcus? What area is anterior to the central sulcus? 23

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

The Cerebrum Memory and the Learning Process Limbic system Between cerebrum and diencephalon Involved in emotional states, behavior Involved in learning, long-term memory Stimulates reticular formation (consciousness) Links functions of cerebral cortex and brain stem

✓ The Cerebrum Checkpoints 10-4 What are the four surface lobes of each cerebral hemisphere? 10-5 What is the name of the thin outer layer of gray matter where higher brain functions occur? 26

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

? The Cerebrum 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 Temporal and frontal

The Diencephalon Learning Outcome Name two divisions of the diencephalon and cite the functions of each.

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

Figure 10-7 Regions of the diencephalon. To what part of the brain is the pituitary gland attached? 31

✓ The Diencephalon Checkpoint 10-6 What are the two main portions of the diencephalon and what do they do? 32

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

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

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

The Brain Stem Connects cerebrum and diencephalon with the spinal cord Composed of midbrain, pons, and medulla oblongata

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

The Brain Stem Pons Connecting link between cerebellum and rest of nervous system Regulates some reflexes involving respiration

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

Figure 10-8 The brain stem and cerebellum. 40

✓ The Brain Stem Checkpoint 10-7 What are the three subdivisions of the brain stem? 41

? The Brain Stem 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

? The Brain Stem 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

The Cerebellum Learning Outcome Describe the cerebellum and identify its functions.

The Cerebellum Three parts Vermis Left hemisphere Right hemisphere Functions Help coordinate voluntary muscles Help maintain balance Help maintain muscle tone

Figure 10-8 The brain stem and cerebellum. 46

✓ The Cerebellum Checkpoint 10-8 What are some functions of the cerebellum? 47

? 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 Initiating movements of voluntary muscles

? The Cerebellum 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 Initiating movements of voluntary muscles

Brain Studies Learning Outcome Describe four techniques used to study the brain.

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

Figure 10-9 Imaging the brain. 52

Brain Studies 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

Figure 10-10 Electroencephalography. 54

Cranial Nerves Learning Outcome List the names and functions of the 12 cranial nerves.

Cranial Nerves 12 pairs 4 categories Special sensory impulses General sensory impulses Somatic motor impulses Visceral motor impulses

Cranial Nerves Names and Functions of the Cranial Nerves Nerve Name Olfactory Carries impulses for the sense of smell toward brain II Optic Carries visual impulses from 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 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

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

Figure 10-15 Cranial nerves. 59

✓ Cranial Nerves Checkpoints 10-11 How many pairs of cranial nerves are there? 10-12 (a) What are the three types of cranial nerves? 10-12 (b) What is a mixed nerve? 60

? Cranial Nerves Pop Quiz 10-6 Which cranial nerve is concerned with the sense of smell? A) Vagus nerve B) Trigeminal nerve C) Olfactory nerve D) Hypoglossal nerve

? Cranial Nerves Pop Quiz Answer 10-6 Which cranial nerve is concerned with the sense of smell? A) Vagus nerve B) Trigeminal nerve C) Olfactory nerve D) Hypoglossal nerve

Disorders of the Brain and Associated Structures Learning Outcome Discuss several disorders that involve the brain, its associated structures, or the cranial nerves.

Disorders of the Brain and Associated Structures Inflammation Meningitis Inflammation of brain and spinal cord coverings Encephalitis Inflammation of brain Hydrocephalus Abnormal CSF accumulation within brain

Figure 10-11 Hydrocephalus. 65

Disorders of the Brain and Associated Structures Stroke and Other Brain Disorders Stroke Most common brain disorder Cerebral palsy Epilepsy Tumors Gliomas

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Figure 10-12 Brain tumor. 68

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

Figure 10-13 Hematomas. What type of hematoma forms outside of the dura mater? What type forms below the dura mater? 70

Disorders of the Brain and Associated Structures Degenerative Diseases Alzheimer disease Multi-infarct dementia Parkinson disease

Figure 10-14 Effects of Alzheimer disease. 72

Disorders of the Brain and Associated Structures Disorders Involving the Cranial Nerves Destruction of optic fibers Damage to hearing nerves Paralysis of muscles Bell palsy Neuralgia

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Disorders of the Brain and Associated Structures ✓ Disorders of the Brain and Associated Structures Checkpoints 10-9 What is the common term for cerebrovascular accident (CVA)? 10-10 What type of cells are commonly involved in brain tumors? 75

Disorders of the Brain and Associated Structures ? Disorders of the Brain and Associated Structures Pop Quiz 10-7 Which of the following symptoms is suggestive of Alzheimer disease? A) Memory loss B) Tremor C) Impaired balance D) Limb rigidity

Disorders of the Brain and Associated Structures ? Disorders of the Brain and Associated Structures Pop Quiz Answer 10-7 Which of the following symptoms is suggestive of Alzheimer disease? A) Memory loss B) Tremor C) Impaired balance D) Limb rigidity

Effects of Aging on the Nervous System

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 brain

Case Study Learning Outcomes Match some of the patient’s signs and symptoms in the case study to the parts of his brain that were damaged by the stroke. 80

Case Study Sign or Symptom Damaged Part of Brain Right limb hemiplegia Primary motor area of left frontal lobe Right-sided diminished sense of touch Primary sensory area of left parietal lobe

Word Anatomy Learning Outcome Show how word parts are used to build words related to the nervous system. 82

Word Anatomy Word Part Meaning Example 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. encephal/o The diencephalon is the part of the brain located between the cerebral hemispheres and the brain stem. cephal/o head Hydrocephalus is the accumulation of fluid within the brain. phasia speech, ability to talk Aphasia is a loss or defect in language communication. gloss/o tongue The hypoglossal nerve controls muscles of the tongue.

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