Download LEARNING OBJECTIVE 7: Explain hemisphere dominance.

CHAPTER 11
NERVOUS SYSTEM II: DIVISIONS OF THE NERVOUS
SYSTEM
LEARNING OBJECTIVE 1: Describe the coverings of the brain and spinal cord.
Lecture Suggestions and Guidelines
1. Discuss the dura mater, the tough outermost meningeal layer; the arachnoid mater, the threadlike, middle
meningeal layer; and the pia mater, the delicate, innermost meningeal layer.
2. Lecture on meningitis and encephalitis.
3. Briefly discuss the blood-brain barrier.
4. Describe the partitions of the dura mater.
Application Question(s)
1. Ask students to develop a flow chart depicting the location of formation, circulation, and reabsorption of CSF.
Begin with a box labeled choroid plexuses of the lateral and third ventricle.
Answer: CSF is formed from blood plasma in the lateral and third ventricle, which then flows through the
fourth ventricle, to the central canal of the spinal cord, to the cranial and subarachnoid spaces, reabsorbed
through arachnoid villi into cranial venous sinuses, where the CSF becomes plasma once again.
Critical Thinking Issue(s)
1. Meningitis is an acute inflamation of the meninges. Which meninges are most likely affected and what are some
possible causes?
Answer: Meningitis most often affects the pia mater and arachnoid mater. It can be bacterial or viral in nature.
Bacterial meningitis may be caused by an infection of the middle ear, upper respiratory tract, frontal sinus
infection, or carried through the blood from the lung. Viral meningitis is commonly caused by mumps, polio
viruses, and occasionally from herpes simplex.
LEARNING OBJECTIVE 2: Describe the structure of the spinal cord and its major functions.
and
LEARNING OBJECTIVE 3: Describe a reflex arc.
and
LEARNING OBJECTIVE 4: Define reflex behavior.
Lecture Suggestions and Guidelines
1. Give a brief overview of the spinal cord structure. Describe the thirty-one segments, the neck region, the two
major grooves, the gray commissure, and the funiculi.
2. Describe the spinal cord’s two major functions: a) a conduit for sensory impulses; and b) a center for spinal
reflexes.
3. Introduce the major ascending tracts, including fasciculus gracilis/cuneatus, spinothalamic tracts, and
spinocerebellar tracts.
4. Introduce the major descending tracts, including corticospinal tracts, reticulospinal tracts, and rubrospinal
tracts.
5. Describe a reflex arc and explain how nerve impulses follow nerve pathways as they travel through the nervous
system.
6. Discuss various reflex behaviors.
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Application Question(s)
1. Ask students to prepare a brief report on spina bifida.
Answer: Spina bifida is a condition in which one or more of the vertebrae fail to fuse; leaving an opening in
the vertebral column. It may not be apparent at birth, but later manifestations include hydrocephalus, cleft
palate, club foot, strabismus, and muscular abnormalities.
Critical Thinking Issue(s)
1. Compare three abnormal conditions in the developmental aspect of the spinal column known as meningocele,
meningomyelocele, and myelocele. Which of the three appears to be most tragic?
Answer: In meningocele, the meninges protrude through an opening in the vertebrae as a sac filled with CSF.
The spinal cord is not involved. Meningomyelocele patients exhibit protruding nerve elements which are
trapped and cannot reach their destination. It is more serious than meningocele, but surgery is successful in a
significant number of cases. Myelocele, the most serious form, is a condition in which the neural tube fails to
close resulting in disorganized nerve tissue. This condition is usually fatal.
LEARNING OBJECTIVE 5: Name the major parts of the brain and describe the functions of each.
Lecture Suggestions and Guidelines
1. Discuss the structural development of the brain.
2. Describe the structure and function of the cerebrum. Include the frontal lobe, parietal lobe, temporal lobe,
occipital lobe, insula, and cerebral cortex.
3. Introduce the concepts of hemisphere dominance and memory.
4. Describe the basal ganglia.
5. Describe the ventricles and cerebrospinal fluid.
6. Discuss the structures and functions of the diencephalon.
7. Describe the brain stem, including the midbrain, pons, and medulla oblongata.
8. Discuss the structure and function of the cerebellum.
Application Question(s)
1. Provide a model of the human brain and ask students to identify the major structures, lobes, and sensory areas.
Repetition is the key. Reinforce applied knowledge with commercially available animal specimens.
Answer: N/A
Critical Thinking Issue(s)
1. Surgical severing of the corpus callosum has been used to correct miscommunication problems between the
right and left cerebral hemispheres. How is this effective?
Answer: The dominant hemisphere and nondominant hemisphere are capable of communication with one
another via the nerve fibers of the corpus callosum which connect the two hemispheres. In a recent experiment,
a patient was shown a picture of a woman talking on the telephone. When the patient attempted to write down
what she saw, her written words described something totally unrelated to the picture. By severing the corpus
callosum, the dominant and nondominant hemispheres of the brain were allowed to function "independently" of
each other, enabling interpretation and the motor cortex to function.
LEARNING OBJECTIVE 6: Distinguish among motor, sensory, and association areas of the cerebral
contex.
Lecture Suggestions and Guidelines
1. Give an overview of the functional regions of the cortex.
2. Lecture on the primary motor areas. Include a discussion of the pyramidal cells, Broca’s area and the frontal
eye field.
3. Discuss the sensory areas involved with the sensations of temperature, touch, pressure, and pain, and the senses
of vision, hearing, taste, and smell.
4. Describe the association areas involved with memory, reasoning, planning, etc.
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Application Question(s)
1. Stroke victims are sometimes frustrated during recovery because they know what they want to say, but cannot
vocalize the words. What has most likely happened?
Answer: Broca's area, which is usually located in the left cerebral hemisphere, has most likely been damaged.
Critical Thinking Issue(s)
1. Two defective genes are under investigation in the study of Alzheimer’s disease. A defective gene on
chromosome 19 is being researched, having been found in a significant number of late-onset cases. Also, a
defective gene on chromosome 21, which produces a protein called beta-amyloid, is of significance in earlyonset cases. Is there a connection between Alzheimer’s disease and Down’s syndrome, a disease in which the
patient maintains an extra chromosome in the 21st position?
Answer: Current research has revealed that a vast majority of Down's syndrome patients of at least 45 years of
age also develop Alzheimer's disease.
LEARNING OBJECTIVE 7: Explain hemisphere dominance.
Lecture Suggestions and Guidelines
1. Give an overview of dominant and nondominant hemispheres.
2. Define the corpus callosum and relate it to the concept of hemisphere dominance.
3. Distinguish between memory and learning.
Application Question(s)
1. What is the relationship between being left-handed/right-handed and left hemisphere/right hemisphere
dominance?
Answer: The left hemisphere is dominant in 90% of right-handed adults. The left hemisphere is dominant in
64% of left-handed adults. The right hemisphere is dominant in 10% of right-handed adults. The right
hemisphere is dominant in 16% of left-handed adults. 16% of left-handed adults have hemispheres that are
equally dominant.
Critical Thinking Issue(s)
1. Does the region in the nondominant hemisphere that corresponds to Broca’s area also control speech?
Answer: No, it influences the emotional aspects of the language expressed in speech.
LEARNING OBJECTIVE 8: Explain the stages in memory storage.
Lecture Suggestions and Guidelines
1. Discuss the process of consolidation.
2. Distinguish between long-term and short-term memory processes.
3. Introduce the theory of long-term synaptic potentiation.
Application Question(s)
1. Ask students to recall events stored in their long-term memory. What is the earliest event they can remember in
detail? Does anyone remember being born?
Answer: Responses will vary.
Critical Thinking Issue(s)
1. Ask students to prepare a brief report on recent findings regarding consolidation, the process by which shortterm memories are converted to long-term memories.
Answer: N/A
LEARNING OBJECTIVE 9: Describe the formation and function of cerebrospinal fluid.
Lecture Suggestions and Guidelines
1. Discuss the series of interconnected cavities called ventricles.
2. Describe the role of choroid plexuses in the secretion of cerebrospinal fluid.
3. Discuss the pattern of cerebrospinal fluid circulation.
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Application Question(s)
1. Provide a diagram of the human brain to students and ask them to trace the flow of cerebrospinal fluid from the
two lateral ventricles to its return to the blood in the dural sinuses.
Answer: N/A
Critical Thinking Issue(s)
1. Why is it important that a patient remain in a horizontal position following a spinal tap procedure?
Answer: The cerebrospinal fluid pressure is decreased following this procedure. It is recommended that the
patient remain in a horizontal resting position for a period of six to twelve hours after the procedure. This
precaution will prevent spinal headaches.
LEARNING OBJECTIVE 10: Explain the functions of the limbic system and the reticular formation.
Lecture Suggestions and Guidelines
1.
2.
3.
4.
Discuss ways in which the limbic system influences a person’s behavior.
Describe the location and function of the reticular formation.
Introduce the terms REM and non-REM.
Describe two types of normal sleep.
Application Question(s)
1. Explain why you can “smell” freshly baked bread simply by being reminded of the experience from your past
even though you haven’t recently visited a bakery.
Answer: Portions of the limbic system interpret sensory impulses from olfactory receptors. The limbic system
controls emotional experience and expression, and olfactory sensations may be long-lasting. Ask students to
give other examples of this phenomenon.
Critical Thinking Issue(s)
1. Compare the events which occur during REM and non-REM sleep.
Answer: During REM sleep, some areas of the brain are still active. The eyes rapidly move beneath the
eyelids. REM sleep lasts for 5-15 minutes. Heart and respiratory rates are irregular. Dreams take place.
Non-REM sleep ranges from light to heavy, lasts from 70-90 minutes, is restful, dreamless, and occurs when a
person is very tired. Non-REM sleep is accompanied by lowered blood pressure.
LEARNING OBJECTIVE 11: List the major parts of the peripheral nervous system.
Lecture Suggestions and Guidelines
1. Give an overview of the subdivisions of the peripheral nervous system, including the cranial nerves arising
from the brain and the spinal nerves arising from the spinal cord.
2. Briefly describe the somatic nervous system.
3. Briefly describe the autonomic nervous system.
Application Question(s)
1. For each of the twelve pairs of cranial nerves, what simple, but effective, clinical test could be used to insure
normal function?
Answer: Examples of responses: a) To test the olfactory nerves (cranial nerve pair I), he patient could be asked
to identify certain odors, such as ammonia, oranges, or vanilla; b) To test the vestibulocochlear nerves (cranial
nerve pair VIII), the patient would respond to a tuning fork.
Critical Thinking Issue(s)
1. Compare and contrast the somatic and autonomic nervous systems.
Answer: Responses should include a discussion of the effector organs, the types of neurotransmitters utilized,
and the construction of their efferent pathways.
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LEARNING OBJECTIVE 12: Describe the structure of a peripheral nerve and how its fibers are
classified.
Lecture Suggestions and Guidelines
1. Although this material was introduced in Chapter 10, reiterate the general structure of a peripheral nerve.
2. Confirm the students’ understanding of the structure of a peripheral nerve by asking them to draw and label the
major parts of a peripheral nerve.
3. Define epineurium, perineurium, and endoneurium.
Application Question(s)
1. Provide students with a diagram of a peripheral mixed nerve and ask them to label the major structures.
Answer: The diagram should include the fascicle, epineurium, perineurium, endoneurium, Schwann cell, axon,
motor ending, neurilemma, Node of Ranvier, and myelin sheath.
Critical Thinking Issue(s)
1. Ask the students to prepare a brief report on trigeminal neuralgia, a disorder of the trigeminal nerve.
Answer: The report should include causes, signs/symptoms, etiology, treatment, and prognosis.
LEARNING OBJECTIVE 13: Name the cranial nerves and list their major functions.
Lecture Suggestions and Guidelines
1. Describe the twelve pairs of cranial nerves. Include the Roman numeral identification, name, type, origin,
course, and function.
2. Provide the students with an illustration depicting an inferior view of the brain and brain stem which they can
label with each of the twelve cranial nerve pairs.
3. Ask students to devise a unique saying or slogan which employs an acronym formed by the first letter of each
of the twelve pairs of cranial nerves as an aid to learning the names and correct order.
Application Question(s)
1. Ask students to develop a set of twelve index cards, each of which contains the name, number, type, and
function for each of the twelve pairs of cranial nerves.
Again, repetition is the key. Quiz the students daily on the information written on the index cards.
Answer: N/A
Critical Thinking Issue(s)
1. If a patient presented difficulty in rotating his head or shrugging his shoulders against resistance, which pair of
cranial nerves would most likely be investigated?
Answer: The Accessory nerves (cranial nerve pair XI), activate the sternocleidomastoid and trapezius muscles.
LEARNING OBJECTIVE 14: Explain how spinal nerves are named and their functions.
Lecture Suggestions and Guidelines
1. Discuss the concept that spinal nerves are not named individually, but are grouped by the level from which they
arise.
2. Describe dorsal and ventral rami.
3. Introduce the term plexus.
4. Discuss the 31 pairs of spinal nerves in terms of the plexus with which they are associated, origins, the function
of the important nerves within each plexus, and the location of the body which the plexus serves.
Application Question(s)
1. Ask students to trace which body areas are served by the cervical plexus; brachial plexus; lumbar plexus; sacral
plexus.
Answer: Direct the students’ responses by offering the following guidelines: cervical plexus contains the
phrenic nerve; brachial plexus contains the axillary, radial, median, musculocutaneous, and ulnar nerves;
lumbar plexus contains the femoral and obturator nerves; sacral plexus contains the sciatic, common peroneal,
and tibial nerves.
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Critical Thinking Issue(s)
1. Ask students to determine possible results of damage to the above-mentioned nerves. Use previously learned
body movement nomenclature, whenever possible, e.g., adduction, extension, plantar flexion, etc.
Answer: Responses will vary.
LEARNING OBJECTIVE 15: Describe the general characteristics of the autonomic nervous system.
and
LEARNING OBJECTIVE 16: Distinguish between the sympathetic and the parasympathetic divisions
of the autonomic nervous system.
and
LEARNING OBJECTIVE 17: Describe a sympathetic and a parasympathetic nerve pathway.
and
LEARNING OBJECTIVE 18: Explain how the autonomic neurotransmitters differently affect visceral
effectors.
Lecture Suggestions and Guidelines
1. Discuss how autonomic functions are controlled in the hypothalamus, brain stem, and spinal cord.
2. Describe the integrative function of ganglia.
3. Introduce the two major subdivisions of the autonomic nervous system-sympathetic and parasympathetic.
Compare the anatomy of the subdivisions and briefly describe the sympathetic and parasympathetic effects on a
variety of organs and organ systems.
4. Lecture on control of autonomic activity by the CNS, medulla oblongata, hypothalamus, limbic system, and
cerebral cortex.
5. Introduce the terms cholinergic and adrenergic.
Application Question(s)
1. Compare the anatomy of the sympathetic and parasympathetic divisions of the autonomic nervous system.
Answer: Sympathetic division: a) First neurons are in the gray matter of the spinal cord; b) sympathetic chain
found on each side of the vertebral column; c) Second neurons found in collateral ganglion; and d)
postganglionic axon travels to visceral organ.
Parasympathetic division: a) First neurons located in the brain nuclei of cranial nerves and in the sacral region
of spinal cord; b) Second motor neuron found in terminal ganglion; and c) postganglionic axon travels to the
organ served.
Critical Thinking Issue(s)
1. Compare the effects on various organs during a sympathetic response with the effects during a parasympathetic
response.
Answer: The responses may be summarized in a table to include the following organs: heart, bronchioles, liver,
salivary glands, adrenal glands, stomach, intestines, urinary bladder, sweat glands, blood vessels, iris, and
ciliary muscles of the eye.
RELATED DISEASES OF HOMEOSTATIC INSTABILITY
1. Poliomyelitis—Polio in an infectious disease of the brain and spinal cord caused by a virus, usually affecting
children. Motor neurons are affected; muscles become paralyzed.
2. Tetanus—Commonly referred to as “lockjaw,” it is an infection of nerve tissue. The tetanus bacillus usually
enters the body through a wound. Muscles become rigid; painful spasms and convulsions may develop.
Immediate immunization to inactivate the toxin before it reaches the spinal cord is paramount.
3. Rabies—An infectious disease of the brain and spinal cord caused by a virus that is transmitted by the saliva of
an infected animal. Causes acute encephalomyelitis. Incubation period between 40–60 days.
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SUGGESTIONS FOR ADDITIONAL READING
Angell, Marcia. May 26, 1994. After Quinlan: The dilemma of the persistent vegetative state. New England Journal
of Medicine, vol. 330. Karen Quinlan spent nine years in a persistent vegetative state. Brain analysis reveals that
the causative defect was in Quinlan’s thalamus.
Changeux, Jean-Pierre. November 1993. Chemical signaling in the brain. Scientific American. Studies of
acetylcholine receptors in the electric organs of fish have generated critical insights into how neurons in the
human brain communicate with one another.
Damasio, Hanna, et al. May 20, 1994. The return of Phineas Gage: Clues about the brain from the skull of a famous
patient. Science, vol 264. In 1848, young Phineas Gage suffered a brain injury in a freak accident. His only
injuries were personality changes but they have revealed much about the function of the cerebral cortex.
Martin, Joseph. October 29, 1993. Molecular genetics of neurological diseases. Science, vol. 262. Abnormal
behavior, disturbing feelings, impaired reasoning ability, loss of coordination, and many other nervous system
dysfunctions can now be explained at the molecular level.
Olesen, J. December 22, 1994. Understanding the biologic basis of migrane. New England Journal of Medicine, vol.
331. These debilitating headaches can be helped if we know what causes them.
Posner, Michael I. October 29, 1993. Seeing the mind. Science, vol. 262. A combination of scanning technologies
allows us to observe brain structure and function.
Reiderer, Peter, and Moussa B. H. Youdim. January 1997. Understanding Parkinson’s Disease. Scientific American.
Skinner, Karen J. October 7, 1991. The chemistry of learning and memory. Chemical & Engineering News.
Researchers are unraveling the chemistry behind learning and memory.
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