1. CHAPTER 8
Nervous System

2. Nervous System Overview
Brain
Spinal cord
Nerves
Functions of nervous system
Regulates and coordinates all body activities
Center of all mental activity, including thought, learning, and memory

3. Nervous System Divisions
Central Nervous System (CNS)
Brain
Spinal Cord
Processes and stores sensory and motor information
Controls consciousness

4. Nervous System Divisions
Peripheral Nervous System (PNS)
12 Pairs of Cranial Nerves
31 Pairs of Spinal Nerves
Transmits sensory and motor impulses back and forth between CNS and rest of body

5. Nervous System Divisions

6. Peripheral Nervous System
Afferent (sensory) nerves
Carry impulses from the body to the central nervous system
Efferent (motor) nerves
Carry impulses from the central nervous system to muscles and glands
Cause the target organs to do something in response to commands

7. Peripheral Nervous System
Somatic Nervous System (SNS)
Provides voluntary control over skeletal muscle contractions
Autonomic Nervous System (ANS)
Provides involuntary control over smooth muscle, cardiac muscle, and glandular activity and secretions in response to the commands of the central nervous system

8. Autonomic Nervous System
Sympathetic nerves
Increase heart rate
Constrict blood vessels
Raise blood pressure
Fight-or-flight response
Parasympathetic nerves
Slow heart rate
Increase peristalsis of intestines
Increase glandular secretions
Relax sphincters

9. Cells of the Nervous System
Neuron
Cell body
Contains the nucleus and cytoplasm
Axon
Conducts impulses away from the cell body
Some axons are covered with a myelin sheath
Dendrite
Conducts impulses toward the cell body
Synapse
Space between two nerves which the impulse must cross

10. Cells of the Nervous System

11. Cells of the Nervous System
Neuroglia
Connective tissue
Support system for neurons
Do not conduct impulses
Protect nervous system through phagocytosis
Types of Neuroglia Cells
Astrocytes
Microglia
Oligodendrocytes

12. Central Nervous System
Brain
Surrounded by bone for protection
Enclosed in cranium
Spinal cord
Surrounded by vertebrae for protection
Surrounded by meninges and cerebrospinal fluid

13. Meninges Dura mater Outermost layer of meninges
Tough, white connective tissue
Epidural space
Located outside of the dura mater
Contains supporting cushion of fat and connective tissue
Subdural space
Located beneath the dura mater
Cavity is filled with serous fluid

14. Meninges Arachnoid membrane Pia mater Middle layer of the meninges
Resembles a spider web
Subarachnoid space immediately beneath
Contains cerebrospinal fluid
Pia mater
Innermost layer of the meninges
Tightly bound to the surface of the brain and spinal cord

15. Structures of the Brain
Cerebrum
Largest and uppermost portion of the brain
Controls consciousness, memory, sensations, emotions, voluntary movements
Cortex = outer surface
Gyri = elevations
Sulci = grooves
Longitudinal fissure divides cerebrum into two hemispheres

16. Structures of the Brain
Cerebellum
Attached to the brain stem
Maintains muscle tone
Coordinates normal movement and balance
Diencephalon
Located between cerebrum and midbrain
Consists of thalamus, hypothalamus, and pineal gland

17. Structures of the Brain
Brain Stem
Region between diencephalon and spinal cord
Consists of midbrain, pons, and medulla oblongata
Serves as pathway for impulses between brain and spinal cord
Controls respiration, blood pressure, and heart rate

18. Spinal Cord Pathway for impulses traveling to and from brain
Carries 31 pairs of spinal nerves
Affects limbs and lower part of body

19. PATHOLOGICAL CONDITIONS
Nervous System

20. Alzheimer’s Disease Pronounced Defined (ALTS-high-merz dih-ZEEZ)
Progressive and extremely debilitating deterioration of a person’s intellectual functioning

21. Amyotrophic Lateral Sclerosis (ALS)
Pronounced
(ah-my-oh-TROFF-ik LAT-er-al skleh-ROH-sis)
Defined
Severe weakening and wasting of the involved muscle groups
Usually begins with hands
Progresses to shoulders, upper arms, then legs

22. Anencephaly Pronounced Defined (an-en-SEFF-ah-lee)
Absence of the brain and spinal cord at birth
Condition is incompatible with life

23. Bell’s Palsy Pronounced Defined (BELLZ PAWL-zee)
Temporary or permanent unilateral weakness or paralysis of muscles in the face

24. Brain Abscess Pronounced Defined (BRAIN AB-sess)
Accumulation of pus located anywhere in the brain tissue

25. Carpal Tunnel Syndrome
Pronounced
(CAR-pal TUN-el SIN-drom)
Defined
Pinching or compression of median nerve within the carpal tunnel
Inflammation and swelling of tendons cause intermittent or continuous pain

26. Cerebral Concussion Pronounced Defined (seh-REE-bral con-KUSH-un)
Brief interruption of brain function usually with loss of consciousness lasting for a few seconds

27. Cerebral Contusion Pronounced Defined (seh-REE-bral con-TOO-zhun)
Small, scattered venous hemorrhages in the brain
Bruise of the brain tissue
Occurs when brain strikes the inner skull

28. Cerebral Palsy Pronounced Defined (seh-REE-bral PAWL-zee)
Collective term used to describe congenital brain damage that is permanent but not progressive
Characterized by the child’s lack of control of voluntary muscles

29. Cerebral Palsy Spastic Ataxic Damage to cortex of the brain
Tense muscles
Very irritable muscle tone
Ataxic
Damage to cerebellum
Affects equilibrium

30. Cerebral Palsy Athetoid Rigidity Mixed cerebral palsy
Damage to basal ganglia
Causes sudden jerking
Rigidity
Causes child to be in continual state of tension
Mixed cerebral palsy

31. Cerebrovascular Accident (CVA)
Pronounced
(seh-REE-broh-VASS-kyoo-lar AK-sih-dent)
Defined
Death of a specific portion of brain tissue
Results from decreased blood flow to that area of the brain
Also called a stroke

32. Cerebrovascular Accident
Causes
Transient ischemic attacks (TIAs)
Also known as mini strokes
Cerebral thrombosis
Occurs largely in individuals older than 50
Cerebral embolism
Embolus causes an occlusion
Cerebral hemorrhage
Cerebral vessel ruptures

33. Degenerative Disk Pronounced Defined (deh-JEN-er-ah-tiv disk)
Deterioration of the intervertebral disk
Usually due to constant motion and wear on the disk

34. Encephalitis Pronounced Defined (En-seff-ah-LYE-tis)
Inflammation of the brain or spinal cord tissue
Virus enters CNS when person experiences viral disease such as mumps, measles, or through tick or mosquito bite

35. Epilepsy Pronounced Defined (EP-ih-lep-see)
Syndrome of recurring episodes of excessive irregular electrical activity of the central nervous system, called seizures

36. Grand Mal Seizure Pronounced Defined (grand MALL SEE-zyoor)
Epileptic seizure characterized by sudden loss of consciousness and generalized involuntary muscular contraction
Vacillates between rigid body extension and an alternating contracting and relaxing of muscles

37. Petit Mal Seizure Pronounced Defined (pet-EE MALL SEE-zyoor)
Small seizures in which there is a sudden, temporary loss of consciousness
Lasts only a few seconds
Also known as absence seizures

38. Guillain-Bàrré Syndrome
Pronounced
(GEE-yon bah-RAY SIN-drom)
Defined
Acute polyneuritis of the peripheral nervous system
Myelin sheaths on the axons are destroyed
Decreased nerve impulses
Loss of reflex response
Sudden muscle weakness
Usually follows viral gastrointestinal or respiratory infection

39. Headache (Cephalalgia)
Pronounced
(seff-ah-LAL-jee-ah)
Defined
Pain anywhere within the cranial cavity varying in intensity from mild to severe
May be chronic or acute
May occur as result of a disease process
May be totally benign

40. Migraine Headache Pronounced Defined (MY-grain headache)
Recurring, pulsating, vascular headache developing on one side of the head
Characterized by slow onset
May be preceded by an aura during which sensory disturbance occurs

41. Cluster Headache Pronounced Defined (KLUSS-ter headache)
Headache occurring typically two to three hours after falling asleep
Described as extreme pain around one eye that wakens the person from sleep

42. Tension Headache Pronounced Defined (TEN-shun headache)
Headache that occurs from long, endured contraction of the skeletal muscles around the face, scalp, upper back, and neck

43. Epidural Hematoma Pronounced Defined (eh-pih-DOO-ral hee-mah-TOH-mah)
Collection of blood located above the dura mater and just below the skull

44. Subdural Hematoma Pronounced Defined (sub-DOO-ral hee-mah-TOH-mah)
Collection of blood below the dura mater and above the arachnoid layer of the meninges

45. Herniated Disk Pronounced Defined (HER-nee-ay-ted disk)
Rupture or herniation of the disk center through the disk wall and into the spinal canal
Causes pressure on the spinal cord or nerve roots

46. Huntington’s Chorea Pronounced Defined (HUNT-ing-tonz koh-REE-ah)
Inherited neurological disease characterized by rapid, jerky, involuntary movements and increased dementia
Progressive, degenerative disease

47. Hydrocephalus Pronounced Defined (high-droh-SEFF-ah-lus)
Abnormal increase of cerebrospinal fluid in the brain that causes the ventricles of the brain to dilate
Results in increased head circumference in infant with open fontanel
Congenital disorder

48. Intracranial Tumors Pronounced Defined (in-trah-KRAY-nee-al TOO-morz)
Tumors occurring in any structural region of the brain
May be malignant or benign
Classified as primary or secondary
Named according to the tissue from which they originate

49. Primary Intracranial Tumors
Pronounced
(PRIGH-mah-ree in-trah-KRAY-nee-al TOO-morz)
Defined
Tumors that arise from gliomas and the meninges
Gliomas = malignant glial cells that are a support for nerve tissue

50. Primary Intracranial Tumors
Glioblastoma multiforme
Most rapidly growing of the gliomas
Astrocytomas
Tend to invade surrounding structures
Ependymomas
Occur more commonly in children and adolescents
Usually encapsulated and benign

51. Metastatic Intracranial Tumors (Secondary)
Pronounced
(met-ah-STAT-ik in-trah-KRAY-nee-al TOO-morz)
Defined
Tumors occurring as a result of metastasis from a primary site such as the lung or breast

52. Meningitis (Acute Bacterial)
Pronounced
(men-in-JYE-tis ah-KYOOT back-TEE-ree-al)
Defined
Serious bacterial infection of the meninges
Can have residual debilitating effects or even a fatal outcome
Must be diagnosed and treated promptly with appropriate antibiotic therapy

53. Multiple Sclerosis (MS)
Pronounced
(MULL-tih-pl SKLEH-roh-sis)
Defined
Degenerative inflammatory disease of the central nervous system attacking the myelin sheath in the spinal cord and brain
Leaves area sclerosed (hardened) or scarred

54. Myasthenia Gravis Pronounced Defined (my-ass-THEE-nee-ah GRAV-is)
Chronic progressive neuromuscular disorder
Causes skeletal muscle weakness (without atrophy) and fatigue
Occurring at different levels of severity

55. Narcolepsy Pronounced Defined (NAR-coh-lep-see)
Rare syndrome of uncontrolled, sudden attacks of sleep
Main features of narcolepsy are daytime sleepiness and cataplexy
Sudden loss of muscle tone

56. Neuroblastoma Pronounced Defined (noo-roh-blass-TOH-mah)
Highly malignant tumor of the sympathetic nervous system
Most commonly occurs in the adrenal medulla with early metastasis to liver, lungs, lymph nodes, and bone

57. Parkinson’s Disease Pronounced Defined (PARK-in-sons dih-ZEEZ)
Degenerative, slowly progressive deterioration of nerves in the brain stem’s motor system, characterized by a gradual onset of symptoms
Classic Symptoms: stooped posture with body flexed forward, bowed head, shuffling gait, pill-rolling gestures, expressionless mask-like facial appearance

58. Peripheral Neuritis Pronounced Defined (per-IF-er-al noo-RYE-tis)
Inflammation of one or more peripheral nerves
Effects are dependent upon particular nerve involved

59. Poliomyelitis Pronounced Defined (poh-lee-oh-my-ell-EYE-tis)
Infectious viral disease that affects the ability of spinal cord and brain motor neurons to receive stimulation
Virus enters through the upper respiratory tract
Muscles affected become paralyzed without the motor nerve stimulation

60. Post Polio Syndrome Pronounced Defined (POST POH-lee-oh SIN-drom)
Progressive weakness occurring at least 30 years after the initial poliomyelitis attack

61. Reye’s Syndrome Pronounced Defined (RISE SIN-drom)
Acute brain encephalopathy along with fatty infiltration of the internal organs that may follow acute viral infections
Occurs in children under the age of 18; often with a fatal result
Linked to aspirin administration during a viral illness

62. Shingles (Herpes Zoster)
Pronounced
(SHING-lz) (HER-peez ZOSS-ter)
Defined
Acute viral infection characterized by inflammation of the underlying spinal or cranial nerve pathway producing painful, vesicular eruptions on the skin along these nerve pathways
Seen mainly in adults

63. Shingles Image courtesy of Robert A. Silverman,
M.D., Pediatric Dermatology,
Georgetown University

64. Skull Fracture (Depressed)
Pronounced
(SKULL FRAK-chur, deh-PREST)
Defined
Broken segment of the skull bone thrust into the brain as a result of a direct force, usually a blunt object

65. Spina Bifida Cystica Pronounced Defined
(SPY-nah BIFF-ih-dah SISS-tih-kah)
Defined
Back portion of one or more vertebrae is not closed normally and a cyst protrudes through the opening in the back, usually at the level of the 5th lumbar or 1st sacral vertebrae
Congenital defect of the CNS

66. Meningocele Pronounced Defined (men-IN-goh-seel)
Cystlike sac covered with skin or a thin membrane protruding through the bony defect in the vertebrae containing meninges and CSF

67. Meningomyelocele Pronounced Defined (men-in-goh-my-ELL-oh-seel)
Cystlike sac covered with skin or a thin membrane protruding through the bony defect in the vertebrae that contains meninges, CSF, and spinal cord segments

68. Spina Bifida Occulta Pronounced Defined
(SPY-nah BIFF-ih-dah oh-KULL-tah)
Defined
Congenital defect of the central nervous system in which the back portion of one or more vertebrae is not closed
A dimpling over the area may occur

69. Paraplegia Pronounced Defined (pair-ah-PLEE-jee-ah)
Paralysis of the lower extremities caused by severe injury to the spinal cord in the thoracic or lumbar region
Results in loss of sensory and motor control below the level of the injury

70. Quadriplegia Pronounced Defined (kwod-rih-PLEE-jee-ah)
Paralysis of the trunk, legs, and pelvic organs with partial or total paralysis in the upper extremities caused by severe injury to the spinal cord between the 5th and 8th cervical vertebrae
The higher the trauma, the more debilitating the motor and sensory impairments

71. Tay-Sachs Disease Pronounced Defined (TAY SACKS dih-ZEEZ)
Congenital disorder caused by altered lipid metabolism, resulting from an enzyme deficiency
Accumulation of this type of lipid occurs in the brain, leading to progressive neurological deterioration with both physical and mental retardation

72. Trigeminal Neuralgia (Tic Douloureux)
Pronounced
(try-JEM-ih-nal noo-RAL-jee-ah),
(tik DOO-loh-roo)
Defined
Short periods of severe unilateral pain which radiates along the fifth cranial nerve (trigeminal nerve)
Heat, chewing, or touching of the affected area activates the pain

73. DIAGNOSTIC TECHNIQUES, TREATMENTS, AND PROCEDURES
Nervous System

74. Diagnostic Techniques, Treatments, and Procedures
Babinski’s Reflex
Reflex tested by stroking the sole of the foot, beginning at mid-heel and moving upward and lateral to the toes.
Positive Babinski’s occurs when there is dorsiflexion of the great toe and fanning of the other toes

75. Diagnostic Techniques, Treatments, and Procedures
Brain scan
Nuclear counter scanning of cranial contents two hours after an intravenous injection of radioisotopes
Isotopes concentrate in abnormal tissue of brain, indicating a pathological process

76. Diagnostic Techniques, Treatments, and Procedures
Cerebral Angiography
Visualization of the cerebral vascular system via x-ray after injection of a radiopaque contrast medium into an arterial blood vessel
May use carotid, femoral, or brachial artery

77. Diagnostic Techniques, Treatments, and Procedures
Cerebrospinal fluid analysis
Laboratory analysis of cerebrospinal fluid
Obtained from a lumbar puncture for the presence of bacteria, blood, malignant cells, and amount of protein and glucose present

78. Diagnostic Techniques, Treatments, and Procedures
CT scan of the brain
Analysis of a three-dimensional view of brain tissue obtained as X-ray beams pass through successive horizontal layers of the brain
CT = computerized tomography
Images look down through the top of the head

79. Diagnostic Techniques, Treatments, and Procedures
Chordotomy
Neurosurgical procedure for pain control accomplished through a laminectomy
Surgical interference of pathways within the spinal cord that control pain

80. Diagnostic Techniques, Treatments, and Procedures
Cisternal puncture
Insertion of a short, beveled spinal needle into the cisterna magna in order to drain CSF or to obtain a CSF specimen
Cisterna magna = shallow reservoir of CSF between the medulla and the cerebellum

81. Diagnostic Techniques, Treatments, and Procedures
Craniotomy
Surgical procedure that makes an opening into the skull
Echoencephalography
Measurement of electrical activity produced by the brain and recorded through electrodes placed on the scalp

82. Diagnostic Techniques, Treatments, and Procedures
Electroencephalography (EEG)
Measurement of electrical activity in the brain and recorded through electrodes
Sleep-deprived EEG
Individual deprived of sleep for 24 hours before test
Ambulatory EEG
Provides prolonged readings of electrical activity of brain over a 24-hour period of time, while person is awake or asleep

83. Diagnostic Techniques, Treatments, and Procedures
Laminectomy
Surgical removal of the bony arches from one or more vertebrae in order to relieve pressure from the spinal cord

84. Diagnostic Techniques, Treatments, and Procedures
Electromyography (EMG)
Process of recording electrical activity of muscle
Insert small needle into the muscle, deliver small current that stimulates the muscle

85. Diagnostic Techniques, Treatments, and Procedures
Lumbar puncture
Insertion of a hollow needle and stylet into subarachnoid space between third and fourth lumbar vertebrae below level of the spinal cord
Performed under strict aseptic technique

86. Diagnostic Techniques, Treatments, and Procedures
Magnetic Resonance Imaging (MRI)
Noninvasive scanning procedure that provides visualization of fluid, soft tissue, and bony structures without the use of radiation
Provides far more preciseness and accuracy than most diagnostic tools
Not limited to scans of the brain
May also be used to examine the abdomen, chest, joints, nervous system, pelvis, and spinal column

87. Diagnostic Techniques, Treatments, and Procedures
Myelography
Introduction of contrast medium into the lumbar subarachnoid space through a lumbar puncture in order to visualize the spinal cord and vertebral canal through x-ray examination

88. Diagnostic Techniques, Treatments, and Procedures
Neurectomy
Neurosurgical procedure to relieve pain in a localized or small area by incision of cranial or peripheral nerves
Pneumoencephalography
Process used to radiographically visualize one of the ventricles or fluid occupying spaces in the central nervous system (CNS)

89. Diagnostic Techniques, Treatments, and Procedures
Polysomnogram (PSG)
Sleep study or sleep test that evaluates physical factors affecting sleep
Physical activity and level of sleep are monitored by a technician while the patient sleeps
Useful in evaluating sleep disorders such as sleep apnea, sleep walking, night terrors, restless leg syndrome, insomnia, and narcolepsy

90. Diagnostic Techniques, Treatments, and Procedures
Positron Emission Tomography (PET Scan)
Computerized radiographic images of various body structures produced when radioactive substances are inhaled or injected
Romberg test
Examination used to evaluate cerebellar function and balance

91. Diagnostic Techniques, Treatments, and Procedures
Stereotaxic Neurosurgery
Neurosurgery on a precise location of an area within the brain that controls specific function(s)
May involve destruction of brain tissue with various agents such as heat, cold, and sclerosing or corrosive fluids

92. Diagnostic Techniques, Treatments, and Procedures
Sympathectomy
Surgical procedure used to interrupt a portion of the sympathetic nerve pathway, for the purpose of relieving chronic pain
Trichotomy
Through a craniotomy, the anterolateral pathway in the brain stem is surgically divided in an attempt to relieve pain

93. Diagnostic Techniques, Treatments, and Procedures
Transcutaneous Electrical Nerve Stimulation (TENS)
Form of cutaneous stimulation for pain relief that supplies electrical impulses to the nerve endings of a nerve close to the pain site