CHAPTER 8 Nervous System Nervous System Overview • Nervous System – Brain – Spinal cord – Nerves • Functions of nervous system – Regulates and coordinates all.
Download ReportTranscript CHAPTER 8 Nervous System Nervous System Overview • Nervous System – Brain – Spinal cord – Nerves • Functions of nervous system – Regulates and coordinates all.
CHAPTER 8 Nervous System Nervous System Overview • Nervous System – Brain – Spinal cord – Nerves • Functions of nervous system – Regulates and coordinates all body activities – Center of all mental activity, including thought, learning, and memory 2 Nervous System Divisions • Central Nervous System (CNS) – Brain – Spinal Cord • Processes and stores sensory and motor information • Controls consciousness 3 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 4 Nervous System Divisions 5 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 6 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 7 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 8 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 9 Cells of the Nervous System 10 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 11 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 12 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 13 Meninges • Arachnoid membrane – 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 14 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 15 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 16 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 17 Spinal Cord • Pathway for impulses traveling to and from brain • Carries 31 pairs of spinal nerves – Affects limbs and lower part of body 18 PATHOLOGICAL CONDITIONS Nervous System Alzheimer’s Disease • Pronounced – (ALTS-high-merz dih-ZEEZ) • Defined – Progressive and extremely debilitating deterioration of a person’s intellectual functioning 20 Amyotrophic Lateral Sclerosis (ALS) • Pronounced – (ah-my-oh-TROFF-ik LAT-er-al skleh-ROHsis) • Defined – Severe weakening and wasting of the involved muscle groups • Usually begins with hands • Progresses to shoulders, upper arms, then legs 21 Anencephaly • Pronounced – (an-en-SEFF-ah-lee) • Defined – Absence of the brain and spinal cord at birth • Condition is incompatible with life 22 Bell’s Palsy • Pronounced – (BELLZ PAWL-zee) • Defined – Temporary or permanent unilateral weakness or paralysis of muscles in the face 23 Brain Abscess • Pronounced – (BRAIN AB-sess) • Defined – Accumulation of pus located anywhere in the brain tissue 24 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 25 Cerebral Concussion • Pronounced – (seh-REE-bral con-KUSH-un) • Defined – Brief interruption of brain function usually with loss of consciousness lasting for a few seconds 26 Cerebral Contusion • Pronounced – (seh-REE-bral con-TOO-zhun) • Defined – Small, scattered venous hemorrhages in the brain – Bruise of the brain tissue – Occurs when brain strikes the inner skull 27 Cerebral Palsy • Pronounced – (seh-REE-bral PAWL-zee) • Defined – 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 28 Cerebral Palsy • Spastic – Damage to cortex of the brain • Tense muscles • Very irritable muscle tone • Ataxic – Damage to cerebellum • Affects equilibrium 29 Cerebral Palsy • Athetoid – Damage to basal ganglia • Causes sudden jerking • Rigidity • Causes child to be in continual state of tension • Mixed cerebral palsy 30 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 31 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 32 Degenerative Disk • Pronounced – (deh-JEN-er-ah-tiv disk) • Defined – Deterioration of the intervertebral disk • Usually due to constant motion and wear on the disk 33 Encephalitis • Pronounced – (En-seff-ah-LYE-tis) • Defined – 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 34 Epilepsy • Pronounced – (EP-ih-lep-see) • Defined – Syndrome of recurring episodes of excessive irregular electrical activity of the central nervous system, called seizures 35 Grand Mal Seizure • Pronounced – (grand MALL SEE-zyoor) • Defined – 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 36 Petit Mal Seizure • Pronounced – (pet-EE MALL SEE-zyoor) • Defined – Small seizures in which there is a sudden, temporary loss of consciousness • Lasts only a few seconds • Also known as absence seizures 37 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 38 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 39 Migraine Headache • Pronounced – (MY-grain headache) • Defined – 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 40 Cluster Headache • Pronounced – (KLUSS-ter headache) • Defined – Headache occurring typically two to three hours after falling asleep • Described as extreme pain around one eye that wakens the person from sleep 41 Tension Headache • Pronounced – (TEN-shun headache) • Defined – Headache that occurs from long, endured contraction of the skeletal muscles around the face, scalp, upper back, and neck 42 Epidural Hematoma • Pronounced – (eh-pih-DOO-ral hee-mah-TOH-mah) • Defined – Collection of blood located above the dura mater and just below the skull 43 Subdural Hematoma • Pronounced – (sub-DOO-ral hee-mah-TOH-mah) • Defined – Collection of blood below the dura mater and above the arachnoid layer of the meninges 44 Herniated Disk • Pronounced – (HER-nee-ay-ted disk) • Defined – 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 45 Huntington’s Chorea • Pronounced – (HUNT-ing-tonz koh-REE-ah) • Defined – Inherited neurological disease characterized by rapid, jerky, involuntary movements and increased dementia • Progressive, degenerative disease 46 Hydrocephalus • Pronounced – (high-droh-SEFF-ah-lus) • Defined – 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 47 Intracranial Tumors • Pronounced – (in-trah-KRAY-nee-al TOO-morz) • Defined – 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 48 Primary Intracranial Tumors • Pronounced – (PRIGH-mah-ree in-trah-KRAY-nee-al TOOmorz) • Defined – Tumors that arise from gliomas and the meninges • Gliomas = malignant glial cells that are a support for nerve tissue 49 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 50 Metastatic Intracranial Tumors (Secondary) • Pronounced – (met-ah-STAT-ik in-trah-KRAY-nee-al TOOmorz) • Defined – Tumors occurring as a result of metastasis from a primary site such as the lung or breast 51 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 52 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 53 Myasthenia Gravis • Pronounced – (my-ass-THEE-nee-ah GRAV-is) • Defined – Chronic progressive neuromuscular disorder • Causes skeletal muscle weakness (without atrophy) and fatigue • Occurring at different levels of severity 54 Narcolepsy • Pronounced – (NAR-coh-lep-see) • Defined – Rare syndrome of uncontrolled, sudden attacks of sleep – Main features of narcolepsy are daytime sleepiness and cataplexy – Sudden loss of muscle tone 55 Neuroblastoma • Pronounced – (noo-roh-blass-TOH-mah) • Defined – 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 56 Parkinson’s Disease • Pronounced – (PARK-in-sons dih-ZEEZ) • Defined – 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, pillrolling gestures, expressionless mask-like facial appearance 57 Peripheral Neuritis • Pronounced – (per-IF-er-al noo-RYE-tis) • Defined – Inflammation of one or more peripheral nerves – Effects are dependent upon particular nerve involved 58 Poliomyelitis • Pronounced – (poh-lee-oh-my-ell-EYE-tis) • Defined – 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 59 Post Polio Syndrome • Pronounced – (POST POH-lee-oh SIN-drom) • Defined – Progressive weakness occurring at least 30 years after the initial poliomyelitis attack 60 Reye’s Syndrome • Pronounced – (RISE SIN-drom) • Defined – 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 61 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 62 Shingles Image courtesy of Robert A. Silverman, M.D., Pediatric Dermatology, Georgetown University 63 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 64 Spina Bifida Cystica • Pronounced – (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 65 Meningocele • Pronounced – (men-IN-goh-seel) • Defined – Cystlike sac covered with skin or a thin membrane protruding through the bony defect in the vertebrae containing meninges and CSF 66 Meningomyelocele • Pronounced – (men-in-goh-my-ELL-oh-seel) • Defined – 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 67 Spina Bifida Occulta • Pronounced – (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 68 Paraplegia • Pronounced – (pair-ah-PLEE-jee-ah) • Defined – 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 69 Quadriplegia • Pronounced – (kwod-rih-PLEE-jee-ah) • Defined – 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 70 Tay-Sachs Disease • Pronounced – (TAY SACKS dih-ZEEZ) • Defined – 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 71 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 72 DIAGNOSTIC TECHNIQUES, TREATMENTS, AND PROCEDURES Nervous System 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 74 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 75 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 76 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 77 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 78 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 79 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 80 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 81 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 82 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 83 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 84 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 85 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 86 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 87 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) 88 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 89 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 90 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 91 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 92 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 93