Nervous System

1. Nervous System Chapter 14 Medical Terminology

2. Nervous System • System of conducting tissues (nerves) that receive information from the environment and control both voluntary and involuntary functions of the body and consciousness

3. Cellular Anatomy • Two types of cells: • Neurons • Transmit impulses (conduct) • Sensory neurons (afferent) • Motor neurons (efferent) • Mixed (both afferent and efferent) • Neuroglia • Supporting cells

4. Neurons: Structure • Cell body • Nucleus, cytoplasm, organelles • Dendrites • Projections of the cell body • Receive and carry impulses • Axons • Single, long projections from cell body • Also transmit impulses

5. Neurons: Structures • Myelin sheath • Covering outer layer of axon • Lipid layer • White color • Makes up the white matter in CNS • Acts as an insulator • Speeds up impulse transmission in the axon

6. More about myelin • Unmyelinated structures • Appear gray, gray matter • CNS and spinal column • Peripheral nerve (PNS) • Schwann cell = myelin sheath • Neurilemma/neurolemma = this thin layer • Node of Ranvier = space between Schwann cells

7. Neurons: Other terms • Synapse • Space between neurons • Between axon terminal and dendrites of adjacent neurons • Axon terminal • Neurotransmitter

8. Neuroglia: Four Types Astrocytes star shaped support cells for neurons form capillary sheaths (BBB) Oligodentrocytes help in CNS myelin development Microglia: phagocytes

9. Neuroglia: Four Types • Ependyma • Ciliated cells • Line cavities in CNS (ventricles) • Help CSF circulation

10. Nervous System Anatomy • Central Nervous System (CNS) • Brain • Spinal Cord • Peripheral Nervous System (PNS) • 12 pairs of cranial nerves (CN I-XII) • From basilar surface of brain • 31 pairs of spinal nerves • From spinal cord

11. CNS Anatomy: Brain Meninges three protective membranes around CNS Cerebrum corpus callosum structures connecting hemispheres gyri (gyrus) = folds or convolutions sulci (sulcus) =fissues, furrows

12. CNS Anatomy: Brain • Lobes of the brain: • Frontal • Parietal • Temporal • Occipital • Insula

13. Brain Anatomy • Cerebral Cortex • Thin outer layer • Gray matter due to millions of cell bodies • Rest of cerebrum is myelinated axons (white) • Cerebrum: Functions • Sensory perception, interpretation • Voluntary movement, language, memory • Emotional aspects of behavior

14. Other Structures in the Brain: • Cerebellum • Posterior aspect • Coordinates and refines movement • Balance and equilibrium

15. Other Brain Structures • Diencephalon (interbrain) • Thalamus • Receives & transmits all sensory info except smell to the cerebrum • Transmits impulses from cerebrum to efferents • Hypothalamus • Coordinates autonomic impulses • Temperature regulation • Control of endocrine system

16. Other Brain Structures: • Brainstem: control of respiration, cardiac activity • Pathway between brain and spinal column • Midbrain (mesencephalon) • Medulla (oblongata) • pons

17. CNS structures: Spinal Cord • Ascending tracts • Bring sensory input to CNS • Descending tracts • Send impulses to muscles, end organs • Cross-section: • Gray matter-inner part of cord • White matter—outer part of cord • Spinal cavity • Spinal nerves exit from intervertebral spaces • Cauda equina

18. CNS: Meninges • Dura • Outermost, very fibrous • Subdural space: filled with serous fluid • Arachnoid • Thinner, looks like a spider web • Subarachnoid space: contains CSF • Pia • Innermost layer, also thin • Contains blood vessels and lymphatics

19. Peripheral Nervous System (PNS) • Cranial Nerves • Spinal Nerves • Somatic Nervous system (SNS) • Autonomic Nervous system (ANS)

20. PNS: Cranial Nerves • Exit mostly from base of the brain • Named and denoted by I through XII • Mostly involve facial, eye, mouth movement and sensation and the special senses of hearing, taste, sight • Are afferent, efferent, and mixed nerves

21. PNS: Spinal Nerves • Exit from spinal cord and go to muscles and organs • Each has two attachments to spinal cord: • Anterior root: motor fibers • Posterior root: sensory fibers

22. Somatic Nervous System (SNS) • Voluntary functions • Mostly supplies skeletal muscles

23. Autonomic Nervous System (ANS) • Supplies nerves (ennervates) involuntary functions • Ennervates glands, smooth & cardiac muscles, etc • Sympathetic system • Fight or flight • Parasympathetic system • Functions that are the opposite, resting

24. Medical Word Elements • Cerebro: cerebrum • Cranio: cranium or skull • Encephalo: brain • Kinesio: movement • Ganglio: knot or mass (a ganglion) • Narco: sleep, stupor • Neuro: nerve

25. Medical word elements: • Radiculo: nerve root (radiculopathy) • Theco: sheath (intrathecal) • Tono: tension (tonometry, dystonic)

26. Medical Word Elements • Others are from anatomic structure names • Ventriculo: ventricles • Thalamo: thalamus • Myelo: spinal cord or bone marrow • Meningo: meninges • Glio: neuroglial tissue • Dentro: treee-like

27. Suffixes: Neuro • -algia or algesia: pain • -asthenia or –paresis: weakness, disability • -esthesia: feeling • -kinesia: movement • -lepsy: seizure (epilepsy, narcolepsy) • -phasia: speech • -plegia: paralysis

28. Suffixes: Neuro • -plexy: stroke • -taxia: coordination (ataxia) • -trophy: development

29. Prefixes: Neuro • Contra- = against/opposite • Pachy- = thick • Para- = near • Syn- = together, joined

30. Neurological Pathology • Common symptoms: • Pain (head, neck, back, periphery) • Abnormal movements • Gait abnormalities • Disturbances of special senses • Speech abnormalities • Altered level of consciousness • Focal weakness • seizures

31. Bell’s Palsy • Facial paralysis (unilateral usually)) • Involves CN VII • Herpes viral infection • Usually transient • Facial weakness and numbness, problems with blink reflex and speech

32. Cerebrovascular Disease • Cerebrovascular accident (CVA) or stroke • Focal loss of function due to loss of blood supply • Lasts more than 24 hours • Causes: • Ischemic: due to thrombus or carotid emboli (75%) • Hemorrhagic (25%) • Extrinsic compression of blood vessel (rare)

33. Cerebrovascular Disease • Typical CVA symptoms: • Anterior stroke: • Hemiparesis or hemiplegia • Aphasia or dysphasia • Partial loss vision/ visual field • Posterior stroke: • Balance problems, ataxia, vertigo

34. Cerebrovascular Disease • Transient Ischemic Attack (TIA) • Focal symptoms like a CVA, lasting less than 24 hours • Typical symptoms: weakness or clumsiness of upper extremity, visual field loss, hemiparesis of the face, paresthesias of upper extremities • Indicates risk of CVA within next year

35. Seizure Disorders • Nerve conduction dysrhythmias • Epilepsy = chronic seizure disorder • Generalized Sz (gran mal, tonic clonic) • Movements of entire body • unconsciousness • Partial Sz (focal) (Jacksonian) • Petit mal (absence Sz)

36. Seizure Disorders: Causes • Congenital anomalies • Brain injury • Metabolic disease • Brain tumors • Genetic disorders • Vascular anomalies

37. Seizures: • Are often the symptom of the disease • Status epilepticus • Life-threatening • Lengthy or muliple Sz • Electroencephalography • Magnetoencephalography • Rx: antiepileptic meds

38. Parkinson Disease • Parkinsonism also • A movement disorder • Progressive neurological disease affected the movement control centers of the brain • Deficiency of dopamine, a neurotransmitter in the brain • Rx: L-dopa administration

39. Parkinson Disease • Symptoms: • Bradykinesia or hypokinesia • Uncontrollable shaking of head • Shuffling gait, pill rolling of fingers • Tremors • Some stiffness, • Mask-like facial expressions

40. Multiple Sclerosis (MS) • Progressive demyelinating disease of CNS • Impeding nerve conduction • Disease of young adults, usually females • Autoimmune disease suspected, fatal • Symptoms: • Tremors, bradykinesias • Visual disturbances, muscle weakness

41. Alzheimer Disease • Progressive, fatal neurological degenerative disease of the elderly • Memory loss, cognitive dysfunction, anxiety, decline in social skills and ADL • Plaques develop in cerebral cortex • Common cause of senile dementia in US • Some medications slow progress of disease

42. Mental Illnesses • Alterations in behavior, mood, thought • Some general terminology: • Phobia • Delusion • Hallucinations • Obsessive compulsive disorders (OCD) • Psychiatrist or clinical psychologist

43. Categories of Mental Illnesses • Affective (mood) disorders • Mania • Depression • Manic-depressive disorder (bipolar disorder) • Eating disorders • Anorexia nervosa • Bulimia nervosa

44. Categories of Mental Illnesses • Anxiety disorders • Panic attacks • Attention-deficit hyperactivity disorder (ADHD) • Schizophrenia (thought disorder)

45. Neuro Oncology • Most intracranial neoplasms are primary brain tumors • Papilledema = classic sign of intracranial tumor, slowly rising ICP • Metastatic tumors to brain • Fairly common, slower growing than their primary tumors, more easily resected than primary CNS tumors

46. Neuro Infections • Meningitis • Bacterial = most rapid, meningococcal • Viral or fungal • Encephalitis • Usually viral • Brain or Spinal Cord abscesses • Usually bacterial • Parasitic also possible

47. Intracranial Hemorrhages • Epidural hemorrhage • Subdural hemorrhage • Subarachnoid hemorrhage • Intracerebral hemorrhage

48. Epidural Hemorrhage • Arterial bleeding • Often involves parietal skull fracture • Disrupts the middle meningeal artery • Famous “lucid interval” symptoms • Usual symptoms: headache, unconsciousness, unilateral weakness or abnormal reflexes

49. Subdural Hemorrhage • Venous bleeding from the bridging veins • Slower bleed • Symptoms: similar to EDH but no lucid interval

50. Subarachnoid Hemorrhage • Thin filmy layer of blood around the brain and cord • May be spontaneous or due to trauma • Symptoms and Signs: • “the worst headache of my life” • Sudden onset • Nuchal rigidity • Photophobia, nausea, vomiting