MS (LEC)

• Organization of Central Nervous System: Brain

  Major regions include Diencephalon, Brainstem, Cerebrum, Cerebellum
• Cerebrum characteristics

  • Largest part of the brain, divided into left and right hemispheres, contains lobes such as Frontal, Parietal, Occipital, Temporal
• Nervous system divided into 2 regions

  1. Central nervous system (CNS): brain and spinal cord

  2. Peripheral nervous system (PNS): cranial nerves, spinal nerves, and autonomic nervous system
• Diencephalon regions

  • Thalamus influences mood and registers an unlocalized, uncomfortable perception of pain
  • Epithalamus involved in emotional and visceral response to odors, pineal body
  • Hypothalamus important in maintaining homeostasis, controlling body temperature, hunger, thirst, and hormone secretion
• Cerebellum


  • Composed of gray matter, located posterior and inferior
• Functions of the nervous system

  • Sensory input, integration, motor output, homeostasis, mental activity
• Brainstem components


  • Medulla Oblongata regulates HR, BV diameter, breathing, swallowing, vomiting, balance, coordination
  • Pons controls breathing, swallowing, balance, chewing, salivation
  • Midbrain involved in visual reflexes, auditory nerve pathways, eye movements, pupil diameter, lens shape
• Nervous system is involved in vital body functions such as the control of HR, BP, and breathing
• Auditory


  Hearing
• Sympathetic Nervous System

  • Originates from the T1 L2/L3 segments of the spinal cord (thoracolumbar)
  • Utilized for flight and fight response
  • Neurotransmitters are Epinephrine and Norepinephrine
• General categories of cranial nerves

  • Sensory
  • Motor
  • Mixed
• Lower motor neuron lesions result in loss of voluntary control, decreased muscle tone, flaccid muscle paralysis, muscle atrophy, and absent or decreased reflexes
• The spinal cord extends from the foramen magnum to the 2nd lumbar vertebra below which is the cauda equina
• Primary auditory cortex

  • Located in areas 41 and 42
• Auditory sensations play an important role in memory
• Parasympathetic Nervous System

  • CHOLINERGIC system
  • Involved in feed and breed responses
  • Cranio-sacral location
  • Neurotransmitter is Acetylcholine
• Wernicke’s area


  • Located in area 22, associated with Wernicke's aphasia (receptive, sensory, fluent, posterior)
• Structures supporting the brain include the skull and meninges (dura mater, arachnoid, pia mater)
• Cranial nerves

  • Sensory I, II, VIII
  • Motor III, IV, VI, XI, XII
  • Mixed V, VII, IX, X
• The spinal cord is surrounded and protected by the vertebral column
• Autonomic Nervous System is composed of Sympathetic (flight or fight) and Parasympathetic (rest and digest) divisions
• Upper motor neuron lesions result in loss of voluntary control, increased muscle tone, muscle spasticity, and hyperactive reflexes
• Cerebellum

  • Composed of gray matter
  • Posterior and inferior to the cerebrum
  • Involved in balance, maintenance of muscle tone, coordination of fine motor movements
  • Major function is that of a comparator
  • Also involves learning motor skills like riding a bicycle or playing a piano
• Photosynthesis

  1. Light energy is captured by chloroplasts and stored as ATP

  2. ATP is used to produce sugar, which the plant uses for growth and sustenance
• The peripheral nervous system consists of nerves and ganglia located outside the brain and spinal cord
• Cerebrospinal fluid bathes the brain and spinal cord, acts as a protective cushion, and is produced by the choroid plexus of the lateral, third, and fourth ventricles
• Blood-Brain Barrier


  • CNS is inaccessible to many substances
  • Formed by the endothelial cells of the brain's capillaries, creating BBB to macromolecules
  • Can be altered by trauma, cerebral edema, and hypoxia
• Cerebrospinal Fluid Production

  1. Produced by the Choroid plexus of the lateral, third, and fourth ventricles

  2. Clear, colorless, specific gravity of 1.007

  3. In normal adult, approximately 500 ml of CSF produced each day, all but 125 to 150 ml is absorbed by the villi
• Cerebrospinal Fluid


  • Bathes the brain and spinal cord
  • Protective cushion around the CNS
• Neurons


  • Basic functional unit of the brain
  • Composed of a cell body, dendrite, and an axon
  • Dendrite branch type structure with synapses for receiving electrochemical messages
  • Axon long projection that carries impulses away from the cell body
• Assessment of the Neurologic System

  1. Physical Examination: Cerebral function, Cranial nerves, Motor function, Sensory function, Reflexes

  2. Neuro check includes level of consciousness, pupillary size and response, verbal responsiveness, motor responsiveness, vital signs

  3. History: A confused client becomes an unreliable source of history

  4. Physical assessment to collect objective data including unilateral neglect, poor hygiene and grooming, abnormal gait and posture, emotional swings, personality changes, mask-like appearance on face, apathy
• Cerebral Function Assessment

  1. Assess the degree of wakefulness/alertness

  2. Note the intensity of stimulus to cause a response

  3. Apply a painful stimulus over the nailbeds with a blunt instrument

  4. Ask questions to assess orientation to person, place, and time

  5. Utilize the Glasgow Coma Scale to describe mental status and abnormality detection
• CSF Flow

  1. Cerebral Circulation receives approximately 15% of the cardiac output or 750 ml per minute

  2. Unique blood flow as it flows against gravity

  3. Poor collateral blood flow

  4. Two internal carotid arteries and two vertebral arteries empty into the dural sinuses
• Neurotransmitters

  • Acetycholine
  • Dopamine
  • Epinephrine and Norepinephrine
  • GABA (inhibitory)
  • Serotonin (↓ depression, ↑ manic)
  • Glutamine (excitatory)
• Cranial Nerve Function Assessment

  1. Cranial Nerve 1 Olfactory: Check patency of the nose, identify familiar substances

  2. Cranial Nerve 2 Optic: Check visual acuity, visual field, pupillary reflex, fundoscopy

  3. Cranial Nerve 3, 4, and 6: Assess movement of extraocular muscles, deviations like ophthalmoplegia
• Fundoscopy


  Check for papilledema
• Assessment of Reflexes (continued)

  1. Deep tendon reflex grading: 0 absent, + present but diminished, ++ normal average, +++ increased but not necessarily abnormal, ++++ hyperactive or clonic

  2. Superficial reflex grading: 0 absent, + present
• Assessment of Cranial Nerve 8 (Vestibuloauditory)

  1. Test patient's hearing acuity

  2. Observe for nystagmus and disturbed balance
• Assessment of Motor Function of the Brainstem

  1. Test for the Oculocephalic reflex doll's eye: Normal response eyes appear to move opposite to the movement of the head, Abnormal eyes move in the same direction

  2. Test for the Oculovestibular reflex: Slowly irrigate the ear with cold water and warm water
• Assessment of Cranial Nerve 12 (Hypoglossal)

  Ask the patient to protrude the tongue and note for symmetry