M8

• Central Nervous System 


  Consists of the brain and spinal cord. Processes incoming sensory information. Stimulate muscles to contract and glands to secrete.

  
• Divisions of the Nervous System

  • Nerves
  • Ganglion (Ganglia)
  • Enteric plexuses
  • Sensory receptors

  
• Peripheral Nervous System

  1. Somatic Nervous System (SNS) (Voluntary)

  2. Autonomic Nervous System (ANS) (Involuntary)

  3. Enteric Nervous System (ENS) (Involuntary)

  
• Neurons


  Receive stimuli, conduct action potentials, and transmit signals to other neurons or effector organs
• Parts of a Neuron

  • Cell Body
  • Dendrites
  • Axon

  
• Glial Cells


  Supportive cells that do not conduct action potentials. Carry out functions that enhance neuron function and maintain normal conditions within nervous tissue.

  
• Myelin Sheaths


  Specialized layers that wrap around axons of some neurons, formed by glial cells. Myelinated axons conduct action potentials more quickly than unmyelinated.
• Nodes of Ranvier


  Gaps in the myelin sheath that occur between individual Schwann cells.
• Spinal Cord


  Extends from foramen magnum to 2nd lumbar vertebra. White matter consists of myelinated axons, gray matter is a collection of neuron cell bodies.
• Types of Pathways in the Spinal Cord Columns

  • Ascending Tracts
  • Descending Tracts
• Treatment for Cauda Equina Syndrome

  Urgent/emergent surgery to free up the compressed nerve roots and give them the best chance of recovery possible.
• Knee-Jerk Reflex (Patellar Reflex)


  Stretch reflex where tapping the patellar ligament activates the stretch reflex in the quadriceps femoris muscle.
• Withdrawal Reflex (flexor reflex)


  Reflex to remove a limb or body part from a painful stimulus.
• Spinal Nerves

  • Cervical (C1 to C8)
  • Thoracic (T1 to T12)
  • Lumbar (L1 to L5)
  • Sacral (S1 to S5)
  • Coccygeal (Co)
• Dermatome


  Area of skin supplied with sensory innervation by a pair of spinal nerves.
• Plexus


  Area where neurons of spinal nerves come together and intermingle.
• Important Spinal Nerve Plexuses

  • Cervical plexus C1-C4 inervates the phrenic nerve
  • Brachial plexus (upper limb) C5-T1
  • Lumbosacral plexus (lower limb) L1-S4
• Brain Regions

  • Brainstem
  • Cerebellum
  • Diencephalon
  • Cerebrum

  
• Components of the Brainstem


  • Medulla Oblongata
  • Pons
  • Midbrain
• Medulla Oblongata


  Extends from foramen magnum to pons. Contains nuclei involved in regulating heart rate, blood vessel diameter, breathing, swallowing, vomiting, coughing, sneezing, balance.
• Pons


  Serves as a functional bridge between the cerebrum and cerebellum, involved in breathing, swallowing, balance, chewing, salivation.
• Midbrain


  Involved in coordinated eye movements, controlling pupil diameter, and lens shape.
• Components of the Diencephalon

  • Thalamus
  • Epithalamus
• Thalamus


  Influences moods and detects unlocalized pain.
• Medulla oblongata

  Arched Footbridge – anterior surface; aids in assisting functions of medulla oblongata
• Medulla oblongata


  • Serves as functional bridge between cerebrum & cerebellum, breathing, swallowing, balance, chewing, salivation
• Midbrain


  Smallest region; superior to the pons
• Superior Colliculi


  • 2 mounds; involved in visual reflexes & receive touch & auditory input
• Inferior Colliculi


  • Major relay centers for auditory nerve pathways in CNS
• Substantia Nigra


  • Black nuclear mass that is involved in regulating general body movements
• Midbrain


  • Coordinated eye movements, controlling pupil diameter, lens shape
• Diencephalon


  Part of brain between brainstem & cerebrum

  
• Thalamus


  Largest part; consists of cluster of nuclei shaped like a yo-yo; Interthalamic Adhesion – centrally connect the two large, lateral parts
• Epithalamus


  Small area superior & posterior to thalamus; consists of few small nuclei
• Pineal Gland


  • An endocrine gland that influences the onset of puberty & controlling some long-term cycles that are influenced by the light-dark cycle
• Epithalamus


  • Emotional & visceral response to odors
• Hypothalamus


  Most inferior part; below thalamus; contains several small nuclei
• Infundibulum


  • A funnel-shaped stalk that extends from the floor of hypothalamus to pituitary gland
• Mammillary Bodies


  • Visible swelling on posterior part of hypothalamus that are involved in emotional responses to odors and memory

  
• Hypothalamus


  • Plays a central role in maintaining homeostasis, control of body temperature, hunger, thirst, sexual pleasures, rage, fear, relaxation after meal, control the secretion of hormone from pituitary gland