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Spinal Cord, Spinal Nerves, and Spinal Reflexes - Anatomy & Physiology

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Terms in this set (28)

  • What are the two main divisions of the nervous system?
    The Central Nervous System (CNS) includes the brain and spinal cord, and the Peripheral Nervous System (PNS) includes cranial and spinal nerves.
  • What is the function of spinal reflexes?
    Spinal reflexes are quick, automatic responses controlled by the spinal cord without input from the brain.
  • Describe the gross anatomy of the spinal cord.
    The spinal cord is a nervous tissue organ within the vertebral column, about 18 inches long, with 31 segments, containing gray matter (neuronal cell bodies) and white matter (myelinated axons).
  • What are the enlargements of the spinal cord and their significance?
    The cervical enlargement supplies nerves to the shoulder and upper limb, and the lumbosacral enlargement supplies nerves to the pelvis and lower limb.
  • What is the conus medullaris?
    The conus medullaris is the tapered, conical end of the spinal cord below the lumbar enlargement.
  • What are the two roots of a spinal nerve and their functions?
    The anterior (ventral) root contains motor neuron axons, and the posterior (dorsal) root contains sensory neuron axons.
  • What are the three meningeal layers surrounding the spinal cord?
    The meninges include the dura mater (outer layer), arachnoid mater (middle layer), and pia mater (inner layer).
  • What is the epidural space and its clinical significance?
    The epidural space lies between the vertebrae and dura mater, containing connective and adipose tissue; it is the site for epidural anesthesia.
  • What is the function of gray matter in the spinal cord?
    Gray matter contains neuronal cell bodies, neuroglia, and unmyelinated axons; it integrates information and initiates commands.
  • What is the function of white matter in the spinal cord?
    White matter contains myelinated and unmyelinated axons that carry information between different parts of the CNS.
  • Name the three regions (columns) of white matter in the spinal cord.
    The three white matter columns are the posterior white columns, anterior white columns, and lateral white columns.
  • What is a spinal nerve plexus?
    A nerve plexus is a complex network of nerve fibers formed from blended anterior rami of adjacent spinal nerves, allowing multiple nerves to supply the same structures.
  • List the four major nerve plexuses.
    The four major plexuses are the cervical, brachial, lumbar, and sacral plexuses.
  • What is a dermatome?
    A dermatome is a specific bilateral region of skin monitored by a single pair of spinal nerves.
  • What is the function of the phrenic nerve?
    The phrenic nerve controls the diaphragm and is part of the cervical plexus.
  • What nerves innervate the hand?
    The hand is innervated by the ulnar, median, and radial nerves from the brachial plexus.
  • What causes carpal tunnel syndrome?
    Compression of the median nerve in the carpal tunnel, often due to swollen tendons, causes carpal tunnel syndrome.
  • What are neuronal pools?
    Neuronal pools are functional groups of interconnected interneurons with limited input and output, involved in processing information in the CNS.
  • Describe the pattern of divergence in neuronal pools.
    Divergence spreads information from one neuron or pool to many, common in sensory pathways.
  • What is a reflex arc?
    A reflex arc is the neural pathway followed by nerve impulses to produce a reflex, usually involving a receptor, sensory neuron, interneuron, motor neuron, and effector.
  • What are the steps in a reflex arc?
    1) Stimulus activates receptor, 2) sensory neuron activated, 3) information processed in CNS, 4) motor neuron activated, 5) response by effector.
  • Differentiate between monosynaptic and polysynaptic reflexes.
    Monosynaptic reflexes involve a single synapse between sensory and motor neurons (fast), while polysynaptic reflexes involve one or more interneurons (slower).
  • What is the stretch reflex?
    The stretch reflex regulates skeletal muscle length by causing contraction of a muscle when it is stretched, e.g., the patellar reflex.
  • What is the role of the muscle spindle in the stretch reflex?
    Muscle spindles are sensory receptors detecting stretch in intrafusal fibers, triggering sensory neurons to activate motor neurons for muscle contraction.
  • What is reciprocal inhibition in reflexes?
    Reciprocal inhibition is when interneurons inhibit antagonistic muscles during a reflex, allowing one muscle to contract while the opposing muscle relaxes.
  • What is the crossed extensor reflex?
    A reflex that coordinates with the flexor reflex to straighten the opposite limb to support body weight when the other limb withdraws from a stimulus.
  • How can the brain modify spinal reflexes?
    Higher brain centers can facilitate or inhibit spinal reflexes by stimulating excitatory or inhibitory interneurons, adjusting reflex sensitivity.
  • What is the Babinski reflex and its clinical significance?
    The Babinski reflex is toe fanning in response to sole stroking, normal in infants but indicates CNS damage if present in adults.