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Spinal Cord Anatomy and Physiology

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Terms in this set (18)

  • Anatomy of the spinal cord
    The spinal cord is a cylindrical structure composed of gray and white matter, protected by vertebrae and meninges, extending from the brainstem to the lumbar region.
  • Overall functions of the spinal cord
    The spinal cord transmits sensory information to the brain, motor commands from the brain to muscles, and coordinates reflexes.
  • Regional functions of the spinal cord
    Different spinal cord segments control specific body regions; cervical controls arms, thoracic controls trunk, lumbar controls legs.
  • Three meningeal layers surrounding the spinal cord
    • Dura mater: outer tough layer
    • Arachnoid mater: middle web-like layer
    • Pia mater: inner delicate layer attached to spinal cord
  • Organization of gray matter in the spinal cord
    Gray matter is butterfly-shaped, containing neuron cell bodies, divided into dorsal (sensory), ventral (motor), and lateral horns.
  • Organization of white matter in the spinal cord
    White matter surrounds gray matter and contains myelinated axons organized into ascending sensory and descending motor tracts.
  • Major components of a spinal nerve
    Each spinal nerve has a dorsal root (sensory fibers), ventral root (motor fibers), and a mixed nerve trunk.
  • Distribution of motor and sensory fibers
    Sensory fibers enter the spinal cord via dorsal roots; motor fibers exit via ventral roots to muscles.
  • Importance of dermatomes
    Dermatomes are skin areas innervated by sensory fibers from a single spinal nerve, useful for diagnosing nerve damage.
  • Nerve plexuses
    Networks of intersecting spinal nerves (e.g., cervical, brachial, lumbar, sacral) that redistribute fibers to limbs.
  • Patterns of neuron interaction in neural pools
    Neurons interact via divergence, convergence, serial processing, parallel processing, and reverberation.
  • Major steps in a reflex arc
    1. Receptor detects stimulus
    2. Sensory neuron transmits signal
    3. Integration center processes info
    4. Motor neuron sends response
    5. Effector executes response
  • Classification of reflexes
    Reflexes are classified by development (innate/acquired), response type (somatic/autonomic), complexity (mono/poly synaptic), and processing site (spinal/cranial).
  • Monosynaptic reflex structure and function
    A monosynaptic reflex (e.g., stretch reflex) involves one synapse between sensory and motor neurons, producing a quick muscle contraction.
  • Polysynaptic reflexes examples
    Polysynaptic reflexes (e.g., withdrawal and crossed-extensor) involve interneurons and multiple synapses for complex responses.
  • Withdrawal reflex
    A polysynaptic reflex causing limb withdrawal from painful stimuli, involving sensory input, interneurons, and motor output.
  • Crossed-extensor reflex
    A polysynaptic reflex that stabilizes the body by extending the opposite limb when the other limb withdraws.
  • Higher center control of reflexes
    Brain centers can modulate reflex strength and response via descending pathways to spinal cord neurons.