Spinal Cord and Spinal Nerves

• What is the primary function of the spinal cord?

  It serves as a path of communication between the brain and the body.
• Why does nervous tissue not repair itself well?

  Because it does not respond to damage effectively.
• What structures provide protection to the CNS?

  Skull, vertebral column, meninges, and cerebrospinal fluid.
• What are the three layers of the meninges?

  Dura mater, arachnoid mater, and pia mater.
• What is the function of cerebrospinal fluid?

  It suspends the nervous tissue of the CNS.
• What does the vertebral foramen create when vertebrae are stacked?

  It creates the vertebral canal.
• What is the location of the spinal cord?

  Within the vertebral canal of the vertebral column.
• What is the dura mater?

  The most superficial layer of the meninges, made of thick, strong connective tissue.
• Where does the dura mater form a sac around the spinal cord?

  From the foramen magnum to the 2nd sacral vertebrae.
• What is the epidural space?

  The space outside the dura mater.
• What is the arachnoid mater?

  The middle layer of the meninges that is avascular.
• What is the appearance of the fibers in the arachnoid mater?

  They have a spider web appearance.
• What does the pia mater adhere to?

  The surface of the spinal cord and brain.
• What are denticulate ligaments?

  Thickenings of pia mater that prevent displacement of the spinal cord.
• What is the conus medullaris?

  The terminal end of the spinal cord at the superior border of the 2nd lumbar vertebra.
• What is the filum terminale?

  An extension of pia mater that anchors the spinal cord to the coccyx.
• How many pairs of spinal nerves are there?

  31 pairs of spinal nerves.
• How are spinal nerves named?

  Based on the segment where they are located.
• What are the types of spinal nerves?

  Cervical, thoracic, lumbar, sacral, and coccygeal nerves.
• What do the posterior roots of spinal nerves contain?

  Only sensory axons from receptors in the skin, muscles, and internal organs.
• What is the spinal ganglion?

  An enlargement within each dorsal root containing cell bodies of sensory neurons.
• What do the anterior roots of spinal nerves contain?

  Axons of motor neurons that conduct impulses from the CNS to effectors.
• How do spinal nerves at the cervical and thoracic levels differ from those at the lumbar, sacral, and coccygeal levels?

  Cervical and thoracic spinal nerves extend laterally, while lumbar, sacral, and coccygeal nerves angle inferiorly.
• What is the cauda equina?

  A collection of spinal nerves within the inferior vertebral column inferior to the conus medullaris.
• What does the gray matter of the spinal cord contain?

  Dendrites, cell bodies, unmyelinated axons, and neuroglia.
• How does white matter differ from gray matter in the spinal cord?

  White matter contains bundles of myelinated axons, while gray matter contains cell bodies and unmyelinated axons.
• What divides the spinal cord into right and left halves?

  Two grooves: anterior median fissure and posterior median sulcus.
• What does the gray commissure connect?

  The two sides of gray matter in the spinal cord.
• What is the central canal filled with?

  Cerebrospinal fluid.
• What are sensory nuclei in the gray matter?

  Clusters of neuron cell bodies that receive input via sensory neurons.
• What do the posterior gray horns contain?

  Axons of incoming sensory neurons and cell bodies of interneurons.
• What do the anterior gray horns contain?

  Somatic motor nuclei that provide nerve impulses to skeletal muscles.
• What do the lateral gray horns contain?

  Autonomic motor nuclei that regulate cardiac muscle, smooth muscle, and glands.
• What are funiculi in the spinal cord?

  Regions or anatomic divisions of the white matter.
• What do sensory tracts do?

  Conduct impulses toward the brain.
• What are the types of tracts in the spinal cord?

  Sensory tracts (ascending) and motor tracts (descending).
• What do motor tracts do?

  Conduct impulses away from the brain.
• How are sensory and motor tracts of the spinal cord related to the brain?

  They are continuous with tracts of the brain.
• What are the steps in spinal cord processing of sensory input and motor output?

  1. Sensory receptors detect a sensory stimulus.
  2. Sensory neurons convey sensory input as nerve impulses.
  3. Sensory axons pass through the posterior gray horn into the white matter and ascend to the brain.
  4. Sensory axons synapse with interneurons in the posterior gray horn.
  5. Axons carry impulses from the brain down motor tracts to the anterior gray matter.
  6. Somatic motor neurons convey motor output to skeletal muscle.
  7. Autonomic motor neurons convey motor output to cardiac muscle, smooth muscle, and glands.
  8. Axons of autonomic motor neurons synapse with effectors.
• What are spinal nerves part of?

  The peripheral nervous system.