CNS - SPINAL CORD

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					Spinal Cord
Spinal Cord
 ~ Width of thumb
 2 Functions:
  Reflex center – spinal reflexes
  Conduction pathways
    sensory  brain
              brain  motor
CNS Protected by:

1.Bone

2. Meninges

3. CSF
4 Regions

•Cervical

•Thoracic

•Lumbar

•Sacral
Spinal Cord & Spinal Nerves

  Extend from the medulla oblongata to
   12th thoracic vertebra (T12)
  Enlargements occur in the cervical and
   lumbar regions
  31 pairs of spinal nerves attach to cord
   by paired roots
  Exit through openings in vertebrae &
   go to body regions served
Cauda equina: “Horse’s Tail”

  In embryo,
   vertebral column
   grows faster than
   spinal cord 
   lower spinal
   nerve roots
   “chase” exit
   points inferiorly
Spinal Cord Organization




  Spinal Nerve Roots
Spinal Cord Organization

 1. Exterior white matter
   a. Myelinated & unmyelinated axon fibers
   b. Sensory input (ascending, afferent)
   c. Motor output (descending, efferent 
      effector)
   d. Tracts with similar function & destination
      tend to be located together

     *Tracts =
2. Internal gray matter
 Cell bodies
   a. “Butterfly” shape
   b. Dorsal horn -
   c. Ventral horns -
Spinal Cord Trauma & Disorders

  Paralysis = loss of
   movement

  Parasthesia = sensory loss
Spastic paralysis

  Results from transection of spinal
   cord (cut crosswise or crushed)
  Affected muscles still stimulated by
   spinal reflex arcs
  Muscles can move, however,
   movement is involuntary, not
   controllable
 Loss of sensory input in areas below
  point of injury
 Location of injury determines
  whether person is
 Quadriplegic (arms & legs affected)
 Paraplegic (legs only)
Flaccid paralysis

    Occurs when nerves stimulating skeletal
     muscles are damaged (ventral root or
     anterior horn cells)
    Muscle atrophies
Spinal shock

  Transient period following injury to spinal
   cord
  Depression of all reflex activities inferior
   to injury site
  Victim may recover function within 24
   hours

				
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posted:5/3/2012
language:English
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