Spinal cord & spinal nerves CH 17

• 3 fxn’s of spinal cord

  •conducts sensory & motor impulses

  •coordinataion for locomotion (walking)

  •reflexes
• Outer cord includes

  ascending tracts & descending tracts
• Ascending tracts (in outer cord)-


  sensory
• Descending tracts (in outer cord)-

  Motor
• coordination for locomotion (2nd spinal cord fxn) includes

  Simple repetitive patterns w/no sensory motor feedback
• In terms of coordination for locomotion (2nd fxn), Central Patter Generators (CPG’s)-


  stimulate specific muscles @ certain times
• Reflexes-

  rapid involuntary Response
• Spinal cord begins @

  Foramen magnum
• Spinal cord is vital link b/n

  brain & body
• Outer protective layer is

  Vertebral column
• SC has protective structures called

  meninges
• Dura mater (1st meninge)

  •”Tough Mother”

  •continuous from SC

  •dense irreg CT

  •subdural space

  ISF
• Arachnoid layer aka middle layer (2nd protective structure/meninge)-

  •”spider-like”

  •collagen & some elastin

  •subarachnoid space

  CSF
• Pia mater (3rd meninge/protective structure)

  •delicate

  •innermost

  •squamous-cuboidal cells

  •highly vascularized

  •adheres to SC & brain

  •denticulate ligaments
• Pia mater (3rd protective structur/meninge) includes denticulate ligaments which 


  Extend to arachnoid/dura, secure SC in place
• External anatomy of SC

  •oval shaped, flattened ant/post

  •medulla oblongata to L2
• External anatomy of SC includes 2 enlargements which include

  Cervical & Lumbar
• Cervical (C4-T1)-

  Upper limbs
• Lumbar (T9-T12)-


  Lower limbs
• at the tip of the spinal cord we have the

  Conus medularis
• Conus medularis (tip of spinal cord)-

  Tapering of SC inferiorly (L1-L2)
• Filum terminale- 


  anchors the spinal cord in place
• Filum terminale (anchors SC in place):

  -extensions of the pia mater fusing w arachnoid & dura mater

  -anchors SC to sacrum
• Cuada equina “horse’s tail”


  -spinal nerves exiting SC, traveling inferiorly
• CC: spinal tap vs epidural

  Needle inserted into subarachnoid space

  •to draw CSF

  •for diagnostics

  •to provide antibiotics

  •chemotherapy

  •anesthetics (spinal)
• Epidurals are 


  Inserted into the epidural space, includes catheter to modulate pain
• 2 grooves (of Internal anatomy of the SC) that divide

  R & L
• 1st groove (of internal anatomy of SC) is the

  Anterior median fissure
• 2nd groove (of the internal anatomy of the SC) includes

  Posterior median sulcus
• Grey matter (of internal anatomy of SC)

  •cell bodies, neuroglia, unmyelinated axons, dendrites of motor & interneurons
• Grey commissure (of internal anatomy of SC)

  Grey composure-connects L & R
• Central canal:

  CSF
• Nuclei=


  clusters of cell bodies
• 3 regions of spinal cord (of the grey matter) include

  1.Anterior/Ventral horn

  2.Posterior/Dorsal horn

  3.Lateral horn
• Anterior/Ventral horn (1st region of SC of grey matter)


  -LMN (motor)
• Posterior/Dorsal horn (2nd region of SC of grey matter)

  -sensory & interneuron
• Lateral horn (3rd region of SC of grey matter)


  -autonomic
• in the internal structure of the SC, the grey matter is

  Deep to the white matter, opposite to the cerebrum
• Grey matter is

  butterfly shaped, central
• White matter:

  Myelinated axons, ascending & descending the SC