Spinal Muscle Review

Question 1

define the dura matter and how it interacts with surrounding anatomy

Answer 1

• outer layer of meninges (technically bilaminar)
  
  • goes from tightly fused to bone -> not fused to bone
    
    • in the skull: tightly fused to periosteum
    • in the spinal (vertebral) canal:
      
      • surrounding spinal cord:
        
        • laterally extends to:
          
          1. ventral & dorsal roots
          2. spinal ganglion
          3. proximal spinal nerve - i.e., up until intervetebral foramen
        • inferiorly extends to:
          
          • S2 (so, including conus medullaris)
      • separated from periosteum + ligaments

Question 2

at what point does the dura matter lose its tight fusion to periosteum?

what does this result in?

Answer 2

• at the foramen magnum
• creates the epidural space: space between the dura and surrounding periosteum ligaments within the vertebral canal. this space contains the:
  
  • adipose tissue mostly
    
    • internal vertebral venous plexus
    • recurrent meningeal nerve

Question 3

what key neurovasculature is found in the epidural space? describe

Answer 3

• internal vertebral venous plexus: wraps around dura (which surrounds spinal canal)
• recurrent meningeal nerve: peels off spinal nerve & heads back to spinal cord via intervertebral foramina, carrying sensory info from vertebra / meninges on the way

Question 4

how is the spinal dura positioned relative to the epidural space?

Answer 4

dura = deep to epidural space

Question 5

inferiorly, where does the dura end?

describe the pertinent anatomy surrounding this inferior portion of dura

Answer 5

• dura ends at S2
  
  • between conus medularis (end of spinal cord) and S2: the lumbar cistern resides:
    
    • _​_CSF filled cavity
    • also “subarachnoid space”
  • beyond S2: the filum terminal extends to tether dura to the sacral hiatus

Question 6

what is the filum terminale?

Answer 6

a tether connecting the inferior end of the dura matter (at S2) to the sacral hiatus

Question 7

what & where is the lumbar cistern?

Answer 7

• is a CSF filled cavity that
  
  • runs from conus medullaris (end of spinal cord) to S2 (end of dura matter)
  • is within the subarachnoid space: i.e., between arachnoid and pia matter

Question 8

what is the arachoid mater?

describe pertinent attachements / compartments

Answer 8

• middle layer of meninges
• compartments:
  
  • between arachnoid and dura: subdural space
  • between arachnoid and pia: subarachnoid space

Question 9

what is the pia mater?

describe pertinent attachments / comparments

Answer 9

• the innermost layer of the meninges
• comparments attachments:
  
  • subarachnoid space: between pia mater and subarachnoid mater
    
    • lumbar cistern = subarachnoid space between conus medullaris and S2
  • denticulate ligaments: lateral extensions that integrate with outer meningeal layers

Question 10

describe the denticulate ligamnets & their role

Answer 10

• are pia matter thickenings - that extend laterally between the ventral & dorsal roots of each spinal segment of a spinal segment (1 per at spinal segment)
• provide position stability to the spinal canal by integrating into surrounding mengies (both arachnoid & dura)

Question 11

where are the spinal arteries located?

how are they pertinent pathologically?

Answer 11

• course along the length of the spinal cord
  
  • one anterior spinal artery
  • two posterior spinal arteries
• infarcts are more common in anterior spinal arery

Question 12

what defines a spinal segment?

describe the structures involved in a spinal segment.

Answer 12

• spinal segments are defined by a discrete group of spinal nerve rootlets
  
  • made of:
    
    • spinal rootlets: paired (dorsal/sensory & ventral/motor) emerge lateral to the spinal cord
    • spinal roots: paired (dorsal/sensory & ventral/motor) form from roots
      
      • dorsal root -> dorsal root ganglion on the way to spinal nerve
    • spinal nerve: forms from roots just beyond intervertebral foramen

Question 13

what defines the spinal nerve proper?

describe the structures involved in the spinal nerve proper:

Answer 13

• defined by the adjacent vertebrae
  
  • cervical: same # as inferior vertebrae, except between C7-T1 = C8
  • remainder: same # as superior vertebrae (ex - L3 between L3 & L4)
• structures:
  
  • spinal nerve: forms outside ntervertebral foramen, & gives off
    
    • ventral & dorsal rami - run along respective sides of TP:
      
      • ventral rami (ventral to TP), gives off
        
        • rami communicanes: part of ANS, as they links spinal nerve to sympathetic chain ganglion:
          
          • grey ramus - medial
          • white ramus - lateral
      • dorsal rami (dorsal to VP)