Vertebral Column

Question 1

What is within the vertebral canal?

Answer 1

• Spinal Cord
• Epidural Space (real space):
  
  • Contains fat, blood vessels, veins and arteries
• Meninges (CNS covering)
  
  • Protect and anchor spinal cord

Question 2

Differentiate the meningeal layers.

Answer 2

• Dura Mater “Tough Mother”
  
  • Outermost layer of dense CT
  • Extends to S2 Vertebra (Dural Sac)
• Arachnoid Mater
  
  • “Spider-web material”
• Pia Mater
  
  • ​Innermost layer
  • Adheres directly to spinal cord
  • Specializations:
    
    • Denticulate Ligaments (stabilize spinal cord laterally)
    • Filum Terminale (stabilize spinal cord inferiorly)

Question 3

Describe the spaces between meninges.

Answer 3

• Subdural Space:
  
  • Potential Space
  • Space between dura and arachnoid
• Subarachnoid Space:
  
  • Real Space__​
  • Space between arachnoid and pia
  • Filled with CSF
  • Arteries and veins

Question 4

What does the central nervous system consist of?

Answer 4

• Brain
• Spinal Cord

Question 5

What does the peripheral nervous system consist of?

Answer 5

• Cranial and spinal nerves

Question 6

Describe the composition of the spinal cord. What differentiates the components?

Answer 6

Gray Matter (inner)

• Neuronal cell bodies, dendrites, unmyelinated nerve cell processes

White Matter (outer)

• Myelinated axons (processes)

Question 7

What is the conus medullaris? Differentiate differences in cord length based upon age.

Answer 7

• End of the spinal cord
  
  • In embryo: spinal cord extends entire length of vertebral canal (vertebral column grows faster than the cord):
    
    • In infants: spinal cord typically ends at levels of L3 vertebra
    • In adults: spinal cord typically ends at inferior border of L1 vertebra

Question 8

What is the cauda equina?

Answer 8

• Inferior to the conus medullaris
• Nerve roots coming off of cord
• “Horse’s Tail”

Question 9

What is a lumbar puncture? Describe the location of a lumbar puncture and why this is important.

Answer 9

• Extract CSF for medical inspection
• Needle must be inserted below L1 (end of spinal cord in adults)
  
  • Usually between processes of L3 and L4 or L4 and L5
    
    • Utilize iliac crests (level of L4 spinous process)
    • In infants the cord ends at L3 (must perform below L4)

Question 10

Describe spinal nerves. How many pairs of spinal nerves are there?

Answer 10

• Nerves that come off the spinal cord
• 31 Pairs:
  
  • 8 Cervical (C1-C8)
    
    • C1-C7 exit superior to the body of respective vertebrae
    • C8 exits between C7 and T1
  • 12 Thoracic (T1-T12)
  • 5 Lumbar (L1-L5)
  • 5 Sacral (S1-S5)
  • 1 Coccygeal (COC1)
• Enter/Exit vertebral canal through intervertebral foramina
• Nerves exit inferior to the bodies of respective vertebrae

Question 11

Anterior (Ventral) Root

Answer 11

• Contains axons of motor neurons
• Cell bodies of motor neurons are in anterior/ventral horn of spinal cord

Question 12

Posterior (Dorsal) Root

Answer 12

• Contains axons of sensory neurons
• Cell bodies of sensory neurons are within the posterior/dorsal root ganglion (within intervertebral foramen)

Question 13

Spinal Nerve

Answer 13

• Formed when anterior and posterior roots unite
• Contains motor and sensory axons
• Exits via intervertebral foramen
• Splits into posterior and anterior rami

Question 14

Posterior Ramus

Answer 14

• Innervates skin of back and deep back muscles
  
  • C1 Posterior Ramus: Suboccipital n. (motor only; mm. of suboccipital triangle)
  • C2 Posterior Ramus: Greater Occipital n. (sensory only; sensation from scalp)
• Motor and Sensory

Question 15

Anteior Ramus

Answer 15

• Innervates everything other than skin of back/deep back muscles
• Motor and sensory

Question 16

Sympathetic Trunk Ganglion

Answer 16

• Connected to anterior ramus by rami communicantes

Question 17

Dermatomes

Answer 17

• Segments of skin innervated by a single spinal nerve
• Dermatomal Maps: show general patterns of dermatomes
• Beneficial for:
  
  • Pinpointing Specific Damage
  • Referred Pain

Question 18

Herpes Zoster

Answer 18

• Shingles
• Caused by varicella zoster (chicken pox) virus
• Virus remains dormant in posterior root ganglion
  
  • May reactivate and cause painful blistering along dermatomes

Question 19

Anterior Spinal Artery

Answer 19

• Supplies anterior 2/3 of superior spinal cord
• One

Question 20

Posterior Spinal Arteries

Answer 20

• Supply posterior 1/3 of superior spinal cord
• Two

Question 21

Radicular Arteries

Answer 21

• 26 of these
• Segmental arteries that branch from intercostal or lumbar arteries
• Supply inferior spinal cord
• One of these arteries is typically dominant

Question 22

Internal Vertebral Venous Plexus

Answer 22

• Network of veins within the vertebral canal
• Exists in epidural space

Question 23

External Vertebral Venous Plexus

Answer 23

• Around vertebrae
• Communicates with other plexus and nearby veins