Topic 10 - Spinal cord

Question 1

Describe the procedure and used of epidural injections

Answer 1

• Injection into epidural space, doesn’t penetrate the meninges
• Done at L3/4 or L4/5 vertebral level
• Used to administer analgesia - block sensory fibres to prevent pain

Question 2

Describe the structure of the coccyx

Answer 2

• Articulates w/ apex of sacrum
• Lack of vertebral arch - no spinal cord

Question 3

Where is the supracristal line?

Answer 3

At the level of the iliac crest, marks the location of L4

Question 4

Describe the venous drainage of the spinal cord

Answer 4

• 3 anterior and 3 posterior spinal veins - valveless, form anastomosing network on surface of spinal cord + radicular veins
  
  • Drain into internal and external venous plexus, which drain to the systemic segmental veins
  • Internal vertebral plexus drain to dural venous sinuses superiorly
• Epidural space contains Baston’s veins/plexus
• Also subarachnoid veins
• Veins exit at segmental levels

Question 5

Describe the structural features of thoracic vertebrae

Answer 5

• Articulate with ribs
• Spinous processes point inferiorly + posteriorly

Question 6

Describe the arterial supply of the spinal cord

Answer 6

• 3 longitudinal arteries
  
  • Anterior spinal arteries - from branches of vertebral arteries, run in anterior median fissure
  • 2 posterior spinal arteries - from vertebral or posteroinferior cerebellar arteries, anastomose in pia
• • anterior and posterior segmental medullary arteries - small vessels, enter with nerve roots
    
    • Largest anterior segmental medullary artey = artery of Adamkiewicz (from inferior intercostal or upper lumber arteries, supplies inferior 2/3 of spinal cord)

Question 7

How are the cervical and lumbar spinal segments structurally distinct? Why?

Answer 7

Have large ventral and dorsal horns - innervate limbs so need high sensory and motor output

Question 8

Describe the segmentation of the spinal cord

Answer 8

• 8 cervical
• 12 thoracic
• 5 lumbar
• 5 sacral
• 1 coccygeal

Question 9

Describe the clinical significance of the lumbar cistern

Answer 9

Site for epidural injections and lumbar punctures

Question 10

Describe the structure of intravertebral discs

Answer 10

• Fibrocartilaginous cylinder, between vertebrae
• Allows flexibility of spine, acts as shock absorber
• Wedge shaped in lumbar and thoracic
• Two parts - nucleus pulposus (gelatinous) and annulus fibrosis (tough, collagenous, surrounds nucleus pulposus)

Question 11

Describe the arrangement of the vertebrae in the vertebral column

Answer 11

33 vertebrae separated by intravertebral discs

• 7 cervical
• 12 thoracic
• 5 lumbar
• 5 (fused) sacral
• 4 (fused) coccygeal

Question 12

Describe the curvature of the spine

Answer 12

• Cervical lordosis
• Thoracic kyphosis
• Lumbar lordosis
• Sacral kyphosis

Question 13

Describe the clinical importance of the anterior spinal artery

Answer 13

Anterior spinal artery syndrome - loss of urinary and/or faecal continence, impaired motor function in legs/spasticity

Question 14

Describe the procedure and use of lumbar punctures

Answer 14

• Penetrates dura to access CSF
• Diagnostic - withdraw and test CSF or test pressure of CSF
• Therapeutic - antibiotic administration, route for chemotherapy
• L3/4 or L4/5 vertebral level - cauda equina won’t be damaged

Question 15

Describe the beginning and end of the spinal cord

Answer 15

• Begins as continuation of medulla oblongata, ends at conus medullaris
• Becomes cauda equina
• Cord terminates at L3/4 in newborns, L1/2 in adults - vertebral column lengthens more than spinal cord during development

Question 16

Describe the arrangement of white and grey matter in the spinal cord

Answer 16

• Inner grey matter
  
  • Dorsal horn (sensory)
  • Intermediate horn
  • Ventral horn (motor)
• Outer white matter
  
  • Dorsal funiculus
  • Lateral funiculus
  • Ventral funiculus

Question 17

List the ligaments of the vertebral column

Answer 17

• Anterior and posterior longitudinal ligament (run full length of vertebral column)
• Ligamentum flavum
• Interspinous/supraspinous ligaments
• Intertrasverse ligaments

Question 18

What is the role of the filum terminale?

Answer 18

Fibrous tissue which extends from conus medullaris to sacrum - stops movement of the cauda equina

Question 19

What is the clinical significance of Baston’s plexus?

Answer 19

• Anastomose closely with venous drainage of abdominal/pelvic organs
• Major route of spread of cancer from deep pelvic regions
• Valveless

Question 20

Describe the structural features of sacral vertebrae

Answer 20

Fused, facets for articulations w/ pelvis at sacroiliac joint

Question 21

Describe the structural features of lumbar vertebrae

Answer 21

• Largest - big bodies for weight bearing
• Short spinous body - point less inferiorly

Question 22

Describe the origins and path of spinal nerves

Answer 22

• Each spinal cord segment gives rise to 2 spinal nerves - L and R
• C1-7 pass through their intervertebral foramen above the level of the corresponding vertebral body
• C8 onwards exit below the level of the vertebral body

Question 23

Describe the structure of vertebrae

Answer 23

• Anterior vertebral body
  
  • Weight bearing
  • Lined by hyaline cartilage
  • Separated by IVD
• Posterior vertebral arch
  
  • Forms vertebral foramen, line up to give vertebral canal which spinal cord travels through
  • Spinous processes - posterior
  • Transverse processes - in thoracic articulate with ribs
  • Articular processes - join one vertebra to its corresponding vertebrae superiorly/inferiorly

Question 24

Describe the structural features of cervical vertebrae

Answer 24

• C2-C6/7 spinous processes bifurcate
• Transverse foramina transmit vertebral arteries to brain
• C1/2 are unique (atlas/axis) - odontoid peg