Spinal Cord

Question 1

What is the blood supply of the spinal cord?

Answer 1

1 anterior spinal artery
2 posterior spinal arteries

Question 2

What does the pia mater become at the end of the spinal cord?

Answer 2

Filum terminale- tethers SC to coccyx

Question 3

What does the extradural space in the SC contain?

Answer 3

Spinal nerve roots
Epidural venous plexus
Lymphatics
Loose connective tissue
Space where an epidural is administered

Question 4

How many spinal nerves are there?

Answer 4

31 pairs
8 Cervical
12 Throacic
5 lumbar
5 sacral
1 Coccygeal

Question 5

What does the grey matter of the spinal cord contain?

Answer 5

Neuronal cell nuclei
Demyelinated nerve fibres

Question 6

What does the white matter of the spinal cord contain?

Answer 6

Ascending & descending myelinated fibres

Question 7

Where do sensory neurones enter the spinal cord?

Answer 7

Dorsal horn
Synapse with interneurons in grey matter
Then synapse with motor nerves and emerge via ventral horn

Question 8

How is the anterior spinal artery formed?

Answer 8

Vertebral arteries meet at foramen magnum
Supplies ant 2/3 of spinal cord

Question 9

How is the posterior spinal arteries formed?

Answer 9

Branches of the posterior inferior cerebellar arteries
Supply posterior 1/3 spinal cord

Question 10

What is the supporting blood supply to the spinal cord called?

Answer 10

Radicular arteries
Artery of Adamkiewicz - branch of thoracolumbar aorta at L1

Question 11

How is the spinal cord perfusion pressure calculated?

Answer 11

SCPP = MAP - CSF pressure

Question 12

What is the impact of cross clamping the aorta?

Answer 12

Causes proximal HTN
Increases CSF pressure

Question 13

What are the 3 spinal veins?

Answer 13

3 anterior
3 posterior
Drain into anterior & posterior medullary & radicular veins

Question 14

Where does the filum terminale begin & end ?

Answer 14

Begin: Distal tip of conus medullaris
End: Inferior border of S2

Question 15

What are the major ascending pathways in the spinal cord?

Answer 15

SENSORY: Spinothalamic tract
Dorsal column

Question 16

What are the major descending pathways in the spinal cord?

Answer 16

MOTOR: Lateral corticospinal tract (AKA pyramidal tract)

Question 17

What fibres does the spinothalamic tract carry?

Answer 17

1st order neurones: Aδ and C fibres

Question 18

What does the spinothalamic tract sense?

Answer 18

• Nociception
• Crude touch
• Temperature
• Pressure

Question 19

Where do spinothalamic nerve fibres decussate?

Answer 19

At the level of the spinal cord and ascend as the lateral ST tract

Question 20

Where does the ST tract terminate?

Answer 20

3rd order neurones synapse in ventral posterolateral nucleus of the thalamus
Terminate in sensory area of post central gyrus

Question 21

What is the dorsal column the pathway for?

Answer 21

• Fine touch
• Conscious proprioception
• 2 point discrimination

Question 22

Where do DC fibres ascend?

Answer 22

Enter spinal cord via dorsal root ganglia
Ascend on ipsilateral side of fasciculus cuneatus & gracilis before synapsing in medulla

Question 23

Where does the DC terminate?

Answer 23

2nd order neurones synapse in ventral posterolateral nucleus of thalamus
3rd order neurones then terminate in post central gyrus of sensory cortex

Question 24

What is the corticospinal tract responsible for?

Answer 24

Voluntary motor control

Question 25

What is the pathway of the CS tract?

Answer 25

• 1st order originate in pyramidal cells in motor cortex
• Descend into medulla
• Enter spinal cord forming anterior/lateral CS tracts
• Axons synapse with internuncial neurones in anterior grey matter
• Synapse with lower motor neurones that innervate skeletal muscle

Question 26

Where do the CS tracts decussate?

Answer 26

80% decussate in the spinal cord immediately after leaving the medulla
20% continue down as anterior CS tracts