Spinal Cord Flashcards
What is the blood supply of the spinal cord?
1 anterior spinal artery
2 posterior spinal arteries
What does the pia mater become at the end of the spinal cord?
Filum terminale- tethers SC to coccyx
What does the extradural space in the SC contain?
Spinal nerve roots
Epidural venous plexus
Lymphatics
Loose connective tissue
Space where an epidural is administered
How many spinal nerves are there?
31 pairs
8 Cervical
12 Throacic
5 lumbar
5 sacral
1 Coccygeal
What does the grey matter of the spinal cord contain?
Neuronal cell nuclei
Demyelinated nerve fibres
What does the white matter of the spinal cord contain?
Ascending & descending myelinated fibres
Where do sensory neurones enter the spinal cord?
Dorsal horn
Synapse with interneurons in grey matter
Then synapse with motor nerves and emerge via ventral horn
How is the anterior spinal artery formed?
Vertebral arteries meet at foramen magnum
Supplies ant 2/3 of spinal cord
How is the posterior spinal arteries formed?
Branches of the posterior inferior cerebellar arteries
Supply posterior 1/3 spinal cord
What is the supporting blood supply to the spinal cord called?
Radicular arteries
Artery of Adamkiewicz - branch of thoracolumbar aorta at L1
How is the spinal cord perfusion pressure calculated?
SCPP = MAP - CSF pressure
What is the impact of cross clamping the aorta?
Causes proximal HTN
Increases CSF pressure
What are the 3 spinal veins?
3 anterior
3 posterior
Drain into anterior & posterior medullary & radicular veins
Where does the filum terminale begin & end ?
Begin: Distal tip of conus medullaris
End: Inferior border of S2
What are the major ascending pathways in the spinal cord?
SENSORY: Spinothalamic tract
Dorsal column
What are the major descending pathways in the spinal cord?
MOTOR: Lateral corticospinal tract (AKA pyramidal tract)
What fibres does the spinothalamic tract carry?
1st order neurones: Aδ and C fibres
What does the spinothalamic tract sense?
- Nociception
- Crude touch
- Temperature
- Pressure
Where do spinothalamic nerve fibres decussate?
At the level of the spinal cord and ascend as the lateral ST tract
Where does the ST tract terminate?
3rd order neurones synapse in ventral posterolateral nucleus of the thalamus
Terminate in sensory area of post central gyrus
What is the dorsal column the pathway for?
- Fine touch
- Conscious proprioception
- 2 point discrimination
Where do DC fibres ascend?
Enter spinal cord via dorsal root ganglia
Ascend on ipsilateral side of fasciculus cuneatus & gracilis before synapsing in medulla
Where does the DC terminate?
2nd order neurones synapse in ventral posterolateral nucleus of thalamus
3rd order neurones then terminate in post central gyrus of sensory cortex
What is the corticospinal tract responsible for?
Voluntary motor control
What is the pathway of the CS tract?
- 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
Where do the CS tracts decussate?
80% decussate in the spinal cord immediately after leaving the medulla
20% continue down as anterior CS tracts
