45. SC Anatomy

Question 1

What are the 3 arteries that supply the spinal column? Which are paired?

Answer 1

Anterior Spinal Artery (unpaired) - arises from vertebral arteries - supplies ant 2/3 SC

Posterior Spinal Artery (Paired) - arises from PICA or vertebral arteries - supplies post 1/3 SC

Radicular Artery: from aorta, additional SC supply

Question 2

Damage to LMN vs damage to UMN

Answer 2

LMN: no reflex - flaccid paralysis
UMN: hyperreflexivity - spastic paralysis

Question 3

What are the main Descending SC tracts? (2 classes, 5 total)

Answer 3

Pyramidal Tracts

1. CS Tract - voluntary control of limb and body (lateral CS: larger, limb movement; anterior CS: smaller, trunk movement)
2. Corticobulbar tract - facial expression, mastication, swallowing

Extrapyramidal Tracts

1. Rubrospinal - fine arm movements
2. Reticulospinal/Vestibulospinal - postural/complex movement organization

Question 4

What are the 3 main ascending SC tracts?

Answer 4

Posterior Column, Dorsal Column Medial Lemniscal Pathway (Fasciculi Gracilis - legs, Fasciculi Cuneatus - arms) - vibration/deep touch/2 pt discrimination/proprioception

Spinocerebellar Tract: whole limb movements, postural adjustments to cerrebellum

Spinothalamic Tract: pain, temp, non-discriminative touch to primary sensory cortex

Question 5

Pathway of CS Tract: Lateral vs. Anterior

Answer 5

Lateral CS:
1 - cerebral cortex, decussation in medullary pyramids, descend SC ipsilaterally, synapse in ventral horn
2 - ventral horn - spinal nerve - muscle (limbs)

Anterior CS:
1 - cerebral cortex, descends SC contralaterally, decussation via ant. white commissures, synapse in ventral horn
2 - ventral horn - spinal nerve - muscle (trunk)

Question 6

Pathways of Dorsal Column-Medial Lemniscal Path vs. Spinothalamic Tract (AL System)
Where does it decussate?

Answer 6

DC-ML
1 - receptor afferent - dorsal root ganglion - dorsal horn, ascends SC ipsilaterally, synapse in nucleus cuneatus/gracilus
2 - decussates in medulla to thalamus

STT
1 - receptor afferent - dorsal root ganglion - dorsal horn, synapse
2 - decussates 1-3 levels where enters, ascends contralaterally to thalamus

Question 7

Complete Cord Transection (Sx)

Answer 7

Loss of All tracts below lesion bilaterally

No pain/temp, touch/proprioception, motor

Question 8

Posterior Column Syndrome
(What it is, what happens if unilateral?)

What is Tabes Dorsalis?

Answer 8

Damage to Dorsal Column (touch, proprio)
Loss of ipsilateral touch/proprio if unilateral

Tabes Dorsalis: degeneration of posterior columns in long-standing syphilis (neurosyphilis) - no proprioception = foot slapping gait

Question 9

Anterior Cord Syndrome

what it is, sx

Answer 9

Damage/occlusion to unpaired ant spinal artery
Lose everything except posterior column
Loss of motor fx bilaterally below lesion
Loss of pain/temp bilaterally below lesion

Question 10

Brown-Sequard Syndrome

what it is, sx

Answer 10

Damage to one side of sx
Loss of motor fx ipsilaterally
Loss of touch/proprio ipsilaterally
Loss of pain/temp contralaterally 1-3 segments below lesion

Question 11

Central Cord Syndrome

what it is, sx

Answer 11

Most common incomplete SC damage
Lose central tracts (Cervical info is medial, sacral info is lateral)

Loss of motor fx of chest and arms

Question 12

Traumatic SCI: difference between tetraplegia/quadriplegia and paraplegia

Answer 12

T/Q: impairment or loss of motor and/or sensory fx in cervical segments = impaired fx of arms, trunk, legs, pelvic organs

P: impaired/loss of motor and/or sensory fx in thoracic, lumbar, or sacral segments (spares arm)