Spinal Cord Function and Dysfunction Flashcards
What are the two enlargements in the spinal cord and what is their significance?
Cervical enlargement (C3-T1) – has extra motor neurons that go to the muscles of the upper limb Lumbosacral enlargement (L1-S3) – has extra motor neurons that go to the muscles of the lower limb
What are the little protrusion of pia mater around the spinal cord called?
Denticulate ligaments
Which space is present in the spinal meninges but not in the cranial meninges?
Epidural space – this can be used for injecting anaesthetics (below L4 is safest ) (note can do nerve block at L3 into dura mater-1 level deeper than epi)
What are the three most important tracts in spinal cord injury? State their roles.
Lateral corticospinal tract – fine motor movements
Dorsal columns – touch, pressure, vibration, proprioception
Spinothalamic tract – pain and temperature
What are the two stages of lateral corticospinal tract damage?
SPINAL SHOCK – you get loss of reflexes below the level of the lesion leading to flaccid paralysis. The limbs become floppy and there is little muscle tone
RETURN OF REFLEXES – you get hyperreflexia and spasticity. The patient experiences spontaneous muscle contraction and there is very high muscle tone – rigid paralysis
Where do the upper motor neurons within the lateral corticospinal tract decussate?
Pyramidal decussation in the medulla
If you have a unilateral lesion of the lateral corticospinal tract in the mid-thoracic region, where will the deficit be?
Ipsilateral – on the same side as the lesion because the fibres decussate at the pyramidal decussation in the medulla
Where do the sensory fibres of the dorsal columns decussate?
Sensory decussation in the medulla
How are pain neurons arranged differently to other sensory and motor neurons?
The first order neurons synapse in the dorsal horn and then the second order neuron crosses to the contralateral side immediately (at the level of the synapse with the first order neurone) The second order neurons then ascend on the contralateral side
What is syringomyelia? Describe and explain its features.
Enlargement of the central canal (the space is called a syrinx)
This selectively affects the spinothalamic fibres that are crossing at the level of the lesion and it does not affect fibres that have alreadycrossed
So if the enlargement of the central canal is in the region of the cervical enlargement, you could get loss of pain/temperature sensation in the arms but not the legs (because those fibres would already have crossed and would be ascending in the spinothalamic tract away from the central canal)
what is the function of the cells in the ventral, dorsal and intermediate horns of the spinal cord
dorsal horn: The neurons of the dorsal horns receive sensory information ventral horn: sends out motor fibres to muscles lateral horn: at T6: sympathetic viceromotor at s6 parasympathetic viceromotor
what is brown-sequard syndrome
Brown-Sequard syndrome (BSS) is a rare neurological condition characterized by a lesion in half the spinal cord which results in weakness or paralysis (hemiparaplegia) a loss of sensation (hemianesthesia) on the same side and loss of pain/temp in the contralateral side.
what are the main areas of grey matter on a spinal cord cross section
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whats the difference between a nerve, nerve root and ramus
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whats the difference between spinal and brain meninges
epidural space and denticulate ligaments (extension of pia into dura)
what are the main descending tracts
Lateral corticospinal tract (from contralateral cortex (mostly limbs))
anterior corticospinal tract (from ipsilateral cortex (mostly axial aka trunk))
what are the main ascending tracts
Dorsal column-Discriminative touch, vibration, proprioception:
-gracile (from ipsilateral lower limb)and Cuneate (from ipsilateral upper limb) fasciculi
Spinothalamic tract: pain and temp from contralater side
