Neurology- Spinal Nerves/Cord Lesions/Reflexes Flashcards
How many spinal nerves are there?
31 pairs
8 cervical
12 thoracic
5 lumbar
5sacral
1 coccygeal
Nerves C1-C7 exist above the corresponding vertebra but since there are only 7 cervical vertebrae and 8 cervical nerves, Nerve C8 exits below vertebra C7 and all thoracic, lumbar, and sacral nerves exit below their respective vertebrae
What happens in vertebral disc herniation?
the nucleus pulposus (soft central disc) herniates through the annulus fibrosus
What is the most common spot for vertebral disc herniation?
posterolaterally at L4-L5 or L5-S1
Where does th spinal cord end caudually in adults?
L1-L2
The subarachnoid space (which contains the CSF) extends to the lower border of S2 vertebra and a LP is usually performed between L3-L4 or L4-L5 at the level of the cauda equina
Spinal cord and associated tracts pg 469


What does the dorsal column consist of? What does it do?

fasciculus gracilis (lower legs, and body)
fasciculus cuneatus (upper body and arms)
What does the lateral spinothalamic tract do?

part of the ascending pathways that relay pain and temperature sensory to the brain
What does the anterior spinothalamic tract do?
part of the ascending pathways that relay crude touch and pressure to the brain
What does the lateral and anterior corticospinal tracts do?
motor output as part of descending pathways
Again, the dorsal column is involved in ascending relay of pressure, vibration, fine touch, and proprioception. Describe the path of the dorsal column sensory relay?
1st order neuron: sensory nerve ending in the periphery with a cell body in the DRG that sends an axon into the spinal cord and ascends ipsilateraly in the dorsal column
synapse 1: ipslilateral nucleus cuneatus or graculus (medulla)
2nd order neuron: deccusates in medulla and ascends contralaterally in the medial meniscus
synapse 2: VPL (thalamus)
3rd order neuron: sensory cortex
Again, the spinothalamic tract is involved in ascending relay of pain and temp (lateral) and crude touch and pressure (anterior). Describe the path of the spintothalamic tract sensory relay?
1st order neuron: sensory nerve ending (Adelta and C fibers) with cell body in the DRG and enters the spinal cord
synapse 1: ipsilaterl gray matter in the spinal cord
2nd order neuron: decussates at the anterior white commissure and ascends contralaterally
synpase 2: VPL
3rd order neuron: sensory cortex
Again, the lateral corticospinal tract is involved in DEcending relay of voluntary movement of contralateral limbs. Describe this path.
1st order neuron: UMN with cell body in the primary motor cortex that descends ipsilaterally through the internal capsule. Most fibers decussate at the caudal medulla (pyramidal decussation) and descends contralaterally
synapse 1: cell body of anterior horn (spinal cord)
2nd order neuron: LMN leaves the spinal cord
synapse 2: NMJ
Weakness would be a sign of: UMN or LMN lesion?
both
Atrophy would be a sign of: UMN or LMN lesion?
LMN
Fasciculations would be a sign of: UMN or LMN lesion?
LMN
How are reflexes and tone affected by UMN or LMN lesions?
UMN: both increased
LMN: both decreased
A positive Babinski sign, clasp knife spasticity, and spastic paralysis would be a sign of: UMN or LMN lesion?
UMN only
NOTE: a positive Babinskin sign is normal in infants
Flacid paralysis would be a sign of: UMN or LMN lesion?
LMN only
What diseases are caused by disease of the anterior horns?
poliomyelitis and spinal muscular atrophy (Werdnig-Hoffmann disease)
LMN lesions only; flaccid paralysis
What is poliomyelitis?
Poliomyelitis, often called polio or infantile paralysis, is an infectious disease caused by the poliovirus. In about 0.5% of cases there is muscle weakness resulting in an inability to move.[1] This can occur over a few hours to few days.[1][2] The weakness most often involves the legs but may less commonly involve the muscles of the head, neck and diaphragm.
Many but not all people fully recover. In those with muscle weakness about 2% to 5% of children and 15% to 30% of adults die. Another 25% of people have minor symptoms such as fever and a sore throat and up to 5% have headache, neck stiffness and pains in the arms and legs. These people are usually back to normal within one or two weeks.
In up to 70% of infections there are no symptoms.
Years after recovery post-polio syndrome may occur, with a slow development of muscle weakness similar to that which the person had during the initial infection
What causes MS?
demyelination of mostly white matters in the cervical region
Disease of the dorsal columns causes/or is caused by what diseases?
tabes dorsalis
can be caused by vitamin B12 deficiency
What is tabes dorsalis?
a sequelae of teritary syphillis resulting from demyelination of the dorsal columns and roote causing impaired sensation and proprioception, and progressive sensory ataxia (inability to sense or feel the legs leading to poor coordination)
How is poliovirus spread?
fecal - oral











