Neuroanatomy and basics Flashcards
Describe features of an UMN lesion
Increased tone, power, reflexes
Upgoing plantars + Babinksi sign = dorsiflexion of the big toe instead of curling your feet down as though to hold onto a branch
Describe features of an LMN lesion
Reduced tone, power and reflexes
Muscle wasting
Fasciculations
What are the two components of the sensory pathway?
Dorsal column medial lemniscus pathway (DCML)
Spinothalamic
What does the dorsal column medial lemniscus pathway contain?
Fine touch, two point discrimination, proprioception
Which sensations does the spinothalamic pathway take?
Temperature and pain
Describe the spinothalamic pathway
This one needs to get to the brain QUICK
so instead of decussating in the brain, it quickly hops lanes in the spinal cord itself, and travels CONTRALATERALLY
First order neuron - synapses at spinal cord
Second order neuron - synapses at thalamus
Third order neuron - thalamus to the somatosensory cortex
Describe the dorsal column medial lemniscus pathway
This one can takes its time so it travels ipsilaterally and first synapses at the MEDULLA, where it CROSSES OVER
and then from the contralateral medulla to the THALAMUS
and then from the thalamus to the somatosensory cortex
Where does the decussation happen for the dorsal medial lemniscus pathway?
AT the medulla
Where does the decussation happen in the spinothalamic tract?
In the spinal cord
Describe the pathological findings if there is a lesion on the right hand side
Lesion side = side where you lose ipsilateral FINE TOUCH (DCML pathway)
at the contralateral side, below the level of the lesion you would lose pain and temperature.
Essentially:
If there is loss of pain and temp on one side, it’s the other side that’s had the lesion.
If there’s loss of fine touch on one side, that’s the side that has the lesion.
Describe the innervation of the facial nerve and the resulting palsies.
There is a nucleus from which the facial nerve arises.
This nucleus is dually innervated from both sides of the brain.
Therefore a lesion above the nucleus on one side of the brain would still mean that this nucleus (and thus the facial nerve) is innervated by the other side of the brain joining this nucleus.
Whereas if there was a lesion below the nucleus, you would get complete lack of innervation to the areas of the face covered by the facial nerve.
What is Bell’s palsy?
LMN lesion of facial nerve
Sudden facial drooping
Inability to close eyelid
Inability to raise eyebrows
Inability to puff out cheeks
Post-auricular pain
Hyperacusis (pain at sounds, feeling like sounds are too loud)
Altered taste
Dry eyes
Forehead NOT spared
What does a UMN lesion of the face look like
UMN lesion - forehead sparing
Causes of Bell’s palsy
Due to inflammation and swelling of the facial nerve
How would you investigate for Bell’s palsy
Serology (borrelia, VZV)
MRI (SOL, stroke, MS)
LP
