what three pathways comprise the antero-lateral pathway?
- spino-thalamic tract
- spino-reticular tract
- spino-mesencephalic tract
where do antero-lateral 1SNs synapse to 2SNs
dorsal horn of the grey matter
where do antero-lateral tracts decussate?
immediately as they ascend, and take a few levels to completely cross
where do antero-lateral 2SNs synapse to 3SNs
thalamus
describe the somatotopic organization of the antero-lateral pathway
- opposite of PCML
- legs are most lateral, then trunk, arm, neck
what is contained within the thalamus?
- many relay nuclei
- cell bodies for third-order sensory neurons
define negative symptoms
loss of typical sensory abilities
define positive symptoms
new onset presence of abnormal sensation
what are negative symptoms of the PCML pathway?
- loss of proprioception and vibration
- loss of two-point discrimination
- astereognosis (recognition by touch)
- sensory ataxia (unsteady gait, uncoordinated movements, worse without vision)
describe a tabetic gait pattern
- high stepping
- foot flapping
- unsteadiness
what are negative symptoms of the antero-lateral pathway?
- loss of pain and temperature sensation
- reduced touch sensation
what are the positive symptoms of the PCML pathway?
tingling, numb sensations
what are the positive symptoms of the anterolateral pathway?
sharp, burning, or searing pain
define parathesia
abnormal, but not painful sensations
define hyperpathia/allodynia
painful sensations
what are symptoms of primary sensory neuron damage?
- radicular pain
- numbness and tingling throughout dermatome
- loss of deep tendon reflexes
what nerve takes sensory input from the face?
trigeminal nerve (CN V)
where are the cell bodies for CN V co-located?
Meckel’s cave
what sensory input goes to the mesencephalic trigeminal nucleus?
proprioception
what sensory input goes to the chief trigeminal sensory nucleus?
- fine touch
- dental pressure
what sensory input goes to the spinal trigeminal nucleus?
crude touch, pain, temperature
on what side do facial 1SNs synapse to 2SNs
ipsilateral
where do facial 2SNs project?
contralateral thalamus
