Sensory systems I Flashcards
the DC-ML pathway relays what modalities?
crude and discriminative touch, stereognosis, flutter-vibratory, general proprioception
what type of fibers make up the first order neuron in the DC-ML pathway?
large diameter, heavily myelinated Aa and AB fibers
where is the cell body for first order neurons of the DC-ML pathway?
DRG
Where is the FC present? FG?
- FC = C1-T6 2. FG = all spinal cord levels
where is the cell body of the second order neuron in the DC-ML pathway located?
NG or NC
what is the sensory decussation of the DC-ML pathway?
crossing of the internal arcuate fibers (axons from second order neurons) across the midline to form the medial lemniscus
what forms the medial lemniscus?
gathering of the internal arcuate fibers (axons of second order neurons)
where does the medial lemniscus go?
ascends to ventral posterior lateral (VPL) nucleus of the thalamus to synapse with third order neurons
where is the cell body of the third order neuron of the DC-ML pathway located?
VPL nucleus of the thalamus
where do the axons of the third order neurons go?
exit thalamus and ascend through the posterior limb of he internal capsule to terminate in the postcentral gyrus (Brodman’s areas 3, 1, 2, 3a, 3b)primary somatosensory cortex (parietal lobe)
when is sensory information consciously perceived?
when it enters the primary somatosensory cortex
where does information go after entering the primary somatosensory cortex?
sensory association cortex
what is Rhomberg’s sign?
loss or impairment of conscious proprioception, difficulty maintaining balance when eyes are closed and standing with feet close together
tabes dorsalis (neurosyphilis) is characterized by what signs?
- damage to DRGs or large diameter heavily myelinated axons in dorsal columns 2. sensory ataxia 3. Rhomberg’s sign
what artery supplies the medial surface of the parietal lobe LL area?
anterior cerebral