A 50-year-old male patient presented with ataxia and gait abnormality along with fleeting and repetitive lancinating pains, primarily in the legs. He also complained of paresthesias and bladder disturbances. On neurological examination, Loss of reflexes in B/L lower limbs Romberg sign was present B/L Argyll Robeson pupils Impaired position and vibratory sense. MRI spine All the statements associated with the most impoant tract involved in the above disease are true except: –
Correct Answer: External arcuate fibres are the 2nd order neurons
Description: This is a case of Tabes dorsalis with involvement of the dorsal column. POSTERIOR COLUMN TRACT Axons enter the spinal cord from the posterior root ganglion. Pass directly to the posterior white column of the same side. Many of the long ascending fibers travel upward in the posterior white column as the fasciculus gracilis and fasciculus cuneatus. Then synapse on the second-order neurons in the nuclei gracilis and cuneatus of the medulla oblongata. The axons of the second- order neurons, called the internal arcuate fibers The fibers then ascend as a single compact bundle, the medial lemniscus The fibers terminate by synapsing on the third-order neurons in the ventral posterolateral nucleus of the thalamus. Axons of the third-order neuron leave and pass through the posterior limb of the internal capsule and corona radiata Ultimately reach the somesthetic area (AREAS 3,1,2) in the postcentral gyrus of the cerebral coex.
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