A 58 year old male who is a known case of diabetes mellitus , hypeensionn and hypercholesterolemis presented with loss of sensation below the level of the umbilicus. There is no motor loss. His bowel and bladder function is intact. MRI scan revealed spinal infarction affecting the posterior white columns in the tenth thoracic segment of the spinal cord. Which of the following sensations would be intact in this patient.
Correct Answer: Pain
Description: The dorsal column/posterior white column doesnt carry the pain sensation, hence it would be intact. The pain and temperature sensations are carried by the lateral spinothalamic tract. Pathway Dorsal Column Anterior spinothalamic tract Lateral spinothalamic tract Receptor Meissner corpuscles, pacinian corpuscles, muscle spiindles, golgi tendon organs Free nerve endings Free nerve endings First order neurons First order neurons from the receptors enter spinal cord for the dorsal root > ascend ipsilsterally as fasciculus gracilis and fasciculus cuneatus > synapse in nucleus gracilic and nucleus cuneatus in medulla > First order neurons from the dorsal root ganglion ascend for a few segments and synapse with the cells in the posterior gray column> -do- Second order neurons Second order neurons from nucleus gracilis and nucleus cuneatus continue as internal arcuate fibers > deccusate in the lower medulla and ascennds as medial leminiscus on the contralateral side > synapse in the ventral posterolateral nucleus of the thalamus Second order neurons from the posterior gray column crossover to the opposite side and ascend as anterior and lateral spinothalamic tract> form the spinal lemniscus in the medulla> ascend through pons and synapses in the ventro posterolateral and nucleus of thalamus > -do- Third order neurons Third order neuron from the ventral posterolateral nucleus of thalamus ascend in the posterior limb of internal capsule and corona radiata and terminte in somatosensory coex Third order neurons from the ventral posterolateral nucleus of thalamus ascend through the posterior limb of internal capsule and corona radiata and terminate in the somatosensory coex -do- Decussation Medulla Spinal cord-few segments above the entry point Spinal cord onne segment above the entry point Sensations carried Proprioception, crue touch, pressure, vibration, position sense Light touch, pressure Pain and temperature Ref: Snell's Clinical Neuroanatomy 8th edition PGno: 143
Category:
Anatomy
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