Рет қаралды 356
This video presents the pathway of touch and proprioception.
- 1st order neuron ascends in the same side of spinal cord (Dorsal column) and medullar as gracil and cuneat tracts until it ends in gracil and cuneate nuclei. Gracil tract is medial and carrying sensation from lower half of the body while cuneate tract is lateral and carries sensation from upper half of the body.
- 2nd order neuron, crosses to the opposite side, ascends through brainstem as medial lemniscus until it ends in PVL nucleus of thalamus
- 3rd order neuron, projects from thalamus to the cerebral cortex (upper part of postcentral gyrus and paracentral lobule).
Injury of Dorsal column or gracil and cuneate tracts causes ipsilateral loss of proprioception
Injury of medial lemniscus (2nd order neuron) or 3rd order neuron causes contralateral loss of proprioception.
Loss of proprioception causes disturbed balance, astergnosis (inability to recognize an object by touch while the eye is closed), also loss of two points discrimination.