Point 3











Wire Diagram - Voluntary Control of MusclesClinicians will rarely talk about the deficits resulting from a lesion of the DSCT. Lesions in the spinal cord usually damage other tracts that camouflage such deficits. (One of these pathways lies right next to the DSCT and we will talk about it next!). But if we think about the information this tract is carrying we can see that such a lesion would result in a loss of information regarding the constant and changing lengths of muscle and tension on muscles. This information is going to the cerebellum and we are not really aware of it as we fish, ice skate, shoot buckets, bike through the arboretum, or start our backswing at the Ridge. This information tells the cerebellum about how long each muscle is, how fast each muscle is moving and how much tension is on each muscle. (#2 above) The cerebellum then can compare this ascending information regarding what the muscles are doing with other information (the sources of which we will learn later) regarding what higher motor centers want the muscles to do. (#1 above) Then a correction can occur via pathways that leave the cerebellum to influence motor performance (#3 above). Whew!!

For our problem solving, let's equate a lesion of the DSCT with loss of unconscious proprioception and incoordination or ataxia. This incoordination deficit will be IPSILATERAL to the lesion because there is no crossing of information in the spinal cord. The DSCT is IPSI to the receptors. Also, the cerebellum influences (via several output pathways) the same or ipsilateral side of the body. Think about the dorsal column system. Is there crossing from the receptors to the fasc. gracilis and fasc. cuneatus in the spinal cord?? How about the pain and temperature pathways?