MODULE 3
INTRODUCTION
- - Once again, we have a module with two objectives. The first is simply to trace the dorsal column-medial lemniscus (DC-ML) pathway as it ascends from the spinal cord, through the brainstem to reach the thalamus, and then, the cerebral cortex. But to do this you will have to travel through new, uncharted territory. Think of it as though you are taking your first cross-country trip, driving from New York to Los Angeles. Your main goal is just to get there. But, you are going to pass by a lot of interesting things along the way - the Grand Canyon, for example. It would be foolish not to take a look, even though these sites have nothing to do with getting to your destination. And the more familiar you are with them, the less likely you are to get lost, the next time you make the trip. So, our second objective is to introduce you to some of the sites within the brainstem. While you would only have to look at three or four slides to get a good idea of how the DC-ML pathway ascends through the spinal cord and brain, we urge you to look at most of them and begin to notice structures that lie nearby. These relationships can have clinical significance, as we shall see in a few days.
- - Be aware that all three of our prime reference texts - Blumenfeld, Fitzgerald and Haines - refer to this as the posterior column-medial lemniscus pathway (PC-ML). It is an open question whether to use the terms "anterior-posterior" or "dorsal-ventral" when describing spinal cord structures. Blumenfeld, for example, talks about the "posterior column-medial lemniscus pathway", but also describes "dorsal roots" and "ventral roots".
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