MODULE 5
THE CORTICO-RETICULO-SPINAL PATHWAY
This is the third and last pathway from the cortex to the spinal cord that we will consider. It originates, at the cortical level, in a region somewhat anterior to the central sulcus, where axial muscles (the trunk of the body) and muscles controlling the proximal parts of the extremities are represented (Figure 5-1). The pathway descends through the internal capsule, along with the corticospinal tract and the cortico-rubro-spinal pathway. At the midbrain level, the fibers move dorsally to descend diffusely through the reticular formation of the brainstem. They end in the reticular formation of the medulla and pons. Blumenfeld shows the reticulospinal part of this pathway in his Figure 6.11E and Haines does the same in his Figure 24-9. Neither author includes the cortical input to the reticular formation, but Haines mentions it and it is an essential part of the Lawrence-Kuypers hypothesis Figure 5-1.
This is not a pathway that we can identify on slides. We have drawn it in on the sections that follow just to give you a rough idea of the plan. You can call them up using Figure 5-15.
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