Anatomy of the Descending Pathways

Abstract

The sections in this article are: 1 Anatomical Techniques 1.1 Visualization of Neurons and Their Processes 1.1.1 Light Microscopy 1.1.2 Electron Microscopy 1.2 Tracing of Axons and Identification of Their Terminals by Techniques of Anterograde Labeling 1.2.1 Anterograde Degeneration Labeling 1.2.2 Anterograde Transport Labeling 1.2.3 Orthodromic Electrical Stimulation 1.3 Identification of Cells of Origin of Fiber Systems by Retrograde Labeling 1.3.1 Retrograde Degeneration Labeling 1.3.2 Retrograde Transport Labeling 1.3.3 Antidromic Electrical Stimulation 1.4 Identification of Neurons and Tracing of Their Axons 1.4.1 Histofluorescence 1.4.2 Immunohistochemistry 2 Anatomy of Spinal Cord and Brain Stem 2.1 Spinal Cord 2.1.1 Dorsal Horn 2.1.2 Somatic Motoneuronal Cell Groups 2.1.3 Autonomic Preganglionic Motoneuronal Cell Groups 2.1.4 Intermediate Zone 2.2 Brain Stem 2.2.1 Lower Brain Stem 2.2.2 Mesencephalon 2.2.3 Monoaminergic Neurons 3 Descending Pathways 3.1 Descending Brain Stem Pathways 3.1.1 Cells of Origin 3.1.2 Trajectory and Terminal Distribution 3.2 Descending Cortical Pathways 3.2.1 Corticospinal and Corticobulbar Pathways 3.2.2 Cortical Projections to Cell Groups of Descending Brain Stem Pathways 3.2.3 Laminar Distribution of Cortical Neurons Projecting to Subcortical and Spinal Structures 4 Synthesis 4.1 Grouping of Descending Pathways on the Basis of Their Terminal Distribution 4.1.1 Descending Brain Stem Pathways 4.1.2 Corticobulbar and Corticospinal Pathways 4.2 Functional Epilogue 4.2.1 Conclusion