The differences in the anatomy of the thoracolumbar and sacral autonomic outflow are quantitative

Abstract

Purpose We have re-evaluated the anatomical arguments that underlie the division of the spinal visceral outflow into sympathetic and parasympathetic divisions. Methodology Using a systematic literature search, we mapped the location of catecholaminergic neurons throughout the mammalian peripheral nervous system. Subsequently, a narrative method was employed to characterize segment-dependent differences in the location of preganglionic cell bodies and the composition of white and gray rami communicantes. Results and Conclusion One hundred seventy studies were included in the systematic review, providing information on 389 anatomical structures. Catecholaminergic nerve fibers are present in most spinal and all cranial nerves and ganglia, including those that are known for their parasympathetic function. Along the entire spinal autonomic outflow pathways, proximal and distal catecholaminergic cell bodies are common in the head, thoracic, and abdominal and pelvic region, which invalidates the “short-versus-long preganglionic neuron” argument. Contrary to the classically confined outflow levels T1-L2 and S2-S4, preganglionic neurons have been found in the resulting lumbar gap. Preganglionic cell bodies that are located in the intermediolateral zone of the thoracolumbar spinal cord gradually nest more ventrally within the ventral motor nuclei at the lumbar and sacral levels, and their fibers bypass the white ramus communicans and sympathetic trunk to emerge directly from the spinal roots. Bypassing the sympathetic trunk, therefore, is not exclusive for the sacral outflow. We conclude that the autonomic outflow displays a conserved architecture along the entire spinal axis, and that the perceived differences in the anatomy of the autonomic thoracolumbar and sacral outflow are quantitative.

Anatomical Location of the Vesical Branches of the Inferior Hypogastric Plexus in Human Cadavers

“…One limitation of this study is that pelvic ganglia were stained only with hematoxylin and eosin, or Luxol blue. Future studies should also consider immunohistochemical assays using antibodies that recognize markers of the sympathetic, parasympathetic, and sensory nervous system to further describe the character of the human pelvic ganglion, as previously completed [49][50][51][52][53]. Another limitation is that we used only the ureteral orifice, ureter, and bladder as landmarks for identification and localization of the vesical nerve branches.…”