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Anatomy
Published in Michael Stolberg, Gabrielle Falloppia, 1522/23–1562, 2023
Perhaps the most famous fallacy of Galen’s anatomy which arose from the fact that he based his account on the dissection of animals was his account of a rete mirabile at the base of the human brain. This rete mirabile, a conglomerate of arterial and venous vessels, is found in various vertebrate animals but not in humans. Falloppia not only explained to his students that the rete mirabile or plexus retiformis, as he also called it, did not occur in humans but was an “exquisite” part in horses and cattle. He also explained why they had a rete mirabile and man did not. When horses were exercising and running or cattle pulling carts or ploughs, they got hot and much venous and arterial blood ascended toward the head where it usually got mixed with the air inhaled through the nose to make animal spirit. When the arterial blood arrived in too large a quantity and very suddenly at the head, however, it could suffocate the animal spirit. Therefore, nature made this plexus reticularis, which could accommodate a lot of blood in its numerous and convoluted vessels and softened the impact of the blood on the cerebral ventricles.212
Microvascular Architecture and Networks
Published in John H. Barker, Gary L. Anderson, Michael D. Menger, Clinically Applied Microcirculation Research, 2019
As a result of the existence of such architectural features, the topological characteristics of microvascular networks may differ substantially. The topological analysis of such networks can be performed by using different ordering schemes, among which the so-called Horton-Strahler scheme6,13,18,21 and the generation scheme15 are the most widely used (Figure 6). While both schemes permit a quantifiable assessment of the architecture of interest, the generation scheme, which was introduced for the analysis of the airway system of the lung,20 is generally more useful for hemodynamic modeling purposes. However, it cannot without additional modifications be applied to systems exhibiting arterio-arterial connections (arcade systems), and substantial limitations also result from the presence of a rete mirabile.
Greco-Roman medicine
Published in Lois N. Magner, Oliver J. Kim, A History of Medicine, 2017
For Galen's system to work, blood had to pass from the right ventricle to the left ventricle. Some of the blood carried “sooty vapors” to the lungs via the artery-like vein (pulmonary artery). Blood could also pass from the right side to the left side of the heart by means of pores in the septum. The pores themselves were not visible, but Galen assumed that the pits found in the septum were the mouths of the pores. After appropriate digestion in the lungs, inhaled air was brought to the heart by the pulmonary vein. The modified air was further acted on in the heart and transported to other parts of the body by the arteries. Arterial blood was especially fine and vaporous so that it could nourish the vital spirit. Further refinement was accomplished in the arteries that formed the rete mirabile—a network of vessels found at the base of the brain of oxen and other animals (but not in humans). The transformation of arterial blood into animal spirits in the brain and their distribution via the nerves completed the three-fold system of spirits.
Summarizing the medieval anatomy of the head and brain in a single image: Magnus Hundt (1501) and Johann Dryander (1537) as transitional pre-Vesalian anatomists
Published in Journal of the History of the Neurosciences, 2022
Immediately below the brain band but above the eyes is a triangular area of cross-hatching, which is meant to represent K. Rete mirab[i]le (the miraculous net), is a finely reticulated network of blood vessels at the base of the brain that, according to Galen, transformed the vital pneuma (i.e., passing with the blood up through the carotid arteries) into the psychic pneuma (Galen 1968). However, the human rete mirabile is a medieval fiction inherited from anatomists of the classical period (e.g., Herophilus and Galen), who assumed (incorrectly) that certain structures present in some other mammals were also present in humans (Clarke and O’Malley 1996; Galen 1968; Herophilus 1989; Lanska 2015). Belief in the human rete mirabile persisted from classical times through the medieval period and even beyond, but the structure does not exist in humans. One difficulty with identifying the rete mirabile in this figure is typographical: The structure is identified in the left-side legend with a Gothic majuscule K, but there is a much different Gothic K with a stem that arcs above the rest of the letter toward the right and, as printed, misleadingly resembles K or possibly an R with an ornamental extension of the stem projecting upward and tilted toward the right over the so-called “arm” and “leg” of the letter (Coles 2012; Haley et al. 2012).
Evolution of the myth of the human rete mirabile traced through text and illustrations in printed books: The case of Vesalius and his plagiarists
Published in Journal of the History of the Neurosciences, 2022
Now, examining the observed ungulate pattern of the rete mirabile from Vesalius (1543a) and selected copyists, on both sides of the original the vascular meshwork extends from the side of a large vessel; above and below this, vascular branches of the larger vessel are represented by a Y-shaped vessel pattern.