Relation Between the Conduction Velocity of Nerve Fibers, Micro‐anatomical Parameters and the Divine Proportion (Φ=1.618) ‐ A new Paradigm

Abstract

The Divine Proportion (DP) (Φ=1.618) is found in several natural phenomena and in different human anatomical proportions, such as cephalometric measurements, anatomical organization of the hands and functional and esthetic organization of dentition. Recent studies have described that structures or systems organized based on DP are more stable, aesthetically more pleasurable and functionally more eficiente as they follow mathematically the biological laws. The aim of this study was analyze the DP and other micro‐anatomical parameters in a pair of nerves with similar function, but with different velocities of conduction of nerve impulse ‐ the recurrent laryngeal nerves (RLN) left and right ‐ in which the right RLN presents a larger velocity of nerve impulse conduction. Seven RLN of cadavers obtained from necropsies were analyzed with mathematical, stereological and images tools using the Software Image Pro‐Plus Software 6.0. The micro‐anatomical comparison between the right and left RLN showed that the following parameters of the right RLN are significantly larger: axon diameter (11.2%, p=0.001) and myelinated fiber diameter (20.6%, p=0.0001). The left RLN had a G‐ratio significantly larger than the right RLN (10.3%, p=0.0093). There is a significant difference in DP between the right and left RLN (p=0.0047), in which the right RLN has a perfect value of DP (Φ=1.6), while the left RLN has a value of Φ=1.4. Possibly, the conduction velocity of nerve impulse may not be only affected by the presence of myelin sheath and by axon diameter, but also by “perfect” morphology of nerve fiber.