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Does the phenotypic morphology of the human brachial plexus reflect the theoretical development of concomitant regulation in thoracolumbar spines and nerves?


- Department of Anatomy, School of Medicine, Toho University, Tokyo, Japan
open access
Abstract
Background: Experimental evidences identified that thoracolumbar mutants caused by Hox genes 7-10 mutants also involve a craniocaudal shift and/or the addition or reduction of segments of the limb plexus roots. This study investigated whether the theoretical concomitant shift of the brachial plexus roots in human different thoracolumbar counts is shared as confirmed in those of the human lumbosacral plexus.
Material and methods: The phenotypic morphology of the brachial plexus and its arterial interaction on 20 sides of 10 atypical human thoracolumbar counts out of the 354 sides of the 177 cadavers, were compared with those of 52 sides of 26 cases in a typical human vertebral formula (7C_12T_5L_5S).
Results: Regardless of the course and branching patterns of the axillary artery, our results showed that the main brachial plexus roots were composed of only five segments of the 5th–9th spinal nerves, with small contributions from the 4th and/or 10th nerves. This root composition is identical to a typical human thoracolumbar formula, and therefore, neither a craniocaudal shift nor additional/reduced main roots occurred in our thoracolumbar variants.
Conclusions: Unlike the concomitant shift of the lumbosacral plexus roots, our present cases suggest that the phenotypic morphology of the human brachial plexus may be less likely to show theoretical craniocaudal shifts, further data on the root changes in different vertebral formulae are needed for its accurate validation.
Abstract
Background: Experimental evidences identified that thoracolumbar mutants caused by Hox genes 7-10 mutants also involve a craniocaudal shift and/or the addition or reduction of segments of the limb plexus roots. This study investigated whether the theoretical concomitant shift of the brachial plexus roots in human different thoracolumbar counts is shared as confirmed in those of the human lumbosacral plexus.
Material and methods: The phenotypic morphology of the brachial plexus and its arterial interaction on 20 sides of 10 atypical human thoracolumbar counts out of the 354 sides of the 177 cadavers, were compared with those of 52 sides of 26 cases in a typical human vertebral formula (7C_12T_5L_5S).
Results: Regardless of the course and branching patterns of the axillary artery, our results showed that the main brachial plexus roots were composed of only five segments of the 5th–9th spinal nerves, with small contributions from the 4th and/or 10th nerves. This root composition is identical to a typical human thoracolumbar formula, and therefore, neither a craniocaudal shift nor additional/reduced main roots occurred in our thoracolumbar variants.
Conclusions: Unlike the concomitant shift of the lumbosacral plexus roots, our present cases suggest that the phenotypic morphology of the human brachial plexus may be less likely to show theoretical craniocaudal shifts, further data on the root changes in different vertebral formulae are needed for its accurate validation.
Keywords
thoracolumbar mutant, brachial plexus, human development, anatomy, phenotypic morphology, vertebral formula


Title
Does the phenotypic morphology of the human brachial plexus reflect the theoretical development of concomitant regulation in thoracolumbar spines and nerves?
Journal
Issue
Article type
Original article
Published online
2021-09-15
Page views
374
Article views/downloads
190
DOI
10.5603/FM.a2021.0094
Pubmed
Keywords
thoracolumbar mutant
brachial plexus
human development
anatomy
phenotypic morphology
vertebral formula
Authors
T. Kawashima
K. Ishiguro
F. Sato