Fascicle measurement methods do result in lengths that are significantly different
Abstract
Fascicle length is a key anatomical variable used to estimate functional adaptations of muscles. Although a recent study concluded that the fascicles measured on different specimens using in situ measurement and chemical dissection yield results that are not significantly different, these two methods have not been systematically tested within individual specimens. To that end, we compare the two measurement techniques on contralateral sides of (1) carnivoran masticatory muscles and (2) rat leg muscles to evaluate their statistical comparability. Our results show that the two methods result in statistically significant fascicle length differences, with in situ measurements being significantly greater in architecturally simpler muscles across a weighted average of masticatory muscles and among individual muscles. This trend holds for the rat soleus muscles but is reversed for the architecturally more complex gastrocnemius, with chemical dissection resulting in greater fascicle lengths. This suggests that pennation may influence methodological compatibility, with more complex connective tissue potentially obscuring fascicle ends and architecturally simpler muscles being prone to stretching when measured in situ. Given the importance of this anatomical measure, these results have potentially wide implications. Although small muscles with complex connective tissue yield shorter fascicle lengths when measured in situ, in general, in situ measurements are significantly longer by a factor of 1.3. Comparing fascicles measured using these traditional methods and through imaging techniques like DiceCT and micro-MRI, which allow evaluation of intact specimens, may provide further insight into the true anatomical reliability of these methods that unambiguously produce significantly different measurements.
Related
- hicream: A flexible framework to identify significantly different regions in Hi-C data
- Comparative evaluation of tip diameter of different gutta-percha cones according to ISO 6877 measurement method and direct measurement method: an in vitro study
- Comparative assessment of phytoplankton community using different filtration methods based on environmental DNA metabarcoding—a case study of Caohai Wetland
- Effect of different reheating methods on the formation of volatile compounds in pre-cooked meatballs
- Management of Root-Knot Nematode-Fusarium Wilt Complex with different Bio-management methods in Tomato (Solanum lycopersicum L.) var Srijana
BibTeX
@article{clark2026fascicle,
title = {{Fascicle measurement methods do result in lengths that are significantly different}},
author = {Katherine M Clark and Reece A Brown and Maggie Funderburk and Elise S Bush and Anthony Herrel and Adam Hartstone‐rose},
journal = {The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology},
year = {2026},
month = jul,
doi = {10.1002/ar.70301},
url = {https://hal.science/hal-05763677v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Fascicle measurement methods do result in lengths that are significantly different
AU - Katherine M Clark
AU - Reece A Brown
AU - Maggie Funderburk
AU - Elise S Bush
AU - Anthony Herrel
AU - Adam Hartstone‐rose
PY - 2026
DA - 2026/07/30
JO - The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
DO - 10.1002/ar.70301
UR - https://hal.science/hal-05763677v1
AB - Fascicle length is a key anatomical variable used to estimate functional adaptations of muscles. Although a recent study concluded that the fascicles measured on different specimens using in situ measurement and chemical dissection yield results that are not significantly different, these two methods have not been systematically tested within individual specimens. To that end, we compare the two measurement techniques on contralateral sides of (1) carnivoran masticatory muscles and (2) rat leg muscles to evaluate their statistical comparability. Our results show that the two methods result in statistically significant fascicle length differences, with in situ measurements being significantly greater in architecturally simpler muscles across a weighted average of masticatory muscles and among individual muscles. This trend holds for the rat soleus muscles but is reversed for the architecturally more complex gastrocnemius, with chemical dissection resulting in greater fascicle lengths. This suggests that pennation may influence methodological compatibility, with more complex connective tissue potentially obscuring fascicle ends and architecturally simpler muscles being prone to stretching when measured in situ. Given the importance of this anatomical measure, these results have potentially wide implications. Although small muscles with complex connective tissue yield shorter fascicle lengths when measured in situ, in general, in situ measurements are significantly longer by a factor of 1.3. Comparing fascicles measured using these traditional methods and through imaging techniques like DiceCT and micro-MRI, which allow evaluation of intact specimens, may provide further insight into the true anatomical reliability of these methods that unambiguously produce significantly different measurements.
SN - 1932-8486
SN - 1932-8494
ER -