Transformation of Muscle Architecture at the Fiber Bundle Level to Fit Parametric B-spline Volumes: Extensor carpi radialis brevis and longus

Most models of the musculoskeletal system incorporate individual or groups of muscles as a series of line segments, assuming all fiber bundles within a muscle have the same length and moment arm, and do not account for architectural differences throughout the muscle volume. The purpose was to develop an algorithm to fit digitized fiber bundle data from one specimen into muscle volume and intramuscular nerve distribution data from seven other specimens of extensor carpi radialis longus (ECRL) and brevis (ECRB). Coherent Point Drift (CPD) algorithm was successfully adapted for this purpose. The intramuscular nerve distribution and fiber bundle architecture was modeled in all the muscle volumes. ECRL was found to have two neuromuscular compartments, superficial and deep, while ECRB was found to have two, three or four, in a proximal to distal direction depending on the number of primary nerve branches.MAS