Physically correlated muscle activation for a human head and neck computational model

Abstract

A computational 50th percentile male head and neck complex model was correlated to physical experimental data. The computational model utilizes 15 muscle pairs represented by the Hill Muscle Model with the complete head/neck system modeled using MADYMO. The model was used for analysis and optimization of activation and deactivation of muscle activity in flexion and extension. Sensitivity analysis performed using the model shows that, of the multiple parameters within the Hill Model, activation level and timing prove to have the greatest effect on the system kinematics. In addition, the rate by which an activation level is changed becomes an important factor in the simulation. With the use of numerical optimization techniques, a pattern was determined for the applied activation/deactivation rates and timing of flexors and extensors during flexion and extension of the head. The numerical optimization result correlated to within 9% of measured value during the initial flexion of the head. The optimized activation model reflected an activation onset 90 ms after the start of the impulse load, which agrees with published reaction times of muscles. Activation and deactivation rates for the extensors were found to be 1.7 and 0.29%, respectively. While the onset of activation of the flexor muscles occurred before rebound, it was found that muscles, at near the mid-plane, were triggered by the optimized model to abate the flexion. Rates of activation and deactivation of the flexors were found to be 0.9 and 0.3%, respectively. Both the extensors as well as the flexors were found to activate only up to 70% before deactivating. Therefore, it was evident from this study that using the Hill Muscle Model with the activation parameter modeled as binary, 0 or 100%, may lead to inaccurate simulation results.

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

“…Still others failed to report whether gravity was included in their simulations (Deng and Goldsmith 1987;Golinski and Gentle 2005;Lee et al 2004;Meyer et al 2004;Stemper et al 2004). A select few studies reported determining gravitational stabilization muscle activation schemes that were initiated before simulation loading (Brelin-Fornari et al 2005;Chancey et al 2003;Deng and Fu 2002;Östh et al 2012). Chancey et al (2003) reported a method to find relaxed and tensed optimal cervical muscle activations, representing neck properties of both unaware and aware subjects.…”

Linear Homeomorphic Models for Muscles in the Head–Neck Region

“…Anatomical data about the attachment sites and force-generating parameters for the muscles are presented by Vasavada et al 29 Also, detailed descriptions of the morphology of the neck muscles are found in Brelin-Fornari et al, 2 Kamibayashi and Richmond, 17 and Richmond et al 23 To create a physiologically correct model, images from the Visible Human project are used to locate the insertion and origin points of the muscles. 4 To consider multiple attachment points, some muscles are described as consisting of different submuscles, with the total physiological cross section area being equal to that presented in the literature.…”