The Role of the Deep Cervical Extensor Muscles in Multi-Directional Isometric Neck Strength - Associated Model and Code

Published: 16 April 2024| Version 2 | DOI: 10.17632/jm5dhwwmyd.2


The purpose of this study was to determine the effects of deep cervical extensor muscle (multifidus and semispinalis cervicis) weakness on multi-directional neck strength and muscle activation patterns. Maximum isometric forces and associated muscle activation patterns were computed in 25 test directions using a 3-joint, 24-muscle musculoskeletal model of the head and neck. Our computational approach accounted for the differential torques about the upper and lower cervical spine. The manuscript associated with this data has been accepted for publication in the Journal of Biomechanics.


Steps to reproduce

See the readme file for detailed descriptions of the code. The MATLAB code includes classes with functions to interact with an OpenSim model through the MATLAB API. Note that OpenSim must be installed on your device and the MATLAB environment must be set up appropriately. The computeFWS function uses a linear programming approach to compute the maximum isometric strength and muscle activation pattern in each provided direction, given the model parameters. For convenience, several .mat files are included in the Data folder that contain all of the necessary model parameters required to reproduce the data, without the need for interacting with OpenSim or the OpenSim MATLAB API. The provided code includes an OpenSim neck model that can be used in OpenSim 4.0 or greater. The model is intended for simulating isometric strength, so it may not be appropriate for dynamic simulations. The OpenSim neck model was derived from the Vasavada Neck Model 1.6 [1] and the Mortensen neck model with the hyoid muscles included [2]. The neck model was then updated to be compatible with OpenSim 4.0 to allow for MATLAB API functionality. [1] Vasavada, AN, Li, S, Delp SL. Influence of muscle morphometry and moment arms on the moment-generating capacity of human neck muscles. Spine, 23(4):412-422. (1998) Model available at: [2] Mortensen, J. D., Vasavada, A. N., & Merryweather, A. S. (2018). The inclusion of hyoid muscles improve moment generating capacity and dynamic simulations in musculoskeletal models of the head and neck. PloS one, 13(6), e0199912. Model available at:


University of Colorado, Northwestern University, University of Minnesota


Biomechanics, Computational Modeling, Neck, Spine, Musculoskeletal Rehabilitation


National Institutes of Health


National Institutes of Health


National Institutes of Health