Author:
Wei Qi,Mutawak Bassam,Demer Joseph L.
Abstract
AbstractThe Active Pulley Hypothesis (APH) is based on modern functional anatomical descriptions of the oculomotor plant, and postulates behaviors of the orbital pulleys proposed to be positioned by the extraocular muscles (EOMs). A computational model is needed to understand this schema quantitatively. We developed and evaluated a novel biomechanical model of active horizontal rectus pulleys. The orbital (OL) and global (GL) layers of the horizontal rectus EOMs were implemented as separate musculoskeletal strands. Pulley sleeves were modeled as tube-like structures receiving the OL insertion and suspended by elastic strands. Stiffnesses and orientations of pulley suspensions were determined empirically to limit horizontal rectus EOM side-slip while allowing anteroposterior pulley travel. Independent neural drives of the OL greater than GL were assumed. The model was iteratively refined in secondary gazes to implement realistic behavior using the simplest mechanical configuration and neural control strategy. Simulated horizontal rectus EOM paths and pulley positions during secondary gazes were consistent with published MRI measurements. Estimated EOM tensions were consistent with the range of experimentally measured tensions. This model is consistent with postulated bilaminar activity of the EOMs, and the separate roles of the GL in ocular rotation, and OL in pulley positioning.
Funder
National Eye Institute
Research to Prevent Blindness
Publisher
Springer Science and Business Media LLC
Reference32 articles.
1. Demer, J. L. Pivotal role of orbital connective tissues in binocular alignment and strabismus: The Friedenwald lecture. Investig. Ophthalmol. Vis. Sci. 45, 729–738 (2004).
2. Miller, J. M. Functional anatomy of normal human rectus muscles. Vis. Res. 29, 223–240. https://doi.org/10.1016/0042-6989(89)90126-0 (1989).
3. Miller, J. M., Demer, J. L. & Rosenbaum, A. L. Effect of transposition surgery on rectus muscle paths by magnetic resonance imaging. Ophthalmology 100, 475–487 (1993).
4. Clark, R. A., Miller, J. M. & Demer, J. L. Three-dimensional location of human rectus pulleys by path inflections in secondary gaze positions. Investig. Ophthalmol. Vis. Sci. 41, 3787–3797 (2000).
5. Clark, R. A., Miller, J. M. & Demer, J. L. Location and stability of rectus muscle pulleys. Muscle paths as a function of gaze. Investig. Ophthalmol. Vis. Sci. 38, 227–240 (1997).
Cited by
3 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献