The biomechanics of the human tongue

The human tongue is composed mainly of skeletal-muscle tissue, and has a complex architecture. Its anatomy is characterised by interweaving, yet distinct muscle groups. It is a significant contributor to the phenomenon of Obstructive Sleep Apnea (OSA). OSA is a pathological condition defined as the partial or complete closing of any part of the human upper airway (HUA) during sleep. OSA syndrome affects a significant portion of the population. Patients with OSA syndrome experience various respiratory problems, an increase in the risk of heart disease, a significant decrease in productivity, and an increase in motor-vehicle accidents [58]. The aim of this work is to report on a constitutive model for the human tongue, and to demonstrate its use in computational simulations for OSA. A realistic model of the constitution of the tongue and computational simulations are also important in areas such as linguistics and speech therapy [44]. The detailed anatomical features of the tongue have been captured using data from the Visible Human Project (VHP) [102]. The geometry of the tongue, and each muscle group of the tongue, are visually identified, and its geometry captured using Mimics [100]. Various image processing tools available in Mimics, such as image segmentation, region-growing and volume generation were used to form the three-dimensional model of the tongue geometry. Muscle fibre orientations were extracted from the same dataset, also using Mimics.The muscle model presented here is based on Hill’s three-element model for representation of the constituent parts of muscle fibres. This Hill-type muscle model also draws from recent work in muscle modelling, by Martins [88]. The model is implemented in an Abaqus user element (UEL) subroutine [24]. The transversely isotropic behaviour of the muscle tissue is accounted for, as well as the influence of muscle activation. The mechanics of the model is limited to static, small-strain, anisotropic, linear-elastic behaviour, and the governing equations are suitably linearized. The body position of the patient during an apneic episode is accounted for in the simulations, as well as the effect of gravity. The focus of this study is on tongue muscle behaviour under gravitational loading, simulating a simplified OSA event. Future models will incorporate airway pressure as well. The behaviour of the model is illustrated in a number of benchmark tests, and computational examples.

Grantor dc:publisher.institution

Department of Mechanical Engineering

Year dc:date.issued

2010

Author dc:creator

• Kajee, Yaseen

Advisor dc:contributor.advisor

• Reddy, B D

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/5525

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/5525