A nonlinear finite-element model of the newborn middle ear.
A three-dimensional static nonlinear finite-element model of a 22-day-old newborn middle ear is presented. The model includes the tympanic membrane (TM), malleus, incus, and two ligaments. The effects of the middle-ear cavity are taken into account indirectly. The geometry is based on a computed-tomography scan and on the published literature, supplemented by histology. A nonlinear hyperelastic constitutive law is applied to model large deformations. The middle-ear cavity and the Young's modulus of the TM have significant effects on TM volume displacements. The TM volume displacement and its nonlinearity and asymmetry increase as the middle-ear cavity volume increases. The effects of the Young's moduli of the ligaments and ossicles are found to be small. The simulated TM volume changes do not reach a plateau when the pressure is varied to either -3 kPa or +3 kPa, which is consistent with the nonflat tails often found in tympanograms in newborns. The simulated TM volume displacements, by themselves and also together with previous ear-canal model results, are compared with equivalent-volume differences derived from tympanometric measurements in newborns. The results suggest that the canal-wall volume displacement makes a major contribution to the total canal volume change, and may be larger than the TM volume displacement.
Qi
Li
L
Department of BioMedical Engineering, McGill University, Montréal H3A2B4, Canada.
Funnell
W Robert J
WR
Daniel
Sam J
SJ
D004432:Ear, Middle / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D006309:Hearing / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D008953:Models, Anatomic; D014057:Tomography, X-Ray Computed