Geometric structure of the human and canine cricothyroid and thyroarytenoid muscles for biomechanical applications.

The geometric structure of the cricothyroid (CT) muscle and thyroarytenoid (TA) muscle was quantified in 6 human and 3 canine larynges. Each muscle was divided into a series of fiber bundles. With a 3-dimensional micrometer probe, the coordinates of the origin and insertion of each bundle were measured before dissection. It was found that the mass of the CT muscle in the dog was 1.463+/-0.280 g, which was significantly greater than the 0.9423+/-0.123 g found in the human. This was a result of the cross-sectional area of the canine CT muscle being 105.3+/-11.6 mm2 instead of the 73.8+/-7.4 mm2 found for the human. However, the ratios of CT/TA mass and cross-sectional area between the two groups were not significantly different, suggesting that the two muscles grow proportionally.