Fig. 1. Anatomy of the buccal mass, and revision of jaw line measurement. (A) Mid-sagittal anatomy of the buccal mass, based on a formaldehyde-fixed hemi-sectioned buccal mass. (B) External oblique view of dissected buccal mass, showing location of jaw line (lines labeled `Line of jaws'). The I1/I3/jaw complex extends antero-posteriorly from the lateral groove to the jaw line. (C) Line marked `previous' indicates the jaw line used in previous work (Neustadter et al., 2002a). Line marked `revised' is drawn from the dorsal point of inflection of the jaw cartilage, which appears as a dark region, to the ventral point of inflection of the jaw cartilage. This more accurately reflects both the external and internal anatomy of the jaw cartilage, which appears in the MR image as a dark region. (D) Antero-posterior views of three-dimensional kinematic model during swallowing using the new jaw line. Blue mesh represents the I1/I3/jaw complex, yellow mesh represents the odontophore, and red solid represents the radular stalk. (1) Transition, (2) protraction, (3) retraction. These views are based on frames 17, 24, and 35, respectively, of sequence 7732-S3. Compare with the bottom row of fig. 11 in Neustadter et al. (Neustadter et al., 2002b). The revised jaw line generates images that are more similar to those observed during swallowing in vivo.