Fig. 21. Schematic summary of the movements of the entire buccal mass during a swallowing cycle. This summary, which supersedes fig. 10 of Drushel et al. (1997), is based on the data presented in the present paper and in Neustadter et al. (2002) and incorporates observations from in vivo high-temporal-resolution MRIs taken in intact, behaving animals as well as high-spatial-resolution MRIs of anesthetized buccal masses. Details not visible in the MRIs are based on observations of buccal masses or isolated odontophores undergoing pharmacologically induced feeding-like movements and on dissections of fresh and fixed buccal masses. All illustrations are in orthographic projection. (A) A superficial lateral view of the outer buccal mass. (B) A mid-sagittal view. (C) A dorsal view. In C, the upper half of each diagram depicts a superficial dorsal view, whereas the lower half depicts a view in which the radular surface and the I4 muscles are transparent, showing the ventral structures beneath them. Columns 1-6 correspond to frames 15, 19, 25, 30, 35 and 37, respectively, of sequence 7732-S3. The circumferential muscle shown in C4 was designated as such by Starmühlner (1956). The nomenclature for the other intrinsic muscles follows Howells (1942) and Evans et al. (1996), and the nomenclature for the extrinsic muscles follows Chiel et al. (1986) and Howells (1942).

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