FIGURE 2. Position vectors of major neck muscles in Tyrannosaurus rex (AMNH 5027; skeletal drawings modified from Paul 1988), with the neck in a neutral to slightly elevated posture. Note that 3-D summation of these vectors yields direction for lines of muscle pull. Muscle abbreviations, origins, and insertions are as listed in Table 1; dots indicate attachment sites and via points. The top figure shows the scale, and vector axes in the frontal and sagittal planes. A, C, and E depict the skeleton and lines of action in dorsal view, and B, D, and F show these in lateral view. In B and E, bones of the neck are shown as dashed lines so that muscle lines of action are not obscured. In C and D, bones are shown as dashed lines to indicate that M. r. c. v. passes ventral or medial to them. A, B, M. longissimus capitis superficialis (M. long. cap. sup.: dark lines) and M. complexus (lighter-shaded lines). C, D, M. longissimus capitis profundus (M. long. cap. prof.; dashed black lines in D) and M. rectus capitis ventralis (M. r. c. v.). E, F, M. transversospinalis capitis (M. trans. cap.: dark gray lines) and M. iliocostalis capitis (M. il. cap.: black lines).