Meeting Abstract
3D printing offers a novel avenue for hands-on science and classroom laboratory exercises because it allows students to actually feel 3D anatomy and physically measure attributes of models. Classical studies using authentic skeletal material are phenomenal, but it can be difficult to exclusively demonstrate a single physical attribute (e.g. jaw-closing out-lever) without confounding anatomical change. We have designed a laboratory exercise where students physically measure (using calipers) mechanical parameters of 3D-printed skulls (e.g. lever mechanics of the jaw) and anatomical determinants of muscle force (muscle belly volume) to calculate biting force in two distinct 3D printed models: a dog and a primate. Then, alternative models of muscle architecture are used whereby muscle fiber length either: 1) spans the entirety of MTU length; or 2) is the shortest possible length to create a contracting moment (i.e. is almost perpendicular to the MTU line of action). The third step in the exercise involves a digitally altered primate skull, whereby the out-lever (i.e. the rostrum and anterior teeth) has been digitally elongated to give the same mechanical advantage (in-lever to out-lever ratio) as the dog, but without altering the input muscle force, mechanical advantage, or adductor muscle volume. This exercise effectively leverages (pun completely intended) the utility of 3D printing to underscore specific anatomical characteristics (e.g. jaw output lever change) without confounding factors (e.g. cranial elongation).
