Open AccessFunctional Anatomy of Incisal Biting in <i>Aplodontia rufa</i> and Sciuromorph Rodents – Part 2: Sciuromorphy Is Efficacious for Production of Force at the Incisors
Author(s) -
Robert E. Druzinsky
Publication year - 2010
Publication title -
cells tissues organs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.662
H-Index - 82
ISSN - 1422-6405
DOI - 10.1159/000284930
Subject(s) - masticatory force , anatomy , biting , mastication , biology , bite force quotient , orthodontics , medicine , ecology , paleontology
The protrogomorph condition of the rodent masticatory apparatus is thought to be present in only one living species, the mountain beaver Aplodontia rufa. The major anatomical difference between protrogomorphs and sciuromorphs is that the relative size of one part of the masseter muscle, the anterior lateral masseter, is much greater in sciuromorphs than in protrogomorphs. The mechanics of force production at the incisors were compared in A. rufa and six sciuromorph rodents. Is the sciuroid masticatory apparatus more effective for production of forces at the incisors during biting than the primitive, protrogomorph condition? To answer this question, three measures of mechanical ability were employed and three hypotheses were tested: (1) the mechanical advantage of the adductor musculature is greater in sciuromorphs than in A. rufa; (2) the relative force produced at the incisors is greater in sciuromorphs than in A. rufa, and (3) the relative amount of force produced that can be used to drive the incisors into an object, is greater in sciuromorphs than in A. rufa. The results demonstrated that the protrogomorph, A. rufa, is not as efficient at generating bite forces at the incisors as the sciuromorphs.