title: Three-dimensional CT examination of the mastication system in the giant anteater.
abstract: The gross anatomy of the mastication system of the giant anteater (Myrmecophaga tridactyla) was examined by means of three-dimensional image analysis. The anteater rotates the mandibles medially and laterally to control its tongue when it is elongated and to house it when it is relaxed. Three-dimensional CT image analysis demonstrated that the shape and size of the oral cavity changes drastically when the mandibles are rotated. The oral cavity expands bilaterally when the dorsal part of the mandibles bend medially. Macroscopic observations and muscle-weight data supported the observation that the superficial temporal and medial pterygoid muscles act as the main medial and lateral rotators of the mandible, respectively. The low height of the mandibular ramus and the incomplete zygomatic arch in this species represent adaptations for the rotational movement of the mandibles, since they both contribute to the medially oriented transmission of force from the temporal muscles and to preventing collision between the mandibles and the cranium during the rotational movement.
authors: Section of Morphology, Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan. endo@pri.kyoto-u.ac.jp
authors: Hideki
authors: H
authors: Endo
authors: Nobuharu
authors: N
authors: Niizawa
authors: Teruyuki
authors: T
authors: Komiya
authors: Shinichiro
authors: S
authors: Kawada
authors: Junpei
authors: J
authors: Kimura
authors: Takuya
authors: T
authors: Itou
authors: Hiroshi
authors: H
authors: Koie
authors: Takeo
authors: T
authors: Sakai
mesh_terms: D000818:Animals; D000836:Animals, Zoo; D005260:Female; D021621:Imaging, Three-Dimensional / Q000662:veterinary; D008297:Male; D008410:Masticatory Muscles / Q000033:anatomy & histology / Q000502:physiology; D013284:Stomatognathic System / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000662:veterinary*; D004490:Xenarthra / Q000033:anatomy & histology* / Q000502:physiology