Meeting Abstract

P3.161  Sunday, Jan. 6  Comparative Anatomy of the Digastric Muscle: a Preliminary Study KOEPPL, H.B.**; OSBORNE, J.P.B.; DRUZINSKY, R.E.; Univ. of Illinois, Chicago; Univ. of Illinois, Chicago; Univ. of Illinois, Chicago druzinsk@uic.edu

Of all the mammalian muscles of mastication, the digastric is one of the most interesting. In most mammals it is formed by merging two muscles, the anterior and posterior digastrics, innervated by the trigeminal and facial nerves, respectively. But the architecture and bony attachments vary widely across the Mammalia. To understand this variation we have begun to survey the anatomy of the digastrics using the published literature and through new examinations via traditional gross dissection of formaldehyde-fixed heads and sections of polymer-embedded specimens. To date, we have studied mice, Mus musculus, prairie voles, Microtus ochrogaster, and opossums Didelphis virginiana. With this survey we are developing a new system for encoding variation in the digastric muscle, which will allow us to generate parsimonious phylogenetic reconstructions of these morphological variations with analytical software such as Mesquite (Maddison and Maddison, 2010).