Abstract # 174:

Scheduled for Friday, August 18, 2006 07:00 PM-09:00 PM: Session 17 (Regency West 1/3 ) Poster Presentation

The Anatomy of the Infraorbital Foramen: Implications for Interpreting the Ecology of Extinct and Extant Primates.

M. N. Muchlinski
University of Texas at Austin, Department of Anthropology, EPS 1.130; C3200, Austin, Texas 78712, USA
     Osteological cranial features, such as foramina, are frequently used to interpret the ecology of extinct primates. My current research on the infraorbital foramen (IOF) shows a significant relationship between IOF size and dietary preference. The IOF transmits the afferent sensory infraorbital-nerve (ION) to specialized maxillary mechanoreceptors. If IOF and ION size correlate, IOF size might be indicative of maxillary mechanoreceptivity, an important sensory cue used within a feeding context. However, there is currently debate regarding the validity of using foramen area as a measure of nerve area. Associated vessels may also exit the foramen, and in some instances they constitute the largest proportion of the foramen (e.g., hypoglossal). In other instances, foramina are better indicators of nerve size (e.g., optic). To date, it is unknown what vascular and neural structures pass through the IOF and to what degree each observed structure constitutes the contents of the IOF. Twenty primate and non-primate cadavers were injected with blue and red latex dye to track vascular structures and then the infraorbital area was dissected. Dissections revealed that only the ION and infraorbital-artery pass through the IOF. Furthermore, the infraorbital-artery is exceptionally small, representing a negligible portion of the IOF. These results provide strong evidence that the IOF is an excellent proxy for ION size, and that IOF size may be a useful predictor of relative maxillary mechanoreception.