A morphological study of the multi infraorbital canals of the maxilla in the Japanese macaque by cone-beam computed tomography.

The infraorbital canal in the Japanese macaque is composed of main and accessory canals. However, the morphological features of the infraorbital canal, such as the canal course and the supply of infraorbital vessels and nerves in the maxilla, are poorly characterized. In this study, we show the structure of the infraorbital canal of the Japanese macaque (adults; 10 male, 9 female), including the distribution of these vessels and nerves, using cone-beam computed tomography and a macroscopic apparatus. The superior and lateral margins of the orbit were correlated with the infraorbital canal on three-dimensional reconstruction images (P<0.05). We classified three types of multi infraorbital foramina as follows: type 1 had one accessory foramen, type 2 had two accessory foramina, and type 3 had three accessory foramina in the infraorbital canal. The infraorbital canal also formed three structures, specifically, a tube-like shape, a funnel shape, and a pinched shape. The accessory canals also contained nerves and blood vessels, and the canals ran downward and supplied the maxillary sinus, teeth, and midfacial region of the craniofacial skeleton, while passing through a few branch canals. These accessory canals proved valuable for blood vessels and nerves and allowed us to recognize the maxilla in the Japanese macaque skull.