Comprehensive understanding of the variations in the branches of the infraorbital nerve (ION) is vital to the prevention of iatrogenic nerve injury and successful ION blockade during orbitozygomatic facial procedures. Only a few studies exist on the variant anatomy of the branching patterns of this nerve. This article provides a detailed description of the variations of the nasal and superior labial branches of the ION. This study was performed on 84 IONs by dissecting 42 formalin-fixed cadavers from the Laboratory of Topographic Anatomy, Department of Human Anatomy, University of Nairobi. The branches were exposed at their origin and followed to their termination. The findings included variant emergence patterns, anomalous course, and absence as well as extra branches. It was noted that the external nasal nerve was absent in 34.53% cases. There were common trunks between the internal and external nasal nerves and cases of communication between branches of these nerves were also noted. Accessory superior labial nerves were present in 9.52% of the nerves. This detailed study reveals additional variations in the emergence and branching pattern of the ION. Caution is imperative during orbitozygomatic facial surgery to prevent injury to these branches. These variations also underlie the lack of response to surgical treatment for trigeminal neuralgia and also the need for a filtration to achieve full anesthesia after ION block. In addition, the extra branches identified raise the prospects of using these nerves for grafting purposes if their precise patterns are determined.
Keywords: external nasal nerve; superior labial nerve; variation.