The Course of the Trochlear Nerve Presented via a 3-Dimensional Photorealistic Anatomic Model

- OBJECTIVES: Several factors contribute to the anatom- ical complexity of the trochlear nerve, including small diameter, complex and longest intracranial course, deep location, and numerous neurovascular relationships. A 3- dimensional (3D) photorealistic model of the cranial nerves provides a detailed and immersive representation of the anatomy, enabling one to improve surgical planning, advanced surgical research, and training. The purpose of this work is to present a 3D photogrammetric study for a more intuitive and interactive way to explore and describe the entire course of trochlear nerve. - METHODS: Two injected-fixed head human specimens (4 sides) were examined. The dissection protocol was divided into the following steps: 1) brain hemisphere exposure; 2) hemispherectomy dissecting all cranial nerves and partial removal of the free edge of the tento- rium; 3) middle fossa and lateral wall of cavernous sinus exposure; and 4) orbital exposure. A detailed 3D photo- grammetric model was generated for each dissection step. - RESULTS: Four main volumetric models were generated during a step-by-step layered dissection of the entire nerve pathway highlighting its different segments. Finally, a full and integrated model of the entire course of the nerve was created. The models are available for visualization on monoscopic display, virtual, and augmented reality environment. - CONCLUSIONS: The present photogrammetric model provides a more comprehensive understanding of the nerve’s anatomy in its different segments, allows for cus- tomizable views thus simulating different perspectives, and can be a valuable alternative to traditional dissections. It is an advanced tool for surgical planning and surgical simulation as well as virtual reality representation of the anatomy.