A New Method of Locating Foramen Rotundum and its Anatomic Study Ye Cheng, PhD, MD,* Hongquan Yu, MD,* Songbai Xu, MD,* Haiyang Xu, MD,* Siwen Zhang, PhD, MD,† Qingchun Mu, MD,* Yunqian Li, MD,* and Gang Zhao, MD* Purpose: The purpose of this study is to provide a new method to locate the foramen rotundum (FR) based on the structures in the wall of sphenoid. Materials and Methods: Computed tomographic angiography images of 172 FR in adults and 10 bony specimens were reviewed. The measurement was on coronal, sagittal, and axial planes after multiplanar reconstruction. The diameter, length, and direction of FR were measured. The middle lowest point of sellar region, the sagittal midline, and the bottom of sphenoid sinus were selected as the landmarks to locate the FR. Result: The FR can be found and identified easily on computed tomographic angiography image. The bony diameter measured in CT image is in accordance with that in specimen. The anterior open- ing and posterior opening can be located by the stationary structures in the sphenoid sinus. Conclusions: The FR is a stationary bony structure; its length, di- ameter, and angle are relatively constant; and it can be easily located by the data measured in this study. The FR should be protected in the process of transsphenoid approach as well as be precisely located by the procedure about it. Key Words: FR, sphenoid sinus, surgical anatomy, transsphenoidal surgery (J Craniofac Surg 2015;26: 528–531) F oramen rotundum (FR) is the inherent bony structure in the bases of skull and located in the alae magna ossis sphenoridalis of fossae cranii media. The FR is adjacent to foramina ovale and foramina spinosum. The second branch of the trigeminal nerve is through the FR. The FR is located adjacent to the nasopharynx and often violated by the nasopharyngeal cancer and other malig- nant brain tumor. 1 Besides, FR is also close to pterygopalatine fossa (PPF), pterygoid canal, and palatovaginal canal, which made it closely related to the transsphenoid sinus surgery and the extended transsphenoid sinus surgery. Thus, FR is regarded as an important landmark. 2 Recently, the development of the endoscopic has made it possible for the structures around the sphenoid sinus such as the internal carotid artery, optic canal, PPF, and antrum maxillary to get access to the region of the FR. Moreover, the maxillary nerve block through FR 3 is related to the position. Therefore, a compre- hensive anatomic study of FR is of great clinical meaning. Previous literature has made an anatomic future in some aspect of FR, 4 but a three-dimensional location of it based on the landmarks in the sphenoid cavity is also necessary. The purpose of this study is to provide a new method to locate the FR based on the structures in the wall of sphenoid. MATERIALS AND METHODS Computed tomographic angiography images of 172 FR in adults (98 men and 74 women) ranging in age from 15 to 78 years (mean, 48.8 y) were reviewed. All the computed tomographic an- giography images were obtained by the Siemens 64-row spiral CT (0.625 mm between 2 pictures) in the First Hospital of Jilin University. Images displaying sphenoid sinus disease, sphenoid bone fracture, and PPF or FR deformity (12 of the 184) were excluded from the study. The measurement was on coronal, sagit- tal, and axial planes after multiplanar reconstruction. The relationship between FR and sphenoid sinus can be classified into 3 types according to the formation of protuberance into the sphenoid sinus: type 1, significant protuberance into the sphenoid cavity; type 2, adjacent to the sphenoid but without the protuberance; and type 3, FR is away from the sphenoid sinus (Figs. 1A, B). The anterior and posterior openings of FR were iden- tified in the axial plane (Fig. 2A), the coronal plane through the anterior opening of FR was defined as plane 1, and the coronal plane through the posterior opening of FR was defined as plane 2 (Fig. 2A). The distance between the anterior (posterior) opening of FR and the middle lowest point of sellar region (SF) were From the Departments of *Neurosurgery and †Endocrine, First Hospital of Jilin University, Changchun, Jilin, China. Received June 28, 2014. Accepted for publication September 14, 2014. Address correspondence and reprint requests to Yunqian Li, MD, No 71 Xinmin Street, Chaoyang District, 130021 Changchun, Jilin Province, China; E-mail: liyunqian_jdyy@sina.com Ye Cheng and Hongquan Yu contributed equally to this work as first authors. The authors report no conflicts of interest. Copyright © 2015 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001351 FIGURE 1. A, The classification of FR. FRI, The FR of type 1: FR forms significant protuberance into the sphenoid cavity. FRII, FR of type 2: FR is adjacent to the sphenoid but without the protuberance. B, FRIII, FR of type 3: FR is away from the sphenoid sinus. SS, sphenoid sinus. ANATOMICAL STUDY 528 The Journal of Craniofacial Surgery • Volume 26, Number 2, March 2015 Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.