We measured the calibers of the left and right internal jugular veins (IJV) and sizes of the left and right transverse sinuses (TS) in 91 cadavers, compared them between the left and right sides, and also evaluated the drainage patterns of the superior sagittal sinus (SSS) and straight sinus (=rectal sinus, RS) in the torcular Herophili. In addition, the running type of groove for the SSS was investigated. The results were as follows: (1) The right IJV was larger in 81.3 %, while the left IJV was larger in only 11.0 %. (2) The drainage pattern of the SSS was the right type in 73.6 %, intermediate type in 14.3 %, and left type in 12.1 %. (3) The drainage pattern of the RS was the right type in 27.5 %, intermediate type in 25.3 %, and left type in 47.3 %. (4) The running type of groove for the SSS was mostly consistent with the drainage pattern of this sinus. (5) Concerning the relationships among these findings including the size of the TS, the drainage pattern of the SSS was mostly consistent with the side showing a larger TS as well as the side showing a larger IJV. These results suggest that the pattern of drainage of the SSS into the left and right TS affects the size of the TS and the running type of groove for the SSS, and is also closely involved in the caliber of the IJV. A discussion of the embryological, genetic, and clinical implications of these results is presented.

The rarity of achalasia has led to limited opportunities for practical training in educational environments. Cadaver surgical training was developed to enhance surgical skills by providing physicians with experience comparable to that of on-the-job training using structures identical to living organs, thereby proving highly beneficial. Recently, cadavers have been preserved using the Thiel method, which maintains both mobility and organizational flexibility. However, there are few reports on therapeutic endoscopy, including peroral endoscopic myotomy, in the context of cadaver surgical training. We investigated the feasibility of using cadaver surgical training for therapeutic endoscopy training, termed Cadaver-based Therapeutic Endoscopy Training, for peroral endoscopic myotomy. This study was conducted in 2024 at the Cadaver Surgical Center of Nagasaki University using four cadavers preserved using the Thiel method. We performed peroral endoscopic myotomies on three cadavers and evaluated the observability of the esophageal mucosa, penetration of the local injection fluid, feasibility of creating a submucosal tunnel, visibility of indocyanine green injection, and inner circular muscle incision. The layered structure of the digestive tract was well preserved in the Thiel-fixed cadavers, and peroral endoscopic myotomy was performed without major issues. Cadaver-based Therapeutic Endoscopy Training may serve as a realistic training model comparable to living organs and may be beneficial for peroral endoscopic myotomy training.

Lumbar lordosis influences load transmission in the lumbar spine, but its effects on stress in the anterior cortical bone of the vertebral bodies remain unclear. This study investigated how lumbar lordosis angle (LL) affects vertebral stress. A finite element model from T12 to the sacrum was constructed from computed tomography images of a cadaver from a 66-year-old male donor. Three models with identical bone geometry and material properties but LL values of 50°, 30°, and 15° were analyzed under a 300 N compressive load and the same load combined with a 5 N·m flexion moment. Mean von Mises stress and the 95th percentile of von Mises stress were evaluated in the anterior cortical bone of L1–L5, and vertebral-level distributions were normalized to L1. Under both loading conditions, the LL15° model showed higher von Mises stress than the LL50° and LL30° models at all vertebral levels. Adding the flexion moment further increased stress in all models. Normalized stress was lowest at L3 in the LL50° and LL30° models, whereas values in the LL15° model remained relatively close to L1 across L2–L5. These findings suggest that models with lower LL exhibit higher anterior cortical bone stress and altered vertebral-level stress distributions.