Anatomical Localization and Acupuncture Pathway of the Sphenopalatine Ganglion in Sprague-Dawley Rats: A Microanatomical Study

ZHAO YUECHUN¹Lei Li¹Mingjiang Yao¹XIAOJING AN¹JING WANG¹ZHENGYANG LI¹HANXI DAI¹JINXIN DAI¹LI LIU²LU ZHANG^1*

• ¹China Academy of Chinese Medical Sciences Xiyuan Hospital, Beijing, China
• ²Capital Medical University, Beijing, China

Abstract: Background: The sphenopalatine ganglion (SPG) plays a pivotal role in regulating various head and facial diseases, such as cluster headaches, allergic rhinitis, and cerebral ischemia, through its neuroregulatory functions. Current interventions targeting SPG, have certain limitations, such as invasiveness and high cost. Acupuncture, which shows unique advantages, lacks standardized animal models for experimental research. Objective: To investigate the spatial anatomical localization of the SPG in Sprague-Dawley (SD) rats and to establish an effective acupuncture pathway for SPG. Methods: A total of 12 SPF-grade SD rats (6 males and 6 females) were randomly divided into dissection and acupuncture groups. The SPG was microanatomically localized relative to bony landmarks (e.g., sphenopalatine foramen, foramen rotundum). An acupuncture pathway was designed based on anatomical data and validated using digital X-ray fluoroscopy. Serial staining (HE staining, Nissl staining, immunofluorescence staining) was employed to analyze the neural architecture and status within the pterygopalatine fossa region. Results: The SPG was located laterally to the sphenopalatine foramen, with coordinates for males being X = +0.05 ± 0.03 mm, Y = -0.62 ± 0.08 mm, and for females X = +0.04 ± 0.01 mm, Y = -0.54 ± 0.06 mm. The acupuncture needle was inserted at the outer canthus, 0.8 – 1.0 cm from the eye’s lateral canthus, at a sagittal angle of 30 – 45° and a coronal angle of 45°, reaching a depth of approximately 1 cm. X-ray fluoroscopy confirmed that the needle tip successfully reached the SPG area. Serial staining results indicated a normal distribution of the neural network in this area and showed no significant structural damage caused by the acupuncture intervention. Conclusion: This study successfully established a precise anatomical coordinate system and a reproducible acupuncture pathway for the SPG in SD rats. These findings provide a technical foundation for experimental acupuncture interventions targeting SPG, which may be beneficial for treating head and facial diseases, such as cluster headaches and allergic rhinitis.