Ultrasonographic Assessment of Anatomical Structures Surrounding PC7 in Relation to the Median Nerve

ㆍ이향숙 1,9,10 1 경희대학교 대학원 경락의과학과, 2 바로한의원, 3 부산대학교 한의학전문대학원 침구의학과, 4 금강한의원, 5 마포홍익한의원, 6 오롯한의원, 7 원광대학교 한의과대학 경혈학교실, 8 원광대학교 한의과대학 진단학교실, 9 경희대학교 한의과대학 침구경락융합연구센터, 10 경희대학교 한의과대학 해부학교실 Objectives : While PC7 is frequently used for both distal and proximal needling, its detailed anatomical understanding remains limited.This study aimed to characterize anatomical structures surrounding PC7 using ultrasonography, quantify the frequency and spatial relationships between PC7 and the median nerve (MN) and its palmar branch (PB), and clarify clinical implications for proximal needling.Methods : In this retrospective observational study, 50 adults (100 wrists) with wrist pain but no ultrasonographic abnormalities were recruited from two Korean Medicine clinics between December 2022 and January 2023.Ultrasound scanning was performed at the World Health Organization (WHO)-defined PC7 level.The vertical depth of PC7 was determined from pre-Qing classical acupuncture texts.Anatomical structures were identified, and quantitative measurements were obtained for the MN and PB, including their presence, depth, and distance from the palmaris longus (PL) and flexor carpi radialis (FCR) tendons.Statistical analyses evaluated factors related to MN presence and its occupation within PC7. Results : Identified structures included the transverse carpal ligament, flexor pollicis longus tendon, second flexor digitorum superficialis tendon, carpal bones and ligaments, and the MN.The MN was observed in 31.9% of 94 wrists (95% CI: 23.4∼41.9%)and occupied 22±0.13% of PC7 width (95% CI: 18∼27%) when present.The optimal zone for MN stimulation was within the PL-side 27% of PC7 width, extending from the PL tendon (0 mm) to 1.03∼1.61mm laterally (95% CI).The PB appeared in 17% of wrists, positioned 33±23% (95% CI: 23∼45%) from the PL side, at 0.74∼1.47mm.Thus, the safe zone for MN stimulation avoiding PB injury was limited to 0∼0.74 mm from the PL tendon.Conclusions : PC7 encompasses multiple anatomical targets, including the MN.The Ultrasonography: PC7 and Median Nerve KOREAN JOURNAL OF ACUPUNCTURE MN occupies a narrow region in a minority of individuals, suggesting PC7 is generally safe for non-MN-related needling.For intentional MN stimulation, its limited distribution and frequent PB presence may restrict safety and precision.Alternative approaches, such as medial needling relative to the PL tendon, warrant further investigation.