Anatomical characterization of acupoint large intestine 4

Large intestine 4 (LI4) is a major acupoint used in various treatments in acupuncture and Traditional Chinese Medicine. There are structures associated within the region of LI4 that have three-dimensional anatomical relationship that needs further characterization. The aims of this study were: (a) to observe the anatomical variation of structures around LI4; (b) to observe specific overlap of structures around LI4. A 1256 mm² area was dissected in 25 cadaveric hands around LI4. Nondissected areas were marked with pins as reference points. Dissections were photographed with a fixed camera. Subsequently, images were imported to Adobe Photoshop 2020 and analyzed. Descriptive statistics and graphs were compiled using Graphpad Prism 2020. The tributaries of the dorsal venous plexus (22.3%), branches of superficial radial nerve (18.9%), first dorsal interosseous muscle (52.4%), arterial branches in the first interosseous space (10.2%), and deep ulnar nerve (4.0%) were observed in the area of LI4. One branch of the superficial radial nerve passed through LI4. The deep ulnar nerve was found in the bulk of the first dorsal interosseous muscle. Several structures observed intersected at LI4. The superficial radial nerve interweaved with the dorsal venous plexus superficially. The deep ulnar nerve passed anterior to the second palmar metacarpal artery before entering into the first dorsal interosseous muscle. These results provide anatomical evidence and variation into the vascular contributions at LI4.