Anatomical And Imaging Observation Of The Femoral Fascia Sheath And Its Surrounding Structures

Objective The aims of this study were to investigate the anatomical relationship amongthe femoral nerve, the fascia iliaca and their adjacent structures; to examine theappearance of the femoral nerve and its surrounding fascia under the ultrasound, theMRI and the plastination slice, to determine whether a femoral nerve “sheath” existsand to provide anatomic basis for the lower limb nerve block.Methods (1) Cadaveric study: Ten sides of lumbar and thigh regions from5formalin-fixed cadavers were used in this study. All of the specimens were injected withlatex using a step-by-step injection method from the distal to the proximal and dissectedfor topographic anatomy examination. Injection was the mixture of gelatin with blackink instead of the latex. The tissue blocks were removed, paraffin-embedded andsectioned. The sections were stained with hematoxylin eosin. One adult cadaver and twofetus cadavers were prepared for plastination. The cadavers were embedded in10%gelatin solution and frozen at-80°C to make a gelatine block. The blocks weresectioned horizontally in a thickness of2.5mm by a butcher’s bandsaw and the cuttingsurfaces of slices were cleaned with tap water. The slices were dehydrated, degreased,impregnated and cured.(2) Study of the living subject: Two patients were undergo“3-to-1”block and three patients were undergo fascia iliaca compartment block. Theblock was undertaken with the ultrasound guidance. MRI of the inguinal area to the firstlumbar vertebra was performed in three patients. Result1. An intact femoral nerve “fascial sheath” was not observed in the specimensexamined in this study.2. The femoral nerve was surrounded by various fascia-likestructures. From the proximal to the distal, those fascia-like structures were the fascia oflumbar plexus, fascial septum of the psoas, the fascia iliaca and some loose fat tissuecovering the femoral nerve.3. The femoral nerve was surrounded by fibers in the psoasmuscle. The fascia iliaca and some adipose tissue covered but not enveloped the femoralnerve out of the psoas muscle,4. The femoral nerve was appeared as triangular orirregular area with white high echo signal, the iliac fascia was appeared as long stripedwith white high echo signal undergo the ultrasound guidance. The anatomicalrelationship of the femoral nerve, the psoas muscle, the iliacus and the iliac fascia canclearly showed by the T2W1of MRI, and consistent with the cross-sectional specimen.Conclusion1. An intact femoral nerve “fascial sheath” was not observed in thespecimens, suggesting that the anatomical basis of the “3to1”block may not be solid aswhat we believe before. The iliac fascia block appears safer and more anesthesia andanalgesia.2.The anatomical relationship among the femoral nerve, the iliac fascia andtheir adjacent structures is demonstrated in this study by the local anatomy, the sectionalanatomy, the thin-layer plastination, the ultrasound and the MRI, which provides theanatomical basis to enhance the success rate of the block.3. The E12plastinationmethod allows superb visual clarity. The plastinated sections allow visualization ofgross structures as well as microscopic structures, providing a powerful research tool forthe fascia study.