Clinical Anatomy Study On Femoral Nerve Block:A Comparison Of Sheet Plastination And Ultrasound Images

Objective(1)To reveal the hierarchical structure of the fascia covering the anterior of the femoral nerve at the lever for the femoral nerve block,and to clarify the barrier function of the fascia to local anesthetics.(2)Using three-dimensional visualization tools and sheet plastination slices to reconstruct the threedimensional model of the fascia around the femoral nerve,providing vivid anatomic image information for clinician and anesthesiologist.Methods(1)Six adult pelvic specimens were selected,of which three were used for sectional anatomy and three were for layer-by-layer dissection observation;(2)Four sets of transverse sections from 4 cadavers were used in the sheet plastination study;(3)Located the series slices corresponding to the operation lever of the femoral nerve block,and used the Amira 6.0? software to reconstruct the fascia of this region;(4)The femoral nerve block operational ultrasound images form 36 cases were collected and compared with sheet plastination images;(5)According to the results of previous experiments,we redesigned the approach of femoral nerve block and observed the barrier function of the connective tissues to the local anesthetic.Results 1.Gross anatomy results:(1)The femoral nerve lay on the surface of the iliopsoas,and the iliac fascia closely covered the femoral nerve.Posterolateral of the femoral artery,the iliac fascia was involved in the posterolateral wall of the femoral sheath,which was not seen to form a membrane sheath encircling the femoral nerve.(2)On the medial border of the sartorius,two layers of fascia on the upper and lower surface of the sartorius merged to be the fascia lata.Then the fascia lata went forward to the anterior wall of the femoral sheath.(3)Two bundle connective tissues attached to the lateral and medial of the epineurium of the femoral nerve.(4)The femoral artery sent out the deep femoral artery at 3.0~3.9 cm(mean 3.5cm)below the midpoint of the inguinal ligament.The femoral nerve branched at a distance of 1.0~2.1cm(an average of 1.4cm)above the femoral artery bifurcation.2.Sheet plastination results show:(1)At the corresponding level of the femoral nerve block,the iliac fascia closely covered the femoral nerve and continued to the posterolateral wall of the femoral sheath on the medial side.The iliac fascia did not develop a sheath-like structure surrounding the femoral nerve.(2)The fascia lata traveled inwardly from the surface of sartorius muscle to the anterior wall of the femoral sheath,covering the iliac fascia,femoral nerve,iliopsoas muscle and femoral sheath.Among the four specimens(8 sides),the double layers of fascia lata did not unite in the medial border of the sartorius muscle in six sides.But it merged into a single layer in the remaining two sides.(3)In four specimens,dense connective tissues were observed on both sides of the femoral nerve.3.Sheet plastination slices could show the fascia structure,and images could be used to create a threedimensional model by Amira 6.0? software.4.Sheet plastination slices and ultrasound imaging contrast:(1)Ultrasound images showed that the surrounding fascia of femoral nerve was similar to the plastination slice;(2)The iliac fascia was a white hyperechoic cord-like line,located in front of the femoral nerve and closely adjacent to the femoral nerve.(3)The fascia lata covered the femoral nerve,iliac fascia,and femoral sheath,which were far away from the femoral nerve.In 36 cases of ultrasound images,30 cases showed double layers,while 6 cases showed one layer.5.The dense connective tissues on both sides of the femoral nerve had a barrier effect on local anesthetics.Conclusions 1.The iliac fascia is closely related to the femoral nerve and can be utilized as the localization mark of ultrasound-guided femoral nerve block.2.The lateral and medial attachment of the femoral nerve can limit local anesthetic diffusion.