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Title: Topographic anatomy of the tibial nerve bifurcation and its medial calcaneal branches. Macro and microscopic analysis
Abstract:
Introduction The tibial nerve arises as a branch of sciatic nerves bifurcation in the popliteal fossa. It runs distally on the tibialis posterior muscle together with the posterior tibial vessels. Usually at the level of flexor retinaculum it terminally divides into lateral and medial plantar nerve. During distal course the tibial nerve emits medial calcaneal branch(es) which is variable in number and origin. Tibial nerve and its branches provides innervation to the posterior lower leg, foot and sole muscles and the skin of medial foot and sole. Tarsal tunnel syndrome is one of the entrapment conditions affecting the tibial nerve and its terminal branches in the medial ankle. It causes heel and sole burning pain and paresthesia. Such disorders may be examined by the ultrasound. For many years ankle arthroscopy has proved to be a useful diagnostic and therapeutic procedure for ankle and foot disorders. Although it is a minimally invasive surgery neurological complications are most frequently reported. In order to avoid iatrogenic injuries and to perform safe and reproducible arthroscopy knowledge of topographic anatomy is of vital importance. Methods In the first stage of the study the ultrasound examination was conducted on 30 volunteers (n=60 lower limbs). It was performed on the Mylab Gold 25 ultrasound scanner with a 18MHz linear probe by the orthopedic surgeon with more ; than 20 years of experience in ultrasound examination. The tibial nerve, its bifurcation point, the medial plantar nerve, the lateral plantar nerve and the medial calcaneal branches origin were marked on the skin. Then two parallel reference lines were drawn: first crossing the tip of the medial malleolus, second crossing the posterior superior tip of the calcaneal tuberosity. Distances from the reference lines to the tibial nerve bifurcation line and to the medial calcaneal branches origin lines were measured with the caliper. Medial calcaneal branches were also analyzed with regards to the number of branches and nerve of origin. Second part of the study was conducted on 60 lower limbs of the fresh cadavers and on 21 lower legs of the fresh-frozen cadavers. Meticulous dissection revealed the tibial nerve, its bifurcation and lateral and medial plantar nerves which were excised and fixed in a 10% solution of the formaldehyde (pH 7.4). Next each nerve were dehydrated, embedded in paraffin and transverse sectioned on a 2 μm thick slice. Subsequently each slice was stained with haematoxylin and eosin. The cross-sectional area (CSA) and the number of nerve bundles of the tibial nerve, the medial plantar nerve and the lateral plantar nerve were assessed using a light microscope (Olympus BX53, 20 x magnification). Each cross-section was measured semi-automatically using Olympus ce ; llSens Standard 2.3 software whilst the number of nerve bundles was calculated manually. Results In the ultrasound examination the tibial nerve bifurcation occurred below the tip of the medial malleolus (77% cases) with the average distance of 5.9 mm ± 19.59 mm. The medial calcaneal branches were identified in the range from one to three ramifications with the most frequent presentation of a single branch (73% cases) originating from the tibial nerve (60% cases) with the mean distance of 3.97 mm below the tip of the medial malleolus. In the microscopic examination of the nerves collected from the fresh cadavers the mean CSA and the number of nerve bundles were respectively 15.25 ± 4.6 mm2, 30.35 ± 8.45 for the tibial nerve, 8.76 ± 1.93 mm2, 20.75 ± 7.04 for the medial plantar nerve and 6.54 ± 2.02 mm2, 13.40 ± 5.22 for the lateral plantar nerve. In the fresh-frozen cadavers group the mean CSA and the number of nerve bundles were respectively 13.71 ± 5.66 mm2, 28.57 ± 8.00 for the tibial nerve, 7.55 ± 3.25 mm2, 18.00 ± 6.72 for the medial plantar nerve and 4.29 ± 1.93 mm2, 11.33 ± 1.93 for the lateral plantar nerve. Both CSA and number of nerve bundles of the tibial, medial plantar and lateral plantar nerves revealed no statistical differences when comparing foot side of the individual. The statistical difference was related to the gender showing significant bigger CSA and n ; umber of nerve bundles in males. A positive correlation was found between the donors age and the tibial nerve CSA (r = 0.44, p = 0.000). A significant statistical difference was found between the medial and lateral plantar nerves both in CSA and number of nerve bundles ( p < 0.001, p < 0.001 respectively). When comparing nerves collected from the fresh and fresh-frozen only lateral plantar nerves showed statistical differences in the CSA and the number of nerve bundles (p = 0.000, p = 0.037 respectively). Conclusions 1. The tibial nerve and its terminal branches presents anatomical variability in the medial ankle area. 2. The origin, location and division pattern of the medial calcaneal branch(es) presents anatomical variability. 3. The CSA and the number of nerve bundles of the tibial, medial plantar and lateral plantar nerves are significantly bigger in males. 4. The medial plantar nerve has larger CSA and more nerve bundles than the lateral plantar nerve. 5. The tibial nerve shows increasing CSA with advanced age. 6. Histological structure of the larger nerves remains uninfluenced by the freezing process.
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Last modified:
Oct 3, 2023
In our library since:
May 23, 2022
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http://dl.cm-uj.krakow.pl:8080/publication/4681
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| Edition name | Date |
|---|---|
| ZB-133505 | Oct 3, 2023 |
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