Anatomy and Histology

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Browsing Anatomy and Histology by Subject "Anatomy"

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    Clinical implications of the variations of sciatic nerve bifurcation on the popliteal nerve block
    (Stellenbosch : Stellenbosch University, 2018-12) Mady-Goma, Chancy Rosine; Tchokonte-Nana, Venant; Stellenbosch University. Faculty of Health and Medical Sciences. Dept. of Biomedical Sciences. Anatomy and Histology.
    ENGLISH ABSTRACT: The sciatic nerve (SN) is a major nerve of the lower limb, innervating the posterior thigh, the hip and knee as well as structures below the knee through its branches. The SN division occurs in the popliteal fossa (PF) at the level of the knee. However, various studies report great variations in the level of division of the SN, ranging between 3.3 and 65.1%. These variations were suggested as a possible cause in failures of the popliteal block (PB). Therefore, the aim of this study is to describe the level of division of the SN in a South African cohort and to evaluate the success rate of three approaches to the PB. Following the simulation of the PB in 22 lower limb specimens, the popliteal fossae of 61 cadavers were dissected and the sciatic nerve properly exposed. The level of division was described and the location and distance between the dye and the nerve measured. Variations represented only 11.48% of cases, similar to textbooks’ description (12%). The bifurcation pattern of the SN in this South African cohort was therefore comparable to the standard one. The distance between the SN and the PC varied between 20 mm and 405 mm, with a median of 55 mm, close to 60 – 70 mm found in most studies. The prevalence of variations was higher in females (ratio F:M=2.78) and 55.56% were bilateral. With the SN dividing in the PF, the simulation predicted a 100% success rate with no difference between the approaches used. Nevertheless, a higher division of the SN would compromise the success of the block. Overall, the SN division in our study population follows the normal pattern with a lesser degree of variations (11.48%). The division of the nerve in the PF might ensure a successful block in 95 to 100% of cases, in contrast to cases of high variations. Nevertheless, a preoperative imagery is strongly recommended, especially in women for early identification of variations to avoid failures of the PB, irrespective of the approach used.
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    The sciatic nerve division in the gluteal region in a South African population: An anatomical study
    (Stellenbosch : Stellenbosch University, 2019-04) Bergsteedt, Bryan Jason; Greyling, L. M.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Anatomy and Histology.
    ENGLISH ABSTRACT: The sciatic nerve is repeatedly involved in the daily medical practices of anaesthesia, neurology, orthopaedics and rehabilitative medicine. The sciatic nerve, and its branches, are some of the most frequently injured nerves within the human body. A possible reason for injury could be related to an inadequate knowledge of the anatomical variations of this nerve. Adequate understanding of the anatomical variability within the gluteal region is vital for appropriate diagnosis, potential treatment of gluteal pathology and pain and population-specific anomalies. To the author’s best knowledge, no previous study has described the anatomical variations in relation to the piriformis and sciatic nerve bifurcation within the South African population. Therefore, the aim of the study is to report the prevalence of anatomical variations within the course of the sciatic nerve in relation to the piriformis muscle. Additionally, to report the prevalence of the variations in the level of the sciatic nerve bifurcation. Lastly, to analyse the typical sciatic nerve and piriformis morphomety. The results obtained will be a comparison between sides, sexes, and population groups. For the purpose of this study, lower limbs (𝑁=340) from 170 South African cadavers were selected for dissection and morphological analysis. These specimens consisted of 191 males and 149 females, and comprised of three South African subpopulation groups, namely, White/Caucasian (𝑛=232), Mixed race (𝑛=78) and South African Black (𝑛=30). The variations were recorded, classified and described. Piriformis and sciatic nerve parameters were measured morphometrically using a digital sliding calliper, and statistically analysed. Analysis of the relationship between piriformis and the sciatic nerve resulted in 43 (12.65%) specimens that presented variations in the morphology, while 297 (87.35%) specimens presented normal anatomical features. Variations of these structures occurred predominantly in the South African White/Caucasian population. The bifurcation of the sciatic nerve occurred mainly in the popliteal fossa proper (79.6%). The width of the sciatic nerve was significantly larger in the White/Caucasian group (𝑝<0.05), in comparison to the other two groups. The mean length of the sciatic nerve was significantly larger in the male specimens (𝑝<0.05) in comparison to the female specimens. It was found that the sciatic nerve commonly entered the gluteal region as a single trunk, through the infra-piriform space, inferior to the piriformis muscle. However, variations in the anatomy of the sciatic nerve are common, and are vital in assessing clinical risk, and avoiding debilitating injury or incorrect pain diagnoses. To maintain best possible clinical practices requires regularly updated clinical skills in relation to accurate and relevant new anatomical knowledge. It is for this reason that studies, such as this one, ensure that vital research contributions are available for best clinical practice. Clear uniform landmarks for morphometric analysis of the sciatic nerve and piriformis needs to be established in order to create uniformity and understanding of results. Additionally, there is a need for the increase in published literature for the South African subpopulation groups in order to strengthen comparisons and conclusions of reported research. Researchers also need to research variations in larger groups within the South African population.