Masters Degrees (Anatomy and Histology)

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Browsing Masters Degrees (Anatomy and Histology) by Subject "Bifurcation theory"

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    Anatomical variation of the carotid bifurcation in a Stellenbosch University cadaver cohort
    (Stellenbosch : Stellenbosch University, 2019-04) Dreyer, Rita Liezl; Page, Benedict; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Anatomy and Histology.
    ENGLISH ABSTRACT: The carotid bifurcation is the point where the common carotid artery bifurcates into the internal and external carotid artery. A precise anatomical knowledge of the carotid bifurcation is required for various medical specialities. The anatomy of the carotid bifurcation influences the risks, location and prognosis of related pathology. Furthermore, the anatomy of the carotid bifurcation affects treatment as it determines which surgical techniques can be used in an area of high risk. The aim of the study was to determine the anatomical variations of the carotid bifurcation in a Stellenbosch cadaver cohort. One hundred and twenty-eight specimens were examined. This research focuses on the height, angle, general structure, and diameters of the carotid bifurcation, as well as the length and diameter of the carotid sinus. The internal anatomical variation of the carotid bifurcation was added as the study progressed. This study used the gonion as the landmark when measuring height. The Stellenbosch cadaver cohort had a high frequency of high bifurcation with the mean distance of 2.12 cm on the right and 2.06 cm on the left. The angle of bifurcation was 18.53° on the right and 20.24° on the left and was smaller than previous reports in the literature, which ranged between 51-67°. Females had a higher bifurcation and larger angle of bifurcation than males. Sex affected the correlation between angle and height of the bifurcation. The general structure correlated with the standard description and was not influenced by other factors pertaining to the carotid bifurcation, sex or age. Kinks were found in the internal and external carotid artery. The diameters of the carotid bifurcation were larger on the left than on the right. The height of the bifurcation did not influence the probability of kinks in this study, contrary to the literature. The diameters of the internal, external and common carotid arteries in addition to the carotid sinus diameter were larger on the left side and in males. The external carotid had the weakest correlation with the other diameters, which was due to the external carotid artery’s embryological origin. The length of the carotid sinus was 1.74 cm on the right and 1.83 cm on the left. The diameters and the length of the carotid sinus was larger in the males. All external variation slightly increased with age over time as the elasticity of arteries decreased. A variation of the flow diverter was observed in 59% of the cadaver cohort. Supplementary flow diverters were a rare abnormality observed in the internal, external and common carotid arteries. The reason for the carotid bifurcation to present with supplementary flow diverters is still up for debate as this has not been observed in living patients; however, a pathological origin was suggested. Folds in the common carotid were observed. Internal anatomical variation was not affected by external variation or age; however, men had a higher probability of presenting with variation. The Stellenbosch cadaver cohort illustrated variations in the carotid bifurcation which was population-specific. Sex influenced various aspects and correlations of the carotid bifurcation, which means discrepancies can occur and should be considered. Further studies on the carotid bifurcation are needed.
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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.