Aortic arch origin of the vertebral artery may have clinical implications

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Ethnic differences in the morphology of the pinna

Metric features of the ear are important for diagnosis of congenital malformations, pre-operative planning and design of hearing devices. Non-metric features including earlobe attachment is a marker of population genetics. Although these features vary with sex and populations, it’s unclear whether they show ethnic variations. This study describes ethnic differences in the morphology of the pinna. Both ears of one hundred and forty-eight (148) medical students (80males and 68 females) [recruited from four ethnic groups: Kenyan Indian, Kenyan Arab, Kikuyu and Luhya] were studied. Ear projection, heights and widths of ear, earlobe and concha were measured. For the Kenyan Indians, Arabs, Kikuyus and Luhyas respectively, proportion of free earlobes was 70.1%, 48.6%, 37.8%, 43.2%, attached lobes was 21.6% 27.1%, 42.9%, 32.4%. Mean earlobe height was 18.2mm, 16.7mm, 15.8mm, 15.8mm (p=0.001), ear projection at mid-tragus was 14.5mm, 13.5mm, 12.5mm, 12.6mm (p=0.035). Ethnic differences are present in earlobe height, attachment type and ear projection at mid-tragus. Earlobe height among indigenous Kenyans is significantly smaller compared to Kenyan Indians and Arabs. The attached earlobe is most prevalent among Kenyan indigenous while the free earlobe is most prevalent among Kenyan Indians. These features ought to be considered in aesthetic reconstruction of ear during earlobe rejuvenation and correction of projected ears.Keywords: Pinna morphology, Ethnic difference, Variation

Non muscle cells in the tunica media of the aorta

Knowledge of cellular composition of aortic tunica media is important to improve understanding of aortic pathology. The aorta of 6 healthy male goats was studied by electron microscopy to elucidate cell types within the tunica media. Glutaraldehyde fixed specimens were processed for durcupan embedding and sectioning, stained with uranyl acetate, counterstained with lead citrate and ultrathin sections examined at high magnification. Two non muscle cells were observed, one resembling fibroblasts and the other with features of macrophages. It is concluded that these cells are normal constituents of the aortic media, involved in synthesis of extracellular matrix and immunosurveillance respectively. Their involvement in repair and disease process needs further investigation.Keywords: tunica media, aorta, fibroblast, macrophage

Physical and emotional impact of dissection: findings from a pioneer medical class in a Kenyan Medical School

Cadaver dissection is a significant life experience, and constitutes a potential stressor in medical education, with attendant physical and psychological effects. However, these effects have mostly been studied in established medical schools. We sought to determine the physical and emotional impact of cadaver dissection among medical students in a pioneer class. We administered two questionnaires: one on the first day of dissection, and the second six weeks later. Each examined the symptoms of cadaver exposure, and the emotional impact using the Appraisal of Life Events (ALE) scale, which measures the scores for challenge, threat and loss. The commonest symptoms reported were nausea, fear (with palpitations) and restlessness. Female students reported more symptoms compared to male students. Most symptoms reduced significantly after six weeks. In conclusion, we found that the dissection experience is challenging and stimulating to most students, as evidenced by higher ALE scores for challenge factor compared to threat and loss. We conclude that dissection, though physically exerting to students, is not considered and averse experience. The gender differences underlie the need for gender-tailored pre-dissection preparation and counselling.Keywords: Cadaver, Dissection, Symptoms, Psychological, Appraisal of Life Event

Gender difference in the modified Insall-Salvati ratio in a black Kenyan population

The patellar tendon (PT) is part of the extensor mechanism of the knee attaching to the apex of the patella and tibial tuberosity. Gender differences of the PT have been described in terms of response to tensile forces. This response may be influenced by the patella height. An index for assessment of patellar height is the modified Insall-Salvati ratio. This ratio is used to classify the patella as either high riding (alta) or low riding (baja). Patella alta has been correlated to chronic patellar tendinopathy. Patellar tendinopathy is more common in males (6:1). The hypothesis of the study was that males would have a higher ratio and there was an expectation of more cases of patella alta among males. One hundred and two pairs of patellar tendons (58 male, 44 female) were thus obtained by simple random sampling from postmortem specimens at the Kenyatta National Hospital and Nairobi City mortuary. All the patellar tendons and patella bones were used to study the modified Insall-Salvati ratio, using a digital vernier caliper. This ratio was determined by dividing the length of the posterior lamina of the patellar tendon with the maximum diagonal length of the patella. The mean of the modified Insall-Salvati ratio for the right was 1.201 +/- 0.0901 in females and 1.1275 +/- 0.133 in males, p=0.001. The mean of the modified Insall-Salvati ratio for the left was 1.206 +/- 0.085 in females and 1.132 +/- 0.123 in males, p=0.001. Therefore, using the cut off value of 2.0, no cases of patella alta were observed. The modified Insall- Salvati ratio was thus observed to be higher in females in the Kenyan population. This observation of disparity between the expected and the observed results is confounding yet similar and consistent with previous findings in other populations. Research on the prevalence of patellar tendinopathy in the Kenyan population and radiological determination of the modified Insall-Salvati ratio is recommended.Keywords: Modified Insall-Salvati ratio, black Kenyan population

Regional differences in the cellularity and vascularity of the patellar tendon

The patellar tendon (PT) attaches to the apex of the patella and  tibial tuberosity. Its response to tensile forces is influenced by the distribution of fibroblasts and its vascularity. The vascularity and distribution of fibroblasts influence the tendons ability to repair microtears. Microtears of the PT result in patellar tendinopathy. There is however, paucity of data on the regional distribution of vascular and cellular elements in the PT which might explain why microtears occur in the posterior-proximal third. One hundred and two pairs of patellar tendons were obtained from postmortem  specimens. Sections from the proximal, middle and distal third from the anterior and posterior lamina of 20 pairs of the patellar tendon (10 male, 10 female) were processed for microscopy to demonstrate the cellularity and vascularity of the tendon. The vascularity was highest in the middle third of the anterior lamina. The posterior lamina of the tendon was less vascular than the anterior lamina. The posterior lamina was more cellular than the anterior with the proximal third showing the highest number of nuclei. These findings indicate that the pre-patellar genicular anastomosis contributes significantly to the vascularity of the anterior lamina while the anastomosis located in Hoffa’s fat pad may be less rich and thus resulting in lower vascularity for the posterior lamina. Lower vascularity implies less healing ability after microtears. Therefore, orthopedic surgeons should be aware of this precarious pattern of vascularity to the posterior lamina. The posterior lamina’s high cellularity especially in the proximal third indicates that it may experience greater stress and via  durotaxis more fibroblasts migrate to that region to produce more collagen fibers for resilience. The greater tensile stress  experienced by the posterior-proximal third and its lower  vascularity may explain why it is most susceptible to microtears.Key words: Patella tendon, regional differences, cellularity, vascularity, patella tendinopath

Involvement of multiple cell lineages in atherogenesis

Atherogenesis is a multicellular event. Early reports concentrated on the role of endotheliocytes, monocyte - macrophages and smooth muscle cells. Recognition of the immuno-inflammatory nature of the process, however, expanded the scope of cellular involvement and more recent reviews emphasize the role of immune and inflammatory cells. In addition, recent studies reveal that other cells are also involved. Elucidation of all the types of cells involved is valuable to inform therapeutic interventions for this disease, but most accounts concentrate on cells which are the target of the study and may fail to include other cells. This review therefore aimed at consolidating information on the various cells involved in atherogenesis. Review of contemporary literature was done for cells in the vessel wall and in blood to check for their potential role in atherogenesis. It has been shown that atherogenesis involves all the cells present in the various coats of the vessel wall – endotheliocytes, smooth muscle cells, fibroblasts, stem cells, pericytes, mast cells, dendritic cells, macrophages and immigrant cells usually found in blood, namely monocytes, neutrophils, lymphocytes, platelets and red blood cells. These cells promote atherogenesis by secreting several products which influence inflammation, migration, proliferation and secretory activity of each other in a manner that synergises their activities. Therapeutic interventions should target the various cell types.Key Words: Cells, arterial wall, blood, atherogenesis

Tunica Adventitia of the Aorta is an Active Vascular Compartment

The tunica adventitia has previously been regarded as a passive connective tissue covering that offers only nutritive and physical support to the arterial wall. Recently, however, emphasis has been given to its role in atherosclerosis. Although the normal structure may bear the anatomical basis of these functions, microscopic anatomy of the tunica adventitia in normal arteries is seldom reported. These data are important in understanding disease process and potential areas of intervention. The goat is a suitable model for studying cardiovascular disease and the aorta is frequently afflicted by atherosclerosis. This study, therefore, aimed at describing the structure of tunica adventitia of normal aorta in goat. Materials for the study were obtained from abdominal aorta of 6 healthy young adult male goats (capra hircus) age range 12 – 24 months. Fresh specimens from euthanized animals were fixed in 3% phosphate buffered glutaraldehyde, post fixed in 1% phosphate buffered osmium tetroxide then embedded in durcupan. Ultrathin sections were stained with uranyl acetate counterstained with lead citrate and examined with electron microscope. Some specimens were processed routinely for paraffin embedding and sectioning. They were stained with Mason’s Trichrome and Weigert elastic/Van Gieson stains. The tunica adventitia was fibroelastic with numerous capillaries, arterioles and multiple cell types. The cells were active fibroblasts, phagocytic, perivascular and endothelial cells embedded in the fibrous stroma. These findings suggest that the tunica adventitia of the goat aorta is a metabolically active vascular compartment. These features namely microvasculature and multiple cell populations probably enable it to maintain structural and functional integrity and appropriately respond to vascular injury.Keywords: Tunica Adventitia, cells, Capillaries, Arterioles, Atherosclerosi

Reappraisal of the structure of arterial Tunica adventitia and its involvement in atherosclerosis

Tunica adventitia was previously considered an inert fibrous layer only involved in nutritional and physical support of the arterial wall. Recent studies reveal that it is an important dynamic layer actively involved in the regulation of vascular structure, function, response to injury and disease processes especially atherosclerosis. Many anatomical studies on arteries, however, still make only peripheral reference to it, without elucidating its detailed structure. Knowledge of the latter is important in understanding pathobiology and interventional approaches to atherosclerosis. This review, therefore, aims at consolidating contemporary literature on the structure and clinical significance of the arterial tunica adventitia. Google literature search was done using the key words tunica adventitia combined with: artery, aorta, cells, cell types, collagen, elastic fibres, vasa vasora, lymphatics, nerves, atherosclerosis. There is overwhelming evidence that the tunica adventitia comprises multiple types of collagen and elastic fibres arranged in various directions, a wide variety of cells including fibroblasts, smooth muscle, pericytes,  myofibroblasts, leukocytes, mononuclear phagocytic, defence, mesenchymal stem and mast cells; vasa vasora including  microvasculature, lymphatics and neural elements. The exact cellular, fibre composition and orientation vary between various arteries and regions of the same vessel. Its components are involved in the initiation, progression and complications of  atherosclerosis. In conclusion, the tunica adventitia is an active dynamic layer which, besides mechanical and nutritive  functions; has metabolic, regulatory and defence roles that are critical in arterial homeostasis and  atherosclerosis. Vascular studies should always include detailed analysis of the biology of the tunica adventitia.Key words: Tunica adventitia, cells, fibres, vessels, nerves, atherosclerosi

Morphometry of the osteodural bridge and the myodural bridge of the rectus capitis posterior major in a black Kenyan population

The connective tissue between the rectus capitis posterior major and the cervical dura, popularly known as the myodural bridge has been postulated to contribute to dural tension monitoring. It prevents dural enfolding thus preventing stimulation of dural nociceptors which would result in cervicogenic headaches. Its length may be an indicator of its effectiveness; however, determination of its length radiographically is difficult. The osteodural bridge, the connective tissue between the axis and dura can be measured radiographically. The aim of the study was therefore to determine if there is a relationship between their lengths. Thirty formalin fixed cadavers were meticulously dissected at the department of Human Anatomy, University of Nairobi, to expose the suboccipital triangle. The lengths of the bridges were measured using a pair of digital vernier caliper. The data was recorded, coded and analyzed using Statistical Package for Social Sciences (SPSS) version 21.0. The means and standard deviations were determined. Histograms and probability plots were generated to determine the normality of the data. A Pearson’s correlation coefficient was generated to determine a correlation between the length of the myodural bridge and osteodural bridge. Of the 30 cadavers dissected, all had the myodural bridge and Osteodural bridge present. The mean length of the myodural bridge was 4.02+/- 0.395 mm. Mean length of the osteodural bridge was 2.71 +/- 0.311 mm. There was a linear relationship of the equation y=1.02x + 1.26 (R2 =0.640). The length of the osteodural bridge may be used as a predictor of the myodural bridge’s length.Keywords: Myodural, Rectus Capitis Posterior Majo