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The posterior communicating artery (PcomA), P1 and P2 segments of the posterior cerebral arteries (PCAs) give rise to numerous small branches that chiefly supply the thalamus and midbrain. Thalamic vascular supply is classically categorized into four regions: anterior, paramedian, infero-lateral and posterior. Despite significant variations and overlap in the blood supply, this traditional classification helps in understanding the vascular anatomy of the thalamus. Gerard Percheron extensively studied thalamic blood supply and described its anatomical variants depending on its origin. The artery of Percheron (AOP) is a rare anatomical variation of paramedian-mesencephalic arterial supply in which a solitary arterial trunk arises from the PCA and distributes bilaterally to both paramedian thalami and often to the rostral part of the midbrain. During routine dissection of the brain of a 46-year-old female in the department of anatomy, it was seen that thalamo-perforating artery (AOP) took origin as a single trunk from the P1 segment of the left PCA. The specimen was dissected and photographed for documentation and to see more details. The exact prevalence of AOP remains unknown, but various studies show that it can be present in 7% to 11.7% of subjects. Detailed knowledge of AOP anatomical variation is crucial for interpreting neuroimaging results or performing different neuro-endovascular techniques at the basilar bifurcation, particularly in patients with bilateral thalamic and midbrain infarctions.
RESUMO
Background Multiple choice questions (MCQ) are used nowadays in summative assessments for certification of courses, in a competitive examination, and for recruitment. A single-best-answer stem-type MCQ is one of the formats most commonly used for this purpose; it contains a question and options from which the examinee needs to select the correct answer. Item analysis is used for the determination of the quality, validity, and reliability of the MCQ. Item difficulty index, item discrimination power, and distractor effectiveness are critical for the quality of the MCQs. Aim This study was conducted to estimate the effect of distractor effectiveness on the item difficulty index and item discriminating power. Method A test paper consisting of 200 single-best-answer stem-type MCQs with four options responded to by 400 medical undergraduates was analyzed for item difficulty index, item discriminating power, and distractor effectiveness with established item analysis formulas. The effect of distractor effectiveness on item difficulty index and item discriminating power was statistically analyzed using Epi-Info 7TM software. Result The mean item difficulty index, item discriminating power, and distractor effectiveness were 57.75% ± 28.65%, 0.4388 ± 0.36, and 84.17%, respectively (p<0.05). The item difficulty index was higher for items with single-functioning distractors in comparison to items with three-functioning distractors. Item discriminating power was higher in items with three functioning distractors in comparison to items with one and two functioning distractors. Conclusion Two or three functioning distractors show an appropriate item difficulty index and item discriminating power. In addition, item discriminating power is lower for the easy MCQs. Two to three distractors are appropriate to construct a quality MCQ.
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Introduction Virtual interactive three-dimensional model (VI3DM) is an emerging technology with promising futures in medical education. It allows learners to view and interact with the three-dimensional (3D) object in an isolated virtual environment, as well as on screen-based platforms. This technology seems more helpful in understanding the learning objectives that demand high cognitive and visuospatial skills. The sacrum, part of the posterior wall of the bony pelvis, is a structure of interest to medical professionals and forensic experts. Understanding the anatomy and relations of the sacrum demands good spatial understanding. Hypothetically, virtual 3D models should help in learning the anatomy of the sacrum along with its relations and attachments. This study was conducted to find out the effect of low-cost digital 3D models on the anatomical knowledge of the study. Aims and objectives The goal of the work was to identify the role of virtual 3D models in the conceptualization of the anatomy of the sacrum. The study's objectives were to identify the impact of virtual 3D models on students' knowledge of the external features, relations, attachments, and joints formed by the sacrum. Material and methods Two hundred first-year medical students (168 males and 32 females) who participated in the study after providing informed consent were divided into two equal groups, a control group (n=100) and an experimental group (n=100), after matching the age, gender, and anatomical knowledge of the sacrum. We used two-dimensional (2D) images and virtual interactive 3D models of the sacrum as control and intervention, respectively, in this randomized controlled study. We conducted a post-test quiz after the 30-minute session of self-directed learning. Results The mean difference between the post-test score and the pre-test score of the experimental group (4.1±1.6 ) was significantly higher than the difference between the post-test and pre-test scores of the control group (2.5±1.2). The virtual interactive 3D model of the sacrum was significantly effective in the conceptualization of the sacrum anatomy. Conclusion A virtual interactive 3D model is an effective tool to conceptualize the anatomy of the sacrum and can be explored for its use in further complex anatomical structures. Digital 3D models can become a platform for the application of various virtual realities (VR) and artificial intelligences in medical education.
