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BACKGROUND/PURPOSE: A Stafne bone cavity (SBC) is an incidental depression in the lingual surface of the mandible. The aim of this study is to provide pooled estimates of the frequency of Stafne bone cavity and to correlate its presence with such variables as sex, laterality, diagnostic methods and population. MATERIALS AND METHODS: Potential studies were searched through four electronic databases: Google Scholar, PubMed, Scopus, and Journal Storage. Titles, abstracts, and full texts of the articles were screened. RESULTS: A total of 54 studies relating to 355,890 subjects met the inclusion criteria for meta-analysis. A meta-analysis using the DerSimonian-Laird model revealed an overall prevalence of 0.17% (CI:0.14%–0.21%, I(2) = 80.7%). SBC was four times more common in males than females (z = 6.94, P

The uppermost segment of the cervical vertebra or atlas (C1) is a critically important anatomical structure, housing the medulla oblongata and containing the grooves for the C1 spinal nerve and the vertebral vessels. Variations of the C1 vertebra can affect upper spine stability, and morphometric parameters have been reported to differ by population. However, there are few data regarding these parameters in Thais. The use of this bone to predict sex and age has never been reported.This study aimed to examine C1 morphometry and determine its ability to predict sex. Twelve diameter parameters were taken from the C1 vertebrae of identified skeletons (n = 104, males [n, 54], females [n, 50]). Correlation analysis was also performed for sex and age, which were predicted using machine learning algorithms.The results showed that 8 of the 12 measured parameters were significantly longer in the male atlas (p 0.05), while the remaining 4 (distance between both medial-most edges of the transverse foramen, transverse dimension of the superior articular surface, frontal plane passing through the canal's midpoint, and anteroposterior dimension of the inferior articular surface) did not differ significantly by sex. There was no statistically significant difference in these parameters on the lateral side. The decision stump classifier was trained on C1 parameters, and the resulting model could predict sex with 82.6% accuracy (root mean square error = 0.38).Assertation of the morphometric parameters of the atlas is important for preoperative assessment, especially for the treatment of atlas dislocation. Our findings also highlighted the potential use of atlas measurements for sex prediction.

Chest computed tomography (CT) has been the preferred imaging modality during the pandemic owing to its sensitivity in detecting COVID-19 infections. Recently, a large number of COVID-19 imaging datasets have been deposited in public databases, leading to rapid advances in COVID-19 research. However, the application of these datasets beyond COVID-19-related research has been little explored. The authors believe that they could be used in anatomical research to elucidate the link between anatomy and disease and to study disease-related alterations to normal anatomy. Therefore, the present study was designed to investigate the prevalence of six well-known anatomical variants in the thorax using open-access CT images obtained from over 1000 Iranian COVID-19 patients aged between 6 and 89 years (60.9% male and 39.1% female). In brief, we found that the azygos lobe, tracheal bronchus, and cardiac bronchus were present in 0.8%, 0.2%, and 0% of the patients, respectively. Variations of the sternum, including sternal foramen, episternal ossicles, and sternalis muscle, were observed in 9.6%, 2.9%, and 1.5%, respectively. We believe anatomists could benefit from using open-access datasets as raw materials for research because these datasets are freely accessible and are abundant, though further research is needed to evaluate the uses of other datasets from different body regions and imaging modalities. Radiologists should also be aware of these common anatomical variants when examining lung CTs, especially since the use of this imaging modality has increased during the pandemic.

Background and Objectives: Anatomical variations in the head, neck and chest are common, and are observed as occasional findings on computed tomography (CT). Although anatomical variations are mostly asymptomatic and do not cause any negative influence on the body function, they may jeopardize diagnosis and may be confused with pathological conditions. The presence of variations may also limit surgical access during tumor removal. The aim of this study was to investigate the prevalence of six anatomical variations—os acromiale, episternal ossicles, cervical rib, Stafne bone cavity, azygos lobe and tracheal bronchus—in an open-access computed tomography dataset obtained from oropharyngeal cancer patients. Materials and Methods: A total of 606 upper-chest and neck computed-tomography scans (79.4% male and 20.6% female) were retrospectively investigated. Sex difference was evaluated using the z-test for two proportions. Results: Os acromiale, episternal ossicles, cervical rib, Stafne bone cavity, azygos lobe, and tracheal bronchus were present in 3.1%, 2.2%, 0.2%, 0%, 0.3% and 0.5%, respectively, of all patients. Os acromiale was identified as meso-acromion in 86.6%, and as pre-acromion in 17.4%, of all acromia. Episternal ossicles were present unilaterally in 58.3%, and bilaterally in 41.7%, of all sterna. Only the cervical rib showed a sex difference in prevalence. Conclusions: awareness of these variations is important for radiologists interpreting head, neck and chest CTs; for example, those of oropharyngeal cancer patients. This study also illustrates the applicability of publicly available datasets in prevalence-based anatomical research. While most of the variations investigated in the present study are well-known, the episternal ossicles are not well explored, and need further investigation.

Porotic hyperostosis (PH) is the expansion of the cranial diploë, generating ‘hair-on-end’ appearance on X-rays. This condition is extremely rare and had a prevalence of 0.08%. It is alternatively known as cribra orbitalia (CO) when the orbital roof is affected. In this study, we describe the gross morphology of two skulls affected by PH and CO. The first skull belonged to a 41-year-old female previously diagnosed with beta thalassemia. The skull was affected by excessive PH and CO. The second skull, belonging to a 35-year-old male diagnosed with unspecified thalassemia, showed PH without CO. The etiology of PH and CO is discussed. In conclusion, PH and CO are extremely rare, and are of significant importance for radiologists and anatomists when interpreting radiographs or encountering unusual gross morphology of the skull.

Posterior compartment of forearm and hand is among the most variable parts of the human body. During a routine dissection, we found two anatomical variants in the right forearm and hand of an 84-year-old male cadaver including the extensor indicis radialis and the extensor medii proprius associated with a fibromuscular slip. Histological analysis using hematoxylin and eosin staining revealed that this unusual fibromuscular slip associated with the extensor medii proprius was composed of dense connective tissue along with small amount of skeletal muscle fibers, and the innervation from the posterior interosseous nerve. Based on the existing literature, a fibromuscular slip associated with a hand extensor tendon on the dorsum of hand has never been reported. Further studies are needed to clarify the evolutionary origin of this structure, although it resembles to a certain extent the dorsometacarpales, a group of muscles that were once present in our mammalian ancestors.

Eleven demonstration activities for an introductory undergraduate chemistry safety session are described. The first two activities are a safety video and a lab tour. All other activities are drawn ...

Background and Objectives: The landmark for neurosurgical approaches to access brain lesion is the pterion. The aim of the present study is to classify and examine the prevalence of all types of pterion variations and perform morphometric measurements from previously defined anthropological landmarks. Materials and methods: One-hundred and twenty-four Thai dried skulls were investigated. Classification and morphometric measurement of the pterion was performed. Machine learning models were also used to interpret the morphometric findings with respect to sex and age estimation. Results: Spheno-parietal type was the most common type (62.1%), followed by epipteric (11.7%), fronto-temporal (5.2%) and stellate (1.2%). Complete synostosis of the pterion suture was present in 18.5% and was only present in males. While most morphometric measurements were similar between males and females, the distances from the pterion center to the mastoid process and to the external occipital protuberance were longer in males. Random forest algorithm could predict sex with 80.7% accuracy (root mean square error = 0.38) when the pterion morphometric data were provided. Correlational analysis indicated that the distances from the pterion center to the anterior aspect of the frontozygomatic suture and to the zygomatic angle were positively correlated with age, which may serve as basis for age estimation in the future. Conclusions: Further studies are needed to explore the use of machine learning in anatomical studies and morphometry-based sex and age estimation. Thorough understanding of the anatomy of the pterion is clinically useful when planning pterional craniotomy, particularly when the position of the pterion may change with age.

Purpose Two most common variations of flexor pollicis longus include its accessory head and its connection with the flexor digitorum profundus of the index (Linburg–Comstock variation). In addition, while three-dimensional (3D) screening has widely been used in anatomical education, its use as reporting tool in anatomical research is still limited. The objective of this study is to report a previously unrecognized form of the accessory head of flexor pollicis longus, discuss the potential etiology of Linburg–Comstock variation, and pilot the 3D scanning of a large-scale anatomical structure. Methods An unusual tendon slip was discovered during a routine dissection in the anterior compartment of the right forearm of a 54-year-old male cadaver. A 3D scanner was used to capture the surface topography of the specimen and an interactive portable document format (PDF) was created. Results An anomalous tendon was found originating from the lateral aspect of the flexor digitorum profundus muscle. This variant tendon then inserted onto the medial surface of the flexor pollicis longus tendon before entering the carpal tunnel. The variation resembles a reverse form of Linburg–Comstock variation, because pulling this variant tendon resulted in simultaneous flexion of the interphalangeal joint of thumb. Conclusion Surgeons should be aware of the reverse Linburg–Comstock variation, because it may not be detectable by the conventional provocative testing. Linburg–Comstock variation may be classified as an anatomical variant or a secondarily acquired condition depending on its type. Our demonstration of interactive 3D-PDF file highlights its potential use for delivering anatomical information in future cadaveric studies. Supplementary Information The online version contains supplementary material available at 10.1007/s00276-021-02858-8.

Forty anatomy articles were sampled from English Wikipedia and assessed quantitatively and qualitatively. Quantitatively, each article's edit history was analyzed by Wikipedia X-tools, references and media were counted manually, and two readability indices were used to evaluate article readability. This analysis revealed that each article was updated 8.3 ± 6.8 times per month, and referenced with 33.5 ± 24.3 sources, such as journal articles and textbooks. Each article contained on average 14.0 ± 7.6 media items. The readability indices including: (1) Flesch-Kincaid Grade Level Readability Test and (2) Flesch Reading Ease Readability Formula demonstrated that the articles had low readability and were more appropriate for college students and above. Qualitatively, the sampled articles were evaluated by experts using a modified DISCERN survey. According to the modified DISCERN, 13 articles (32.5%), 24 articles (60%), 3 articles (7.5%), were rated as "good," "moderate," and "poor," respectively. There were positive correlations between the DISCERN score and the number of edits (r = 0.537), number of editors (r = 0.560), and article length (r = 0.536). Strengths reported by the panel included completeness and coverage in 11 articles (27.5%), anatomical details in 10 articles (25%), and clinical details in 5 articles (12.5%). The panel also noted areas which could be improved, such as providing missing information in 28 articles (70%), inaccuracies in 10 articles (25%), and lack or poor use of images in 17 articles (42.5%). In conclusion, this study revealed that many Wikipedia anatomy articles were difficult to read. Each article's quality was dependent on edit frequency and article length. Learners and students should be cautious when using Wikipedia articles for anatomy education due to these limitations.

The azygos lobe (AL) is an accessory lobe of the right lung with prevalence between 0.4 and 1.2%. The aim of the present review is to provide a better estimate of the frequency of the AL and to examine its relationships with other variables such as population, diagnostic methods, and co-occurring illnesses. Studies published between 1899 and October 2020 were searched through three electronic databases; Google Scholar, PubMed, and JSTOR. Titles, abstracts, and full texts of the retrieved entries were screened to determine their appropriateness for inclusion. A total of 88 studies relating to 1,033,083 subjects met the inclusion criteria. A random-effects meta-analysis yielded an overall prevalence of 0.30% (95% CI: 0.0024-0.0035, I2 = 97.9%). Linear regression and subgroup analysis revealed a negative correlation (ρ = -0.540, p

Introduction Thyroid ima artery is a variant artery found on the anterior surface of the trachea. The aim of this meta-analysis was to obtain pooled prevalence data of the thyroid ima artery and discuss its clinical importance especially for tracheostomy. Methods A systematic literature search was performed through five electronic databases until May 2021. A set of inclusion and exclusion criteria based on AQUA guidelines were used to select relevant studies. Meta-analysis, subgroup analyses, meta-regression, and tests for publication bias were performed. Factors that influence the prevalence of the thyroid ima artery were detected using simple and interpretable machine learning (linear regression and K means). Results Thirty-six studies with a total of 4335 subjects met the inclusion criteria. The prevalence of the thyroid ima artery was 3.8% (95% CI: 0.027−0.049, I2 = 56.2%). Machine learning identified age, region and year of publication as potential covariates. Subgroup analysis showed that the prevalence of the thyroid ima artery was 4.5 times higher in fetuses (14.8%) than adults (3.3%) (z = −6.76, p Conclusion In addition to evidence-based synthesis of the thyroid ima artery, this study is the first ever study to report the decreasing prevalence over time of a human body structure in the postnatal life. Knowledge of the thyroid ima artery is of vital importance for surgeons to avoid accidental hemorrhage during tracheostomy.

Anconeus epitrochlaeris muscle and Osborne's ligament are anatomical variants that are occasionally found at the cubital tunnel of the elbow. In certain individuals, these two structures may compress the ulnar nerve resulting in a cubital tunnel syndrome. Although these variants have been reported extensively, its prevalence is still unclear and its contribution to cubital tunnel syndrome is debatable. The aim of this study is to generate weighted frequency values of the anconeus epitrochlearis and Osborne's ligament, as well as to identify any association of these two structures with gender, side, ethnicity and the development of cubital tunnel syndrome.An anatomical study and a meta-analysis were performed to more accurately study the prevalence of anconeus epitrochlearis and Osborne's ligament. A total of 40 original studies including the present study met the inclusion criteria for meta-analysis and 6 case reports for descriptive analysis.Crude pooled prevalence estimate of the anconeus epitrochlearis was significantly higher (p 0.001) in healthy subjects (14.2%) than in subjects diagnosed with cubital tunnel syndrome (4.5%). No significant difference was found for gender, side or laterality. The anconeus epitrochlearis was significantly more common in Europeans populations (18.2%) when compared with North American (6.8%) (p = 0.012) and Asian populations (7.5%) (p 0.001). Anconeus epitrochlearis had a tendency to be hypertrophied when associated with cubital tunnel syndrome. The definition of Osborne's ligament is unclear, resulting in inconsistent reported prevalence across studies.The present study provides a more accurate estimate of anconeus epitrochlearis across the populations. There was a negative correlation between the presence of anconeus epitrochlearis and the development cubital tunnel syndrome, supporting the idea that the muscle may be protective against cubital tunnel syndrome. Future studies are needed to give proper definition of Osborne's ligament and accurately study its prevalence across populations.

Anatomical variants in the posterior compartment of forearm and hand are not uncommon. Physicians should be aware of variations in this region for correct diagnosis and treatment of diseased hands. During a routine dissection at our department, an extremely rare case of deep hand extensor muscle was discovered. A complete extensor digitorum profundus complex was found in the fourth extensor compartment in addition to the extensor indicis proprius. The complex consisted of two muscle bellies originating from the lateral aspect of distal ulna and the adjacent interosseous membrane. The first belly resembled the conventional extensor indicis proprius. The second belly gave off two tendon slips: one inserted to the index and middle fingers and the other formed aponeurosis before inserting to the ring and little fingers. To our knowledge, a complete extensor digitorum profundus complex which inserts to all medial four digits has never been reported in humans. Awareness of variations in this region is critical for surgeons operating in the forearm and hand. The present case also provides insights into the evolutionary and developmental origin of these structures.

The aim of the study was to investigate the anatomy and histology of Linburg–Comstock variation, or the anomalous connection between flexor pollicis longus and flexor digitorum profundus to the index finger, in Thai population. One hundred and thirty cadaveric upper limbs were dissected. Skin and superficial fascia on the anterior distal forearm and hand were removed. The tendons of the flexor pollicis longus and flexor digitorum profundus to the index finger were identified for the possible occurrence of the intertendinous connection. For histological analysis, selected specimens were sampled, and were stained with hematoxylin and eosin. Out of 130 dissected upper limbs, interconnection between the two tendons was found in 32 limbs (25%). The connection was classified into three types including fibrous, tendinous, and musculotendinous. In 29 cases (22%), the connection was simply the thickening of synovial sheath between the two tendons. In two cases (1%) the connection was found as an additional tendinous slip of dense regular collagen bundles running from the flexor pollicis longus to flexor digitorum profundus of the index. In one case (1%), there was an aberrant reversed musculotendinous unit running from flexor pollicis longus, and later joined the first lumbrical. This study provides a detailed anatomo-histological description of the interconnection between flexor pollicis longus and flexor digitorum profundus to the index finger. Its etiology could either be congenital or secondarily acquired. Surgeons should be aware of this connection for better diagnosis, surgical planning and treatment of diseased hands.

Duplication of the inferior vena cava was detected in a 71-year-old Thai male cadaver with unknown cause of death. Two inferior vena cavae located on each side of the lumbar vertebrae were identified. The right inferior vena cava was formed by fusion of the right and left common iliac veins and had a normal course, while the left inferior vena cava arose from the left branch of the left external iliac vein and ascended parallel to the abdominal aorta. To our knowledge, no similar case has been previously reported. The left inferior vena cava joined the left renal vein to become the preaortic trunk before joining the right inferior vena cava. Tributaries of the inferior vena cava were observed and followed. Development of the duplication of the inferior vena cava was reviewed. Anatomical and developmental comprehension of the duplication of the inferior vena cava is important for clinicians in planning for retroperitoneal surgery.

A total of 100 cadaveric limbs were dissected to study the anatomy of the forearm and hand extensor musculature. Four types of contributions to the index finger were found for the extensor indicis proprius (EIP), including one new type where the double tendons of the EIP inserts volar and radial to the extensor digitorum communis of the index finger (EDC-I). Four variant muscles were identified including the extensor medii proprius (EMP) (in five cadavers), extensor digitorum brevis manus (EDBM) (in one cadaver), extensor indicis et medii communis (EIMC) (in four cadavers) and extensor pollicis et indicis (EPI) (in four cadavers). The absence of the EIP in four cases was substituted by either the EIMC or the EPI. Two unpreviously published cases were found. In one hand, the variant EIMC was present along with the EPI. In another hand, both the EMP and the EDBM were present, and the EMP tendon inserted to the tendon of the EDBM. Awareness of the variations on the dorsum of the hand is essential for diagnosis, surgical planning and treatment of diseased hands.