The importance of the palatine bone for endoscopic endonasal skull base surgery.

Endoscopic endonasal skull base surgery is increasingly prevalent, with its scope expanding from pathogens in the midline region to those in the paramedian region. Maximizing anterior sphenoidectomy is important for the median approach, and lateralizing the pterygopalatine fossa is crucial for the paramedian approach. Maximizing the surgical corridor in the nasal cavity and minimizing damage to neurovascular structures are vital for establishing a surgical field with minimal bleeding, ensuring safe, precise, and gentle procedures. However, the relationship between the maxillofacial and skull base bones in endoscopic endonasal skull base surgery is difficult to understand because these bones are intricately articulated, making it challenging to visualize each bone's outline. Understanding important bones and their related neurovascular structures is essential for all skull base surgeons to maximize the surgical corridor and minimize iatrogenic injury to neurovascular structures. This study aimed to elucidate the role of the palatine bone from a microsurgical anatomical perspective. Three dry skulls were used to demonstrate the structure of the palatine bone and its relationship with surrounding bones. A formalin-perfused cadaveric head was dissected to show the related neurovascular structures. The arteries and veins of the cadaveric heads were injected with red- and blue-colored silicon. Dissection was performed using a surgical microscope and endoscope. In addition, the utilization of the palatine bone as a landmark to identify neurovascular structures, which aids in creating a wider surgical field with less bleeding, was shown in two representative cases. The palatine bone consists of unique complex structures, including the sphenoidal process, ethmoidal crest, pterygopalatine canal, and sphenopalatine notch, which are closely related to the sphenopalatine artery, maxillary nerve, and its branches. The ethmoidal crest of the palatine bone is a well-known structure that is useful for identifying the sphenopalatine foramen, controlling the sphenopalatine artery and nerve, and safely opening the pterygopalatine fossa. The sphenoidal process of the palatine bone is a valuable landmark for identifying the palatovaginal artery, which is a landmark used to safely and efficiently expose the vidian canal. The sphenoidal process is easily cracked with an osteotome and removed to expose the palatovaginal artery, which runs along the pharyngeal groove, just medial to the vidian canal. By opening the pterygopalatine canal (also known as the greater palatine canal), further lateralization of the periosteum-covered pterygopalatine fossa contents can be achieved. Overall, the sphenoidal process and ethmoidal crest can be used as important landmarks to maximize the surgical corridor and minimize unnecessary injury to neurovascular structures.

Lorenz Fries on the defense of Avicenna, the prince of physicians: Addressed to the medics of Germany (1530).

During the 14th century CE, a pivotal shift took place in the world of medicine as its epicenter transitioned from the Middle East to Europe. The emergence of the European Renaissance sparked skepticism regarding the significance of Avicenna's contributions to the advancement of medicine. This paper explores how the rise of secularization and the Renaissance in Europe marked significant cultural transformations, fostering the spread of literacy. These societal shifts influenced the trajectory of medical thought, and Avicenna's "Canon of Medicine" received both praise and condemnation amidst the evolving intellectual landscape. In this context, Lorenz Fries composed his "Defense of Avicenna," a testament to his profound admiration for Avicenna's legacy. This paper presents an English translation of Fries' 1530 work, and introduces Fries and Avicenna's "Canon," contextualizing Fries' defense within the broader rejection of Arab-language medical texts in the 16th century. It also explores Avicenna's influence on European medicine and anatomy during the Renaissance and highlights the enduring relevance of his contributions to the annals of science. Fries' defense underscores Avicenna's methodological acumen and emphasizes the importance of a robust theoretical foundation in medical practice. Avicenna's integration of Aristotelianism with Platonism highlighted the necessity of a rigorous method informed by theory in medical analysis. Fries' defense remains relevant today, particularly in advocating for systematic medical analysis against subjective approaches. Avicenna's medical philosophy seems nested within a larger, hopeful attempt to resolve the tensions between science or naturalism and religion or spiritualism. The rejection of Avicenna reflects broader conflicts between Aristotelian and Neoplatonic traditions, suggesting a complex interplay of secularization and theological influences in shaping medical thought during the Renaissance.

Novel Muscle in Infraspinous Fossa.

The infraspinatus muscle (IS) makes a minor contribution to lateral rotation of the arm but mainly serves to stabilize the glenohumeral (GH) joint as part of the rotator cuff. Although reports of variations in the rotator cuff muscles have been documented previously, specific discussions of IS variants are lacking. In this report, we present a novel case of an accessory muscle in the infraspinous fossa and its relationship to the IS, which was normally located. We describe the observed physical features of the muscles and their innervation patterns.

The Posterior Auricularis Muscle as Superficial Landmark for the Sigmoid Sinus and Transverse-Sigmoid Sinus Junction: An Anatomical Study.

PURPOSE: Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery. METHODS: The PAM was dissected in 10 adult cadaveric heads, and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured. RESULTS: The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ, and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus. CONCLUSION: Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neuro-vascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.

The anterior communicating artery variants: a meta-analysis with a proposed classification system.

Morphological and morphometric variants of the anterior communicating artery (AComA) have been described by multiple studies; however, a complete classification system of all possible morphological variants with their prevalence is lacking. The current systematic review with meta-analysis combines data from different databases, concerning the AComA morphological and morphometric variants (length and diameter). Emphasis was given to the related clinical implications to highlight the clinical value of their knowledge. The typical AComA morphology occurs with a pooled prevalence (PP) of 67.3%, while the PP of atypical AComA is 32.7%. The identified AComA morphological variants (artery's hypoplasia, absence, duplication, triplication, differed shape, fenestration, and the persistence of a median artery of the corpus callosum- MACC) were classified in order of frequency. The commonest presented variants were the AComA hypoplasia (8%) and the anterior cerebral artery (ACA) fusion (5.9%), and the rarest ones were the MACC persistence (2.3%), and the AComA triplication (0.7%). The knowledge of those variants is essential, especially for neurosurgeons operating in the area. Given the high prevalence of AComA aneurysms, an adequate and complete classification of those variants is of utmost importance.

Complete transverse basilar cleft associated with hemifacial microsomia.

Transverse basilar cleft (TBC) is an extremely rare variation of the clivus or the basilar part of the occipital bone. In this report, a unilateral transverse basilar fissure was found at the clivus in a head computed tomography of an 18-year-old female patient diagnosed with hemifacial microsomia (HFM). Image analysis of this patient showed shortening of the ramus of the right mandible along with medial displacement of the right temporomandibular joint and hypoplastic right maxilla. In addition, observation of the clivus showed a cleft between the basioticum and basioccipital bones at the level of the pharyngeal tubercle on the right side. This cleft was identified as TBC. Clival variations, TBC included, attributed to HFM have never been reported. This report draws attention to the complex relationship between abnormal development of clivus and HFM syndrome, and sheds light on a possible genetic and molecular association between these two conditions.

Examining Atherosclerosis Patterns in the Circle of Willis: A Case Study of Duplicated Anterior Communicating Artery.

The anterior communicating artery (ACoA) plays a pivotal role in maintaining cerebral hemodynamics, as its diameter is a major determinant of blood collateralization through the circle of Willis following internal carotid artery occlusion. While variations of this artery are not uncommon, data on their clinicopathologic relevance are limited. In this report, we present our observation from a fresh cadaver of a male individual who had succumbed to cardiac causes. The circle of Willis displayed a duplicated ACoA with atherosclerosis that predominantly affected the posterior horn while sparing the anterior horn. The anterior horn was characterized by its shorter length and larger diameter compared to the posterior horn. The paper focuses on elucidating the microsurgical anatomy of this particular ACoA variant and exploring potential mechanisms that may underlie the pattern of atherosclerotic distribution within the circle of Willis. Based on this report, while further evidence is needed for confirmation, it is plausible that the existence of a duplicated ACoA may offer a protective mechanism, ensuring uninterrupted collateral circulation in the event of a blockage in one of the horns. Further analysis of the ACoA and its pattern of involvement in intracranial atherosclerosis is warranted, as the atherosclerotic patterns in this region hold clinical and pathological significance.

Middle meningeal artery arising from the petrous internal carotid artery: Outcome of unusual stapedial artery regression.

Background: The internal and external carotid arterial systems are generally separate regarding branching patterns. However, these two systems do form collateral circulations with their terminal parts. On rare occasions, branches that belong to one arterial system may arise from the other. Case Description: We present a rare variant of a middle meningeal artery, generally derived from the external carotid artery, arising from the internal carotid artery and entering the floor of the middle cranial fossa by traveling through a small unnamed foramen. This anatomy and embryology and other variants of the middle meningeal and petrous carotid systems are discussed. Conclusion: Embryologically, this variant anatomy signifies an atypical regression of the distal stapedial artery and its connection to the external carotid artery. Surgeons who operate on the skull base, vascular interventionalists, and radiologists should be aware of this potential anatomical variation of the skull base.

Angulation of the dural venous sinuses of the posterior cranial fossa: Anatomical study with clinical and surgical applications.

Cerebral vein and dural venous sinus thromboses (CVST) account for 0.5%-1% of all strokes. Some structural factors associated with a potentially higher risk for developing CVST have been described. However, angulation of the dural venous sinuses (DVS) has yet to be studied as a structural factor. The current study was performed because this variable could be related to alterations in venous flow, thus predisposing to a greater risk of CVST development. Additionally, such information could help shed light on venous sinus stenosis (VSS) at or near the transverse-sigmoid junction. The angulations formed in the different segments of the grooves of the transverse (TS), sigmoid (SS), and superior sagittal sinuses (SSS) were measured in 52 skulls (104 sides). The overall angulation of the TS groove was measured using two reference points. Other variables were examined, such as the communication pattern at the sinuses' confluence and the sinus grooves' lengths and widths. The patterns of communication between sides were compared statistically. The most typical communication pattern at the sinuses' confluence was a right-dominant TS groove (82.98%). The mean angulations of the entire left TS groove at two different points (A and B) were 46° and 43°. Those of the right TS groove were 44° and 45°. The median angulations of the left and right SSS-transverse sinus junction grooves were 127° and 124°. The mean angulations of the left and right TS-SSJsv grooves were 111° (range 82°-152°) and 103° (range 79°-130°). Differentiating normal and abnormal angulations of the DVSs of the posterior cranial fossa can help to explain why some patients are more susceptible to pathologies affecting the DVSs, such as CVST and VSS. Future application of these findings to patients with such pathologies is now necessary to extrapolate our results.

A histology guide for performing human cadaveric studies: SQIP 2024 what to look for with light microscopy.

Histological observation under light microscopy has long been used in human cadaveric studies. However, it can distort the interpretations of findings if not used appropriately; there is no guide for its proper use. The aim of this article is to revisit and discuss the correct use of histology in human cadaveric studies, following discussions with experts in multiple fields of medicine, and to create the first guide for such usage. We reached a consensus with the experts, agreeing that when this principle (structure, quantification, interaction, position: SQIP) is applied to histological observations, the findings will be interpreted correctly. Appropriate use of this recommendation can make human cadaveric studies more accurate and informative. This is the first histology guide for human cadaveric studies.

Renal vein valves: a prevalence, microanatomical and histological study.

PURPOSE: In the modern era of robotic renal procedures and diagnostics, an even more detailed anatomical understanding than hitherto is necessary. Valves of the renal veins (RVV) have been underemphasized and have been disputed by some authors, and few textbooks describe them. The current anatomical study was performed to address such shortcomings in the literature. METHODS: One hundred renal veins were studied in fifty adult formalin-fixed cadavers. Renal veins were removed from the abdomen after sectioning them flush with their entrance to the renal hilum. The inferior vena cava was then incised longitudinally and opened, and RVV were examined grossly and histologically. A classification scheme was developed and applied to our findings. RESULTS: Nineteen RVVs were observed in the fifty cadavers (38%). Four (8%) valves were found on right sides and fifteen (30%) on left sides. The valves were seen as cord/band-like, folds, and single and double leaflets. Histologically, they were all extensions of the tunica intima. CONCLUSION: On the basis of our study, RVV are not uncommon. They were more common on left sides, and on both sides, they were found within approximately one centimeter of the junction of the inferior vena cava and renal vein. Although the function of such valves cannot be inferred from this anatomical study, the structures of the Single leaflet valve (TS2) and Double leaflet valve (TS3) valves suggest they could prevent venous reflux from the IVC into the kidney.

Personalized strategies for academic success in learning anatomy: Exploring metacognitive and technological adaptation in medical students.

Personalization of learning is an educational strategy rooted in metacognition and is significant in academic training. This is especially true in medical contexts. This study explored the relationship between the metacognitive profile of students of human anatomy, the classification of questions according to their difficulty, and the anatomical domain. It also covered the integration of educational technologies to create personalized learning environments. The identification of metacognitive profiles ("Active", "Pragmatic", "Theoretical", and "Reflective") has been highlighted as a critical influence on students' responses to different pedagogical approaches. Personalized adaptation based on these profiles has shown potential for improving grades and increasing student satisfaction and engagement with learning. The results revealed variations in student performance in relation to different pedagogical approaches, learning units, and evaluation modalities. The "Experience" evaluation modality, personalized according to metacognitive profiles, level of competence, and learning objectives, resulted in higher average scores. However, there was significant variability in the results. Those findings confirm the effectiveness of metacognitive adaptation in improving academic performance. Furthermore, they provide a solid basis for formulating personalized and effective pedagogical strategies in medical education. They recognize the influence of metacognitive profiles on student performance and contribute to advancing medical pedagogy.

Evolution of the term "epicondyle of the femur": Revisiting the anatomical and surgical literature.

The femoral epicondyle is an anatomical bony landmark essential for surgeons and anatomists, but there are discrepancies between the two fields when using this term. In current orthopedic surgery, it commonly denotes the small bony prominence of the femoral condyle. Given the derivation, "epicondyle" should be a region projecting laterally from the articular surface rather than a point. These discrepancies in usage are found not only between the fields but also in the literature. This article reviews the narrative definition of "epicondyle of the femur" in surgery and the evolution of the term in anatomy. The outcomes of the review suggest a relationship between the differing perceptions of the epicondyle and the evolution of the term. In reports of studies related to the epicondyle, it is strongly recommended that the definition of the word is clearly stated, with an understanding of its evolution.

The Top 100 Most Cited Journal Articles on Hydrocephalus.

Hydrocephalus represents a significant burden of disease, with more than 383,000 new cases annually worldwide. When the magnitude of this condition is considered, a centralized archive of pertinent literature is of great clinical value. From a neurosurgical standpoint, hydrocephalus is one of the most frequently treated conditions in the field. The focus of this study was to identify the top 100 journal articles specific to hydrocephalus using bibliometric analysis. Using the Journal of Citation Report database, 10 journals were identified. The Web of Science Core Collection was then searched using each journal name and the search term "hydrocephalus." The results were ordered by "Times Cited" and searched by the number of citations. The database contained journal articles from 1976 to 2021, and the following variables were collected for analysis: journal, article type, year of publication, and the number of citations. Journal articles were excluded if they had no relation to hydrocephalus, mostly involved basic science research, or included animal studies. Ten journals were identified using the above criteria, and a catalog of the 100 most cited publications in the hydrocephalus literature was created. Articles were arranged from highest to lowest citation number, with further classification by journal, article type, and publication year. Of the 100 articles referenced, 38 were review articles, 24 were original articles, 15 were comparative studies, 11 were clinical trials, six were multi-center studies, three were cross-sectional, and three were case reports with reviews. Articles were also sorted by study type and further stratified by etiology. If the etiology was not specified, studies were instead subcategorized by treatment type. Etiologies such as aqueductal stenosis, tumors, and other obstructive causes of hydrocephalus were classified as obstructive (n=6). Communicating (n=15) included idiopathic, normal pressure hydrocephalus, and other non-obstructive etiologies. The category "other" (n=3) was assigned to studies that included etiologies, populations, and/or treatments that did not fit into the classifications previously outlined. Through our analysis of highly cited journal articles focusing on different etiologies and the surgical or medical management of hydrocephalus, we hope to elucidate important trends. By establishing the 100 most cited hydrocephalus articles, we contribute one source, stratified for efficient referencing, to facilitate clinical care and future research on hydrocephalus.

What is the axillary arch (of Langer)?

We read with great interest the article by Weninger et al. (2023) on the presence of the axillary arch (AA) (of Langer) found during anatomical dissections-"Axillary arch (of Langer): A large-scale dissection and simulation study based on unembalmed cadavers of body donors." The authors performed their study using 400 axillae from 200 unembalmed cadavers; they identified this variant muscle in 27 axillae of 18 cadavers. Weninger et al. (2023) described the muscular AA in 15 cases; AA was composed of connective tissue in six cases, and AA comprised muscular and connective tissue in six cadavers. Moreover, these authors indicated that after passive abduction and lateral rotation of the arm, 17 arches (63%) came into contact with the neurovascular axillary bundle, which is of clinical importance. In our opinion, this is the most precise and detailed AA muscle study in the literature, illustrated with excellent photographs and schemes. Such studies expand the existing data in the literature and are of real help to clinicians. However, we want to present our modest comments about the title of the article and would like to pose the question, "What is the axillary arch (of Langer)?" Weninger et al. (2023) stated that connective or muscular tissue crossing the axilla is termed the AA (of Langer). This structure splits from the latissimus dorsi muscle, crosses the axilla, and joins the anterior part of the upper limb. The first detailed description of this variation was published in 1846 by Karl Langer Ritter von Edenberg (Langer, 1846). Nowadays, a significant number of articles term all muscular and fibromuscular connections between the latissimus dorsi muscle and the anterior part of the upper limb as "Langers AA" (Markou et al., 2023; Sang et al., 2019; Scrimgeour et al., 2020; Taterra et al., 2019). What Langer described in his work "Zur anatomie des musculus latissimus dorsi" was a fibrous thickening of the medial edge of the axillary fascia between the borders of the pectoralis major and the latissimus dorsi muscles, a structure he termed "Achselbogen." In a sequel of this article, Langer investigated muscular fibers inserting at or encircling the connective tissue "Achselbogen" (Langer, 1846). Therefore, in our opinion, in the study of Weninger et al. (2023), the term AA (of Langer) should only be used to describe the cases presenting solely with a connective tissue "arch" or these comprised of both, muscular and connective tissue. Weninger et al. (2023) noted that muscle fibers could not be excluded in these cases. Of course, to answer this question accurately, a histological study of these cases would be necessary.

The enigmatic os supratrochleare anterius: from rarity to recognition in elbow pathology-case report and review of literature.

Accessory bones around the elbow are scarce, with a reported mean incidence rate of 0.77%. The rarest one is the os supratrochleare anterius, with only a handful of documented cases in the literature. Despite their scarcity, various types of ossicles have been documented, posing diagnostic challenges and potential misinterpretation on X-rays. Herein, we report a case of an accidentally found os supratrochleare anterius in a 43-year-old pig farmer presenting with symptoms of tennis elbow. After conservative treatment with nonsteroidal anti-inflammatory drugs and physiotherapy, he made a full recovery within 2 weeks. This report emphasizes the rarity of the ossupra trochleare anterius, the importance of accurate diagnosis, and the need for continued research and awareness of this anatomical variation.

Exploring the variations of the pancreatic ductal system: a systematic review and meta-analysis of observational studies.

The exocrine part of the pancreas has a duct system called the pancreatic ductal system (PDS). Its mechanism of development is complex, and any reorganization during early embryogenesis can give rise to anatomical variants. The aim of this study is to collect, classify, and analyze published evidence on the importance of anatomical variants of the PDS, addressing gaps in our understanding of such variations. The MEDLINE, Web of Science, Embase, and Google Scholar databases were searched to identify publications relevant to this review. R studio with meta-package was used for data extraction, risk of bias estimation, and statistical analysis. A total of 64 studies out of 1,778 proved suitable for this review and metanalysis. The meta-analysis computed the prevalence of normal variants of the PDS (92% of 10,514 subjects). Type 3 variants and "descending" subtypes of the main pancreatic duct (MPD) predominated in the pooled samples. The mean lengths of the MPD and accessory pancreatic duct (APD) were 16.53 cm and 3.36 cm, respectively. The mean diameters of the MPD at the head and the APD were 3.43 mm and 1.69 mm, respectively. The APD was present in only 41% of samples, and the long type predominated. The pancreatic ductal anatomy is highly variable, and the incorrect identification of variants may be challenging for surgeons during ductal anastomosis with gut, failure to which may often cause ductal obstruction or pseudocysts formation.