Teaching and Learning Neuroanatomy with Gestures: A Description of Two Simple Hand Models.

Neuroanatomy ranks highly among the most difficult topics to master in medical school. We describe two gesture-based techniques aimed at simplifying the anatomy of two complex intracranial nervous structures: the trigeminal nerve and the cerebral fornix.

Consolidation Carnival: A Case-Based Approach to Reviewing Musculoskeletal Anatomy in an Undergraduate Medical Curriculum.

Introduction: Recent changes in undergraduate medical curricula have resulted in time constraints that are particularly challenging, especially when students must learn large blocks of musculoskeletal anatomy content. Consequently, students have resorted to rote memorization to cope, which counteracts our established collaborative self-directed learning model. Methods: For a 6-week musculoskeletal anatomy course, two structured case-based review sessions are described, each following the completion of two five-hour lab sessions, two on the upper extremities and two on the lower extremities. These largely self-directed review sessions consisted of 6 students rotating through 7 to 8 stations every 10 minutes where clinical cases with follow-up questions were projected on large screens. The students were expected to work collaboratively to solve the cases utilizing the prosected specimens provided and discuss the accompanying answers at the end of each case. Results: Ninety-four per cent of the students who participated in this study agreed that the case-based review sessions provided a helpful overview of musculoskeletal anatomy content. Student performance on the open-ended, case-based musculoskeletal examination questions showed no significant difference in performance on shoulder, hand, hip, thigh, and leg questions. There was, however, a statistically significant decrease in the students' scores on a forearm question in 2021 compared to 2019. Conclusion: This paper describes our integrated, collaborative musculoskeletal course, including case-based review sessions, which was positively received by students as having value in reviewing the musculoskeletal content though it was not found to improve examination performance.

Integration of physiology in a curriculum on human structure: a snapshot of the cardiovascular block.

With the gradual shift from discipline-based to competency-based medical education, the integrated curriculum has become a popular model for connecting basic science and clinical content in undergraduate medical education. Despite its popularity, there are concerns that important physiological concepts are not adequately addressed. We describe the spiral integration of physiology content in the 5-week Cardiovascular block of our Homeostasis course at the Zucker School of Medicine. We also describe our approach to incorporating physiology into an integrated, constructed response, short-answer assessment format. Our approach to spiral integration consists of rotating lab stations that highlight the distinction between normal and abnormal states, linked with appropriate clinical interventions. Physiology is at the core of integration in any curriculum and the basis of all applied fields of medicine, hence our approach is that teaching structural relationships would not be valuable without consideration of its functions, which can then be utilized in discussion of clinical presentations, imaging, and relevant pathologies. Likewise, our integrated assessments require the students to compose their answers to the questions from scratch, which creates a shift in mode of students' preparation from rote memorizations to more cognitive processing that enhances critical thinking.

A Game-Based Approach to Teaching and Learning Anatomy of the Liver and Portal Venous System.

Introduction: The use of games and game elements as teaching tools has received increasing attention in the medical education literature. Used formatively, games promote student engagement and satisfaction, and encourage collaboration and teamwork among students. They may also help students retain knowledge, although research supporting this notion is limited. This resource contains a 30-minute interactive lab station involving two different game-based activities aimed at teaching functional anatomy of the liver and portal venous system. Methods: The first activity is a flipped version of a traditional pinned anatomy practical, wherein students place their own pins on a body donor in response to application-level prompts. The second activity is an outlay-type card game where students assemble cards to depict the venous drainage of gut organs in a healthy patient versus one with portal hypertension. Results: In end-of-session reviews, several students volunteered feedback that the activities were effective and enjoyable. Additionally, average student scores on two subject exam questions increased by approximately 13% and 4%, compared with students who took the exam before the game elements were introduced. Discussion: These game-based activities may serve as a starting point for others wishing to deal with historically difficult topics in a more engaging way. The tools presented are low-cost, low-tech, and easy to modify for use with different student populations.

Superior mesenteric origin of the proper hepatic artery: embryological and clinical implications.

The hepatic arteries are subject to a great deal of anatomical variation, potentially complicating hepatobiliary surgical procedures as well as general gastrointestinal procedures that involve foregut and midgut structures. We report a case of a rare variant of the proper hepatic artery discovered during dissection of an 84-year-old male cadaver. In this individual, the common hepatic artery was absent and the proper hepatic artery was replaced directly to the superior mesenteric artery. The gastroduodenal artery and the right inferior phrenic artery took origin from the celiac trunk. In addition, there was no identifiable right gastric artery. The celiac trunk gave off three branches: the splenic, left gastric, and gastroduodenal arteries. The entire arterial blood supply to the liver, therefore, was derived from the superior mesenteric artery. Patterns of regression of the ventral branches and the partial disappearance of the ventral anastomotic arteries during embryonic development play a major role in the variations of the gut arteries. An intraoperative encounter with this particular variant carries a significant risk of iatrogenic injury with potentially devastating ischemia and necrotic results. Accurate depiction and definition of the hepatic arterial anatomy are crucial. Variations like the one described here underscore the importance of pre-operative imaging and knowledge of the embryological origins of variation.

Histological comparison of the candidate arteries for bypass grafting of the posterior interventricular artery.

This study evaluated five vessels as potential candidates for coronary artery bypass grafting at the posterior interventricular artery (PIVA) blockage site. We used light microscopy and digital image analysis of H&E and Van Gieson's-stained slides to investigate luminal diameter, arterial wall thickness, and relative muscularity and elasticity of candidate vessels. Results from our sample indicate that the inferior epigastric artery (IEA) may be the preferred graft to the PIVA based on overall similarities in these measurements. Other arteries provided a favorable match based on a single measurement, but the IEA agreed most consistently with the PIVA. When choosing a vessel to bypass blockage at the PIVA, cardiothoracic surgeons should be aware of the many favorable features of the IEA.

And then there were four: Anatomical observations on the pollical palmar interosseous muscle in humans.

Although anatomists generally agree upon the presence of four interosseous muscles in the human hand, the number and identity of the palmar interosseous muscles remains contentious. Recent studies suggest that a majority of human hands possess four palmar interossei, yet most contemporary texts suggest the presence of only three. The pollical palmar interosseous muscle (PPIM), associated with the first digit, has been alternatively interpreted as a distinct muscle, part of another hand muscle, or nonexistent. We examined 45 hands from 23 human cadavers to investigate the prevalence of this muscle and found it to occur in varying degrees of expression in 91% of specimens. We also tested the hypothesis that the PPIM forms the smaller part of a "parallel muscle combination" and is therefore ideally suited to act as a proprioceptive organ. Results do not show a significantly higher density of muscle spindles in the PPIM relative to the adjacent adductor pollicis, provisionally refuting this hypothesis. The presence of the PPIM, observed in the majority of hands from several populations, indicates that it should be regularly included in mainstream anatomy texts and atlases.

The role of the elastic fiber system in the pathogenesis of osteoarthritis and knee joint laxity.

Osteoarthritis (OA) is a disease of synovial joints in which all articular structures are affected. Evidence suggests that a decreased density in the elastic fiber concentration of the knee capsule is associated with joint hypermobility, a condition associated with OA. However, there is no study that shows a direct relationship between the elastic fiber system and knee OA. The purpose of this study is to determine if there is a correlation between the elastic fiber density in medial (MCL) and lateral (LCL) collateral ligaments and the severity of OA. The elastic fiber concentration in MCL and LCL were examined in cadaver knees (n = 10; 4 M, 6 F). The elastic fiber density, measured as the concentration of elastic fibers per unit area, was correlated with the severity of OA, which was graded on a 0-16 scale using histologic and macroscopic markers. Among all subjects, elastic fiber concentrations between MCL (mean 15.49% ± 2.49) and LCL (mean 13.93 ± 3.63) showed a significant difference (P = 0.023). There were no inter-gender differences between the elastic fiber concentration in either MCL or LCL. Among all subjects, the severity of OA was found to be correlated negatively with the elastic fiber concentration in both MCL (r = -0.693, P ≤ 0.05) and LCL (r = -0.718, P ≤ 0.05). This is the first study to show a correlation between the elastic fiber system and knee OA.

Divided and reunited maxillary artery: developmental and clinical considerations.

We describe an anatomical variation of the right maxillary artery, discovered during dissection of a male human cadaver. The right maxillary artery bifurcates into unequal superficial (larger) and deep (smaller) divisions. Each division gives off several branches that distribute to the muscles of mastication, facial structures, and teeth. The superficial and deep divisions then reunite to form a complete loop, before giving off terminal branches in the pterygopalatine fossa. The entire arterial loop lies superficial to the branches of the mandibular nerve. This case provides further evidence for a network of vascular rings that surround soft tissue structures in the developing infratemporal fossa. Persistence of all or part of these rings determines adult anatomy. Extreme anatomical variations such as this one may complicate major procedures such as radical maxillectomy, as well as simple procedures such as inferior alveolar nerve blocks.

Arterio-arterial malformation between a high origin radial artery and brachial artery within the cubital fossa - its clinical and embryological significance: a case report.

INTRODUCTION: Arterial variations of the upper extremity are commonly seen in the radial and ulnar arteries. Arterial variations can be damaged through iatrogenic means if not properly documented. CASE PRESENTATION: A rare arterial anomaly was found in a 61-year-old female cadaver consisting of an arterio-arterial malformation between a high-origin radial artery and the brachial artery within the cubital fossa. The high-origin radial artery arose from the axillary artery, deep to the pectoralis minor muscle. It coursed superficially through the anterior compartment of the arm, converging with the more deeply placed brachial artery in the cubital fossa. CONCLUSION: Our finding demonstrates the still vast array of possible arterial varieties and the need for awareness in order to prevent iatrogenic injury. We also provide supportive evidence of intussusceptive angiogenesis' involvement in the formation of larger vessels.

Objective and subjective assessment of reciprocal peer teaching in medical gross anatomy laboratory.

Reciprocal peer teaching (RPT), wherein students alternate roles as teacher and learner, has been applied in several educational arenas with varying success. Here, we describe the implementation of a reciprocal peer teaching protocol in a human gross anatomy laboratory curriculum. We compared the outcomes of the RPT class with those of previous classes in which RPT was not employed. Objective data (i.e., course grades) show no significant differences in gross anatomy laboratory grades between students in the RPT and non-RPT classes. To subjectively evaluate the relative success of RPT in the laboratory, we analyzed student opinions obtained through anonymous surveys. These data show that a powerful majority of student respondents felt that RPT was beneficial and should be used in future classes. The greatest disadvantage was unreliable quality of teaching from peers; however, most students still felt that RPT should be continued. Students who felt that they had insufficient hands-on experience (by virtue of dissecting only half the time) were significantly more likely to recommend abandoning RPT. These results underscore the importance of active student dissection, and suggest that a modified version of the described RPT protocol may satisfy more of the needs of large, diverse student populations. Several hidden benefits of RPT exist for faculty, administration, and students, including reduced need for large numbers of cadavers, attendant reduction in operating costs, and smaller student-to-teacher ratios.

Bigger than a breadbox; lighter than a heavy heart.

Inexact measurements can have devastating effects in sciences where precision is of paramount importance. In contrast, morphological sciences rely heavily on description, comparison, and estimation to make meaningful inferences about the structure of humans and other animals. A review of the 1918 edition of Gray's Anatomy shows that the tendency to approximate was as marked nearly a century ago as it is today. Occasionally, objects of comparison may themselves become obsolete, necessitating changes in descriptive terminology.

An unusual variation of the flexor digitorum accessorius longus muscle--its anatomy and clinical significance.

In this article we describe a variant accessory muscle found in the deep posterior compartment of the leg in a 96 year-old female human cadaver. The flexor digitorum accessorius longus was found bilaterally, originating by two heads from the shafts of the tibia and fibula. The two heads of the muscle were observed to be subequal in size and none of the fleshy fibers of the muscle entered the tarsal tunnel. This stands in contrast with previous descriptions of accessory digital flexors, which are typically asymmetrical or single-headed, and which almost always introduce fleshy fibers into the tarsal tunnel. This variant structure has the potential to entrap the tibial nerve and compress the posterior tibial vessels either proximal to the talocrural joint or within the tarsal tunnel, and may be implicated in clinical scenarios involving imaging, surgery, compartment syndromes, or deep-vein thromboses.

Unusual accessory tendon connecting the hallucal extensors.

During routine dissection of an adult human cadaver, a suite of tendinous anomalies was discovered in the left hallucal region. Whereas the main tendon of the extensor hallucis longus muscle inserted normally, two accessory tendons were found coursing medial and lateral to the main tendon. The most lateral tendon originated from a supernumerary muscle belly and merged with the tendon of extensor hallucis brevis to form a composite tendon. The most medial tendon crossed the metatarsophalangeal joint and joined the composite tendon deep to the tendon of extensor hallucis longus. A terminal tendon, consisting of these three contributions, inserted upon the proximal hallucal phalanx. This variant likely arose due to atypical differentiation of the common extensor muscle mass during development, and is of particular significance to clinicians performing arthroscopy, tendon transfers, and other surgical procedures.

Assessing macroscopic and microscopic indicators of osteoarthritis in the distal interphalangeal joints: a cadaveric study.

Osteoarthritis is manifested both by macroscopically visible lesions and by specific histological indicators. Although traditional views of the disease process invoke physical abrasion of joint surfaces, recent studies indicate that tissue-level changes may precede grossly visible lesions of articular cartilage. This study investigates the association between gross and histological indicators of osteoarthritis at the manual interphalangeal joints, and examines a sequence of events that may lead to the onset of cartilage degeneration. Interphalangeal joints from the hands of nine cadavers were dissected, of which 52 joints were collected and further evaluated. Gross degradation of the proximal articular surface was graded on a scale of 0-3 (with 0 representing normal cartilage with no visible lesions). Osteoarthritic lesions were found in 86% of specimens and showed no preferential occurrence between males and females or right and left hands. Histological analysis indicated that known microscopic indicators of osteoarthritis always occur in Grade 1-3 specimens, but can also be recognized in some macroscopically normal specimens. Many macroscopically normal specimens exhibited chondrocyte clustering (28.6%) and/or tide mark irregularities (57%), indicating that these features are most likely the earliest to develop in the progression of osteoarthritis. It is possible that the initiating etiology is thickening of the subchondral bone, but this was not directly observed. Results indicate significant thinning of the cartilage as macroscopic degradation progresses. Our study supports, with slight modification, a previously proposed cascade of histological changes that may ultimately lead to the physical destruction of articular cartilage.

The contributions of the Bartholin family to the study and practice of clinical anatomy.

Between 1585 and 1738, four members of the celebrated Bartholin family made significant contributions to anatomical science and medicine. Caspar Bartholin (the elder), two of his sons (Thomas and Rasmus), and his grandson (Caspar the younger) all served on the medical faculty of the University of Copenhagen, and helped to gain international acclaim for the institution. Over three generations, the Bartholins challenged traditional ideas about science and the human body, and discovered anatomical structures and phenomena that would prove crucial to the practice of modern medicine.

Comparative anatomy and histology of xenarthran osteoderms.

Reconstruction of soft tissues in fossil vertebrates is an enduring challenge for paleontologists. Because inferences must be based on evidence from hard tissues (typically bones or teeth), even the most complete fossils provide only limited information about certain organ systems. Osteoderms ("dermal armor") are integumentary bones with high fossilization potential that hold information about the anatomy of the skin in many extant and fossil amniotes. Their importance for functional morphology and phylogenetic research has recently been recognized, but studies have focused largely upon reptiles, in which osteoderms are most common. Among mammals, osteoderms occur only in members of the clade Xenarthra, which includes armadillos and their extinct relatives: glyptodonts, pampatheres, and, more distantly, ground sloths. Here, I present new information on the comparative morphology and histology of osteoderms and their associated soft tissues in 11 extant and fossil xenarthrans. Extinct mylodontid sloths possessed simple, isolated ossicles, the presence of which is likely plesiomorphic for Xenarthra. More highly derived osteoderms of glyptodonts, pampatheres, and armadillos feature complex articulations and surface ornamentation. Osteoderms of modern armadillos are physically associated with a variety of soft tissues, including nerve, muscle, gland, and connective tissue. In some cases, similar osteological features may be caused by two or more different tissue types, rendering soft-tissue inferences for fossil osteoderms equivocal. Certain osteological structures, however, are consistently associated with specific soft-tissue complexes and therefore represent a relatively robust foundation upon which to base soft-tissue reconstructions of extinct xenarthrans.

Integration of morphological data sets for phylogenetic analysis of Amniota: the importance of integumentary characters and increased taxonomic sampling.

Several mutually exclusive hypotheses have been advanced to explain the phylogenetic position of turtles among amniotes. Traditional morphology-based analyses place turtles among extinct anapsids (reptiles with a solid skull roof), whereas more recent studies of both morphological and molecular data support an origin of turtles from within Diapsida (reptiles with a doubly fenestrated skull roof). Evaluation of these conflicting hypotheses has been hampered by nonoverlapping taxonomic samples and the exclusion of significant taxa from published analyses. Furthermore, although data from soft tissues and anatomical systems such as the integument may be particularly relevant to this problem, they are often excluded from large-scale analyses of morphological systematics. Here, conflicting hypotheses of turtle relationships are tested by (1) combining published data into a supermatrix of morphological characters to address issues of character conflict and missing data; (2) increasing taxonomic sampling by more than doubling the number of operational taxonomic units to test internal relationships within suprageneric ingroup taxa; and (3) increasing character sampling by approximately 25% by adding new data on the osteology and histology of the integument, an anatomical system that has been historically underrepresented in morphological systematics. The morphological data set assembled here represents the largest yet compiled for Amniota. Reevaluation of character data from prior studies of amniote phylogeny favors the hypothesis that turtles indeed have diapsid affinities. Addition of new ingroup taxa alone leads to a decrease in overall phylogenetic resolution, indicating that existing characters used for amniote phylogeny are insufficient to explain the evolution of more highly nested taxa. Incorporation of new data from the soft and osseous components of the integument, however, helps resolve relationships among both basal and highly nested amniote taxa. Analysis of a data set compiled from published sources and data original to this study supports monophyly of Amniota, Synapsida, Reptilia, Parareptilia, Eureptilia, Eosuchia, Diapsida, Neodiapsida, Sauria, Lepidosauria, and Archosauriformes, as well as several more highly nested divisions within the latter two clades. Turtles are here resolved as the sister taxon to a monophyletic Lepidosauria (squamates + Sphenodon), a novel phylogenetic position that nevertheless is consistent with recent molecular and morphological studies that have hypothesized diapsid affinities for this clade.